Relation of Pyloric Motility to Pyloric Opening and Closure in Healthy Subjects

466 Gut, 1992, 33, 466-471

Relation ofpyloric motility to pyloric opening and closure in healthy subjects Gut: first published as 10.1136/gut.33.4.466 on 1 April 1992. Downloaded from

G Tougas, M Anvari, J Dent, S Somers, D Richards, G W Stevenson

Abstract glyceride in association with suppression of The relation between pyloric motor activity, antral pressure waves.'3 The pyloric phasic con- opening, and closure was examined in eight tractions usually occur at a rate ofabout 3/minute healthy men. Manometry was performed with and have been named isolated pyloric pressure an assembly combining 13 side holes and a waves (IPPWs). Analysis of the mechanical sleeve sensor positioned astride the pylorus. patterns of the triglyceride induced pyloric Simultaneous with manometry, pyloric open- motor response indicates that both the tonic and ing and closure and antroduodenal contrac-_ phasic components should be obstructive to flow tions were observed fluoroscopically with the ofgastric contents into the duodenum. antrum filled with barium. During intra- In this study we have used a recently validated duodenal normal saline infusion, coordinated approach to pyloric manometry to investigate, in antral pressure waves swept over the pylorus humans, the hypothesis that the pylorus has the and ejected barium into the duodenum. No capacity to interrupt gastric emptying. In order localised pyloric motor pattern was observed to do this, we stimulated localised pyloric tonic under these conditions. In contrast, the intra- and phasic contractions with intraduodenal tri- duodenal triglyceride infusion was associated glyceride infusion and observed fluoroscopically with the absence of antral pressure waves and the effect of these contractions on pyloric open- virtual absence ofantral wail movement. At the ing and closure and the movement of barium pylorus, there was a zone of luminal occlusion from the stomach into the duodenum. less than 1 cm long that persisted for the period of observation. This zone of luminal occlusion corresponded precisely with manometric Methods recordings of a narrow zone of pyloric phasic and tonic activity. During the duodenal tri- SUBJECTS

glyceride infusion, the pylorus was closed for Studies were done in 11 healthy male volunteers http://gut.bmj.com/ 98*5% of the measurement period when basal whose mean age was 26 years (range 19-42 pyloric pressure was 4 mm Hg or more, and years). None reported taking any medications or during this motor pattern, barium did not drugs or had a past history ofany gastrointestinal traverse the pylorus. Localised pyloric diseases or smoking. Written informed consent contractions cause sustained pyloric closure, was obtained from each volunteer and the study whether these contractions are phasic or tonic. was approved by the Ethical Committee and

These contractions occur independently of Research Advisory Committee of the McMaster on October 3, 2021 by guest. Protected copyright. antral or duodenal contractions and may inter- University Medical Centre. rupt gastric emptying.

EXPERIMENTAL PROTOCOL Intraduodenal infusion of triglycerides and After a 12 hour overnight fast, a sleeve/side hole fatty acids delays gastric emptying in both manometric assembly (see below) was passed humans and dogs. 2 This effect has been ascribed through a nostril into the stomach. The subject to various demonstrated changes in motor func- then lay on his right side to help the passage ofthe tion - suppression of antral contractions,"5 weighted tip ofthe assembly into the duodenum. reduction in gastric fundal tone,6 and increased The sleeve was then positioned so that it was McMaster University resistance to liquid gastroduodenal outflow.3 The astride the pylorus and the tip of the assembly Medical Centre, exact role of the pylorus in controlling gastric was within the distal duodenum. Proper posi- Hamilton, Ontario, Canada outflow has been controversial for years. There tioning of the assembly was assessed by three G Tougas are conflicting data on patterns ofpyloric motility methods as follows: (1) progression of the distal S Somers during fasting7"'0 and during delivery of acid or end was observed by recognition of the usual D Richards lipids into the duodenum. Some studies in fasting manometric patterns; (2) the location of G W Stevenson humans have shown stimulation of localised the sleeve sensor was determined fluoro- The Royal Adelaide pyloric tonic and phasic contractions while scopically before starting the experimental proto- Hospital, Adelaide, others have shown no such responses.8" 2 col, the sleeve having a metal coil built in along its South Australia, Australia It has recently become evident that the con- length as a stiffener; (3) the exact location of the M Anvari flicting findings on pyloric motor function have sleeve sensor across the pylorus was confirmed J Dent arisen primarily from the use of techniques that and subsequently monitored using continuous Correspondence to: are poorly suited to pyloric manometry. 3 A dual point transmucosal potential difference Dr G Tougas, McMaster hole of University Medical Centre, detailed manometric side analysis measurements (TMPD) (see below). Room 4W8, 1200 Main Street patterns of pyloric motility has shown that the After positioning of the sleeve sensor astride West, Hamilton, Ontario, pylorus contains a zone less than 1 cm in length the pylorus, and after the occurrence of the first Canada, L8N 3Z5 in Accepted for publication which develops tonic and phasic contractions episode of phase III of the interdigestive migrat- 10 June 1991 response to intraduodenal infusions of tri- ing motor complex, normal saline solution was Relation ofpyloric motility to pyloric opening and closure in healthy subjects 467

infused at 1 ml/minute (four subjects) or 3 ml/ distal duodenal side hole was used also to infuse minute (four subjects) into the duodenum for five the saline or triglyceride emulsion into the duo- minutes. The infusate entered the duodenum 5 denum. A tungsten weight was incorporated into cm distal to the aborad margin of the sleeve the distal end of the assembly to aid its passage sensor via a channel incorporated into the mano- from the stomach into the duodenum. metric assembly. A 50 to 100 ml bolus of a The side holes and sleeve sensor were perfused Gut: first published as 10.1136/gut.33.4.466 on 1 April 1992. Downloaded from diluted barium sulphate suspension was then by two low compliance pneumohydraulic per- swallowed, the transpyloric flow of which was fusion systems (Arndorfer Medical Specialties, observed fluoroscopically for the subsequent Greendale, Wisconsin, USA, and Mui Scientific, three minutes with the subject lying on his right Mississauga, Ontario, Canada). The reservoirs of side in the position that displayed the pylorus both pumps were set at a pressure of 15 psi giving best (see below). a flow of0 6 ml/min to each manometric channel. After a 10 minute recovery period, and with Degassed distilled water was used in all channels the subject still lying on his right side, a tri- except the two side holes at the orad and aborad glyceride emulsion (Intralipid 10%) was infused sleeve margins. These were perfused with into the duodenum, again at rates of 1 to 3 ml/ normal saline from separate reservoirs so minute (four subjects at each rate) for five measurements of TMPD could be made concur- minutes. The volunteer then took a further 100 rently with manometry. cc of barium and the distal antral and pyloric Pressures were detected with external trans- outlines were examined fluoroscopically for three ducers - either model 4-327-1 (Bell and Howell minutes, during which manometric recordings Ltd, Pasadena, California, USA) or model were made and the triglyceride infusion main- 12N4696 (Cobe Ltd, Lakewood, Colorado, tained at the same rate. USA) - on two eight channel polygraphs, these The Intralipid 10% (Kabivitrum, Dorval, being a Grass model 17D (Quincy, Massa- Canada) is a fractionated soya bean emulsion in chussetts, USA) and a Sensormedics Dynograph water with 10 g of soya bean oil, 1-2 g of egg 611 (Schiller Park, Illinois, USA). phospholipid, 2-25 g of glycerine/100 ml. Its osmolarity is 280 mOsm/l, and its caloric content is 1100 kcal/l (4620 kJ/l). Its major fatty acids are TRANSMUCOSAL POTENTIAL DIFFERENCE linoleic acid and oleic acid. MEASUREMENTS Transmucosal potential difference was detected from the saline perfused side holes at both ends of MANOMETRIC TECHNIQUE the sleeve using previously described methods. '3 The methods of antropyloroduodenal mano- The saline perfusate transmitted the potential up metry used in this study have been described in the manometric assembly into the transducer detail previously.'4 A 14 lumen manometric dome from which a bridge containing 1 mol/l http://gut.bmj.com/ sleeve assembly was built specifically for these potassium chloride in 3% agar transferred the experiments. The 4 5 cm long sleeve was used to signal to a calomel half cell (Ionode, Brisbane, monitor pyloric pressures.'5 The arrangement of Australia). A saline filled subcutaneous electrode side holes is shown in Figure 1. The side holes inserted into the forearm served as a reference located at the upper margin of the sleeve, and at electrode. The potentials were detected with a 2 5 and 5 cm orad to this level, monitored antral dual channel purpose built system which gave a pressures. The side holes arrayed at 5 mm continuous output to the Grass recorder (Multi- on October 3, 2021 by guest. Protected copyright. intervals within the sleeve length allowed assess- channel p/pH system 1201, BME, Flinders ment of the spatial patterns of pressure waves Medical Centre, Bedford Park, South Australia, across the pylorus. Duodenal pressures were Australia). monitored from the three side holes 0, 2 5, and 5 The position of the sleeve was adjusted so that cm aborad from the distal sleeve end. The most the following criteria for position were satisfied: (1) duodenal side hole TMPD equal to or more negative than -15 mV; (2) gastric side hole TMPD equal to or more positive than -20 mV; and (3) a gradient between the two TMPD side holes of greater than 15 mV.

RADIOLOGY Fluoroscopy was done on a remote control table. Before manometric recordings were started, the optimal position for radiological evaluation ofthe L - Sleeve sensor pylorus was determined by giving the subject a small volume of barium sulphate. The subject was then positioned so that a right angled view of the pyloric canal was obtained, to permit evaluation of pyloric canal diameter and determine Figure 1: Schematic representation ofthe whether the pylorus was open or closed. This manometric assembly with usually required a prone oblique position, the sleeve sensor positioned occasionally supine oblique, both with the right across the pylorus. The inset shows the position ofthe 9 side down, and with variable table tilt of up to side holes that spanned the 500. This position was maintained thereafter. A length ofthe sleeve sensor. small field of view was used, approximately 6 x 6 468 Tougas, Anvari, Dent, Somers, Richards, Stevenson

cm, and gonads as well as the neck were shielded Radiology in all studies. The state of the pyloric lumen was defined as The radiation dosage was calculated using a open, closed, or indeterminate for each of the 15 6 x 6 skin entry exposure, with the patient second periods in which mean basal pyloric

oblique, so that the patient's spinal cord was not pressure was measured. Ifthe lumen was open at Gut: first published as 10.1136/gut.33.4.466 on 1 April 1992. Downloaded from in the primary beam. Using these parameters, any time during the 15 seconds, the period was the estimated radiation dose was 22-25 mrad defined as open. In general it was possible to (22-25 x 10-5 Gy). determine precisely the moment that the pylorus The fluoroscopy was recorded on a 3/4 inch opened and closed. The state of the pylorus was video cassette recorder (Sony) with simultaneous indeterminate only when the pyloric canal was recording of a superimposed image of the sleeve obscured by barium containing overlapping manometric tracing processed through a signal loops ofdistal duodenum or proximal duodenum mixer (Hewlett-Packard). This allowed for exact or jejunum, despite best attempts at achievement temporal correlation ofthe radiological data with of optimal positioning of the x ray tube and the pyloric manometric recordings. subject. Statistical analysis ANALYSIS OF DATA A 2 x 2 table was constructed for correlation of pyloric opening or closure versus pyloric pressure Manometry (relative to antral pressure) and one way analysis Records were only analysed when the TMPD of variance (Anova) was used for statistical readings satisfied the criteria for correct sleeve analysis of the relation between pyloric tone and position as given above. opening of the pyloric lumen. Pressure waves were defined as increases in The paired Student's t test was used for intraluminal pressure equal to or greater than 10 statistical validation of the response to intra- mm Hg which lasted less than 20 seconds. duodenal lipid infusion compared with saline When the sleeve recording indicated a pressure infusion. wave which occurred in the absence of any discernible deflection of antral or duodenal pressure as recorded by the side holes at or beyond Results the margins of the sleeve, an isolated pyloric Studies were performed in 11 subjects, but pressure wave (IPPW) was scored. When there incomrplete data were obtained in three early on was an antral or duodenal pressure wave that had in the project because the introduction of the occurred within 2 seconds of the onset of the barium into the stomach resulted in displace-

IPPW recorded by the sleeve, an antropyloric or ment of the sleeve into the antrum which could http://gut.bmj.com/ antropyloroduodenal wave was scored. not be rectified by attempts at repositioning. When an IPPW was scored, its longitudinal Subsequently, this aborad movement of the extent and position on the sleeve was defined by pylorus was allowed for by passing the sleeve examination ofthe tracings from the array ofside distally into the duodenum before giving barium. holes at 5 mm intervals along the sleeve length The data presented below are derived solely from (Fig 1). the eight subjects in whom technically satisfac-

Basal pyloric pressure obtained with the sleeve tory recordings were obtained under the two on October 3, 2021 by guest. Protected copyright. sensor was referenced to basal antral pressure. study conditions. For the purposes of analysis of basal pyloric The patterns of motility associated with intra- pressure, IPPWs were edited by drawing a duodenal triglyceride infusion were as described straight line from the onset of their major up- previously,'4 being pyloric tone, IPPWs, and stroke to the end of their major downstroke. suppression of antral and duodenal contractions Mean basal pyloric pressure was expressed as the (Fig 2). By contrast, the dominant motor pattern mean values for each 15 second period. associated with intraduodenal saline infusion was Manometric responses

80 At 80 40 40 Antrum 0 01- 80 ~~~~~~Antrum 80T :1 4 Antru m Figure 2: Manometric tracings showing the patterns ofantropyloroduodenal {0 Pylorus 801you motility during duodenal saline and triglyceride infusions. With saline infusion, antral pressure waves are propagated into 80 30 s 80 T the pylorus whereas during triglyceride infusion, pyloric 40T --Duodenum 40+ 30s Duodenum tonic activity and isolated o- pyloric pressure waves are o- present and antral activity is absent. lntraduodenal saline Intraduodenal triglyceride Relation ofpyloric motility to pyloric opening and closure in healthy subjects 469

TABLE I Pyloric manometnc patterns during normal saline being no evidence of peristaltic pumping of or triglyceride duodenal infusion barium by this type of contraction. Duodenal infusate Antropyloroduodenal waves occurred in the setting of absent pyloric tone in 7 of the 8 Saline Tiglycerid: p subjects. These waves occluded the lumen of the Gut: first published as 10.1136/gut.33.4.466 on 1 April 1992. Downloaded from Pyloric pressure (mm distal antrum as they advanced towards the Hg) 0-33 (2 04) 6-56 (3-63) <0-0001 IPPWs (no/min) 0-97 (0 39) 2-63 (0 73) <0-002 already open pylorus. Pumping of barium was observed in advance of the lumen occluding IPPW=isolated pyloric pressure waves. contraction. The pylorus took part in the pro- Values, mean (SD). gression of the wave into the duodenum as the TABLE II Relation between pyloric aperture and pyloric pressure wave and radiological zone of lumen pressure occlusion were seen to traverse the side holes arrayed along the sleeve length. The six Pyloric lumen antropyloroduodenal waves that occurred in the Pyloric pressure Closed Open subject in whom pyloric tone was present in >2 mm Hg 1 (1-6%) 63 (98 4%) association with saline infusion also propelled 62 mm Hg 72 (97 4%) 2 (2 6%) barium across the pylorus. The radiological outlines of the antropyloro- The number is the total of 15 second periods evaluated. duodenal segment were distinctly different during the two study conditions. In association irregular occurrence of antropyloroduodenal with triglyceride infusion, the antrum was globu- pressure waves, and absence of pyloric tone and lar and because there was no emptying ofbarium IPPWs (Fig 2). Data on the patterns of pyloric into the duodenum, it was not necessary to refill motility that occurred during the period of the antrum with barium as recordings were fluoroscopic observation in the eight subjects are made. There was a deep, static, lumen occluding given in Table I. ring at the pylorus when pyloric tone and IPPWs Table II summarises the relation of sleeve were present. This ring was approximately 1 cm recorded basal pyloric pressure to the presence of long as judged by comparison with the length of a barium column across the pylorus for the two the spring wire which stiffened the sleeve (Fig 3). conditions studied. In 98-4% of the 15 second This ring was always seen to be astride the sleeve periods during which basal pressure was greater length when the TMPD recordings satisfied than 2 mm Hg, the pylorus was closed around the criteria for correct positioning (see methods). sleeve assembly. A barium column extended The appearance ofthe ring did not change during across the pylorus in 97-4% of periods in which IPPWs, indicating that tonic and phasic contrac- http://gut.bmj.com/ basal pyloric pressure was less than or equal to 2 tions occurred in an identical zone. The length of mm Hg. Pyloric pressure was present intermit- the pyloric lumen that was observed to be tently in two subjects; pyloric closure and open- consistently occluded correlated well with manometry, as 89% (61/65) of all IPPWs recorded Figure 3: Fluoroscopic ing were consistently related to the presence or appearance ofthe absence of pyloric pressure greater than 2 mm during fluoroscopy were seen in only one side antropyloroduodenal Hg. hole indicating that the zone of localised pyloric segment during duodenal All IPPWs occurred when pyloric tone was contraction was usually equal to or less than 1 cm triglyceride infusion. The in length. In keeping with the radiological on October 3, 2021 by guest. Protected copyright. pylorus is closed and no present. Consequently, the pylorus was always barium is noted across the closed just before the onset of each IPPW. The appearances, pyloric tone was recorded from the static, ring like occluded presence of tone made it impossible to examine same side holes as IPPWs. The position of the segment. As can be seen by the manometric tracingfrom the impact ofIPPWs alone on patterns of pyloric side hole that recorded pyloric tone and IPPWs the sleeve on the bottom opening and closure. Throughout every IPPW, was in accord with the position of the lumen right, isolated pyloric however, pyloric closure was maintained, there occluding ring on the pylorus, as judged fluoro- pressure waves are present in scopically by reference to the sleeve spring wire the pyloric segment. stiffener. In two subjects there was no discernible inden- tation of the antrum that was either temporally linked or independent ofIPPWs. In the other six subjects, a detectable ripple ofthe antral contour which propagated aborally, but died out before it reached the terminal antrum was seen. The antral ripple was not accompanied by any increase in antral pressure nor was it clearly coordinated with IPPWs (Fig 4). In association with intraduodenal saline infusion, the antrum emptied rapidly and so required refilling with barium during the period offluoroscopy. No discrete pyloric ring could be discerned (Fig 5).

Discussion These studies are the first performed in humans in which it has been possible to examine system- atically the effect of pyloric tone and IPPWs on transpyloric flow. The observations illustrate 470 Tougas, Anvari, Dent, Somers, Richards, Stevenson

opening and closure in humans. We used fluoroscopy, since this is the only technique that gives adequate resolution of the luminal contours on a second by second basis. The manometric technique used has been developed specifically for Gut: first published as 10.1136/gut.33.4.466 on 1 April 1992. Downloaded from pyloric manometry and has been validated recently by us.'3 Our data in this study indicate clearly that a basal pyloric pressure more than 2 mm Hg above distal antral pressure occludes the human pyloric lumen and consequently prevents transpyloric flow, since the associated suppression of antral contractions means that there are no antral forces that can overcome this weak luminal occlusion. Our observations in this study now define the functional significance of pyloric motor responses that we have recorded mano- metrically in previous human studies.'3 Studies of the pyloric diameter in conscious dogs by Ehrlein have produced results consistent with those reported in the present study.'7 Ehrlein used the extraluminal inductograph method originally developed by Brody and Figure 4: Antral 'ripple' of Quigley.'8 Duodenal instillation of hydrochloric typical amplitude seen during duodenal triglyceride how profoundly intraduodenal stimuli can alter acid or oleic acid resulted in a diminution of the infusion which was causing both antropyloroduodenal motility and the pyloric diameter to a level consistent with isolated pyloric pressure movement of luminal contents. Our major find- luminal closure, a change that was associated waves (IPPWs) and pyloric tone. As seen in the motility' ing is that intraduodenal triglyceride infusion with the cessation of gastric emptying.' This tracing, the ripple was not induces a pyloric contraction pattern which supports the view that pyloric closure plays a role related in time to an IPPW causes sustained closure of the pylorus and in preventing transpyloric flow. The methods and did not produce any antral luminal pressure cessation ofgastric emptying. used by Ehrlein would not have allowed him to increase. The IPPWs that It could be argued on the basis of simple recognise phasic pyloric contractions if the occurred during the same mechanics and studies in other sphincteric pylorus were already closed. Thus, the tracings period were not phase locked regions, that it is unnecessary to show that the obtained by Ehrlein in his study are consistent with these antral ripples. with our own data. presence of a sustained pressure barrier at the http://gut.bmj.com/ pylorus would be associated with pyloric luminal What is the mechanical importance ofIPPWs? The present study suggests that they are rela- Figure 5: Fluoroscopic closure and cessation of transpyloric flow. There appearance ofthe pylorus has been much controversy about the mechanical tively unimportant as controllers of transpyloric during intraduodenal saline roles of the pylorus and the motor patterns it flow, given that pyloric tone was always present infusion. The pylorus is displays."'0 6 There has also been scepticism when IPPWs occurred and that pyloric tone wide open and barium is alone closed the In our seen within the lumen. No about whether manometry is a reliable method pylorus. previous studies, however, we have often recorded stimulation of pyloric tone or isolated for recording pyloric motility.'" We therefore on October 3, 2021 by guest. Protected copyright. pyloric pressure waves were considered it important to study directly the IPPWs in the absence of pyloric tone'4 and we occurring, the oscillations of expected that this would be the case in the the manometer were caused relation of patterns of pyloric pressure to pyloric by respiration present study. Our fluoroscopic and manometric data indicate that IPPWs are non-propagated contractions localised to the zone of tonically contracted pylorus. The use of multiple manometric sampling points and simultaneous fluoroscopy shows clearly that IPPWs are distinct from the terminal antral contractions observed in humans by Smith et al. '9 We propose that transpyloric flow would also be obstructed during IPPWs that occur in the absence of pyloric tone, the effect of this being to 'chop' any transpyloric flow that might be occurring between IPPWs. Such an effect could produce a more graded braking of gastric emptying by the pylorus than could be produced by a pyloric tonic response. It is possible that IPPW responses occur without the development ofpyloric tone at lower levels of stimulation of duodenal receptors by nutrients. , The high rate of intraduodenal lipid infusion used in the present study may explain why we saw pyloric tone so consistently, since triglyceride was delivered to the duodenum at a rate twice that used in a previous study in which we recorded stimulation of IPPWs without tone in about half of the subjects. Furthermore, after food we have recorded intermittent occurrence of IPPWs alone. Tougas, Anvari, Dent, Somers, Richards, Stevenson 471

The radiological appearances during saline JD was supported by the Canadian Medical Research Council and a grant from Astra Pharmaceuticals, Sydney, Australia. and triglyceride infusions were markedly differ- This work was presented in part at the Meeting of the American ent, but consistent with the manometric data. Gastroenterological Association in May 1988. Many would consider that the appearances

1 Keinke 0, Ehrlein H-J. Effect of oleic acid on canine Gut: first published as 10.1136/gut.33.4.466 on 1 April 1992. Downloaded from associated with triglyceride infusion are unusual. gastroduodenal motility, pyloric diameter and gastric Virtually all fluoroscopic studies of the pylorus emptying. QuartJ7 Exp Physiol 1983; 68: 675-86. a in which 2 Shafer RB, Levine AS, Marlette JM, Morley JE. Do calories, have been made during fasting, setting osmolality or calcium determine gastric emptying? Am J localised pyloric contractions do not normally Physiol 1985; 248: R479-83. observations 3 Quigley JP, Zettleman JH, Ivy AC. Analysis of factors occur.2' Consequently, radiological involved in gastric motor inhibition by fats. Am J Physiol have contributed little to the concept that the 1934; 108: 643-51. 4 Weisbrodt NW, Wiley JN, Overholt BF, Bass P. A relation pylorus may play a motor role that is independent between gastroduodenal muscle contractions and gastric of the antrum and duodenum. Our observations emptying. Gut 1969; 10: 543-8. 5 White CM, Poxon V, Alexander-Williams J. Effects of nutri- of the pylorus during delivery of triglyceride to ent liquids on human gastroduodenal motor activity. Gut the duodenum are not unique, since similar 1983; 24: 1109-16. 6 Dooley CP, Reznick JB, Valenzuela JE. Variations in gastric appearances were reported by Cannon in cats and duodenal motility during gastric emptying of liquid when cream was infused into the duodenum.22 meals in humans. Gastroenterology 1984; 87: 1114-9. 7 Fisher RS, Cohen S. Physiological characteristics ofthe human White et al have reported very similar findings to pyloric sphincter. Gastroenterology 1973; 64: 67-75. our own in one healthy human volunteer when 8 Valenzuela JE, Defilippi C. Pyloric sphincter studies in peptic ulcer patients. Dig Dis 1976; 21: 229-32. triglyceride rich barium was ingested.23 9 Kaye MD, Mehta SJ, Showalter JP. Manometric studies ofthe Although the method of our study did not human pylorus. Gastroenterology 1976; 70: 477-80. 10 McShane AJ, O'Morain C, Lennon JR, Coakley JB, Alton BG. allow us to measure transpyloric flow, it was Atraumatic non-distorting pyloric sphincter pressure readily apparent nevertheless that, usually when studies. Gut 1976; 21: 826-8. 11 Tougas G, Allescher H-D, Li YY, Daniel EE, Dent J, Hunt the pylorus was open, transpyloric flow was RH. Effect of duodenal acidification on pyloroduodenal occurring and was especially rapid just before motor activity in humans. Gastroenterology 1988; 94: A464. lumen occlusion by antropyloroduodenal con- 12 White CM, Poxon V, Alexander-Williams. A study of motility tractions. Similarly, pyloric closure consistently of normal human gastroduodenal region. Dig Dis Sci 1981; 26: 609-17. prevented transpyloric flow. Demonstration of 13 Heddle R, Dent J, Toouli J, Read NW. Topography and the capacity of the pylorus to suspend trans- measurement ofpyloric pressure waves and tone in humans. AmJ Physiol 1988; 255: G490-97. pyloric flow does not establish the place, if any, 14 Heddle R, Dent J, Read NW, Houghton LA, Maddern GJ, that the pylorus has in the control of gastric Horowitz M, et al. Antropyloroduodenal motor responses to intraduodenal lipid infusion in healthy volunteers. Am J emptying, but merely establishes that it is a Physiol 1988; 254: G671-9. mechanism that can indeed stop emptying. This 15 Dent J. A new technique for continuous sphincter pressure measurement. Gastroenterology 1976; 71: 263-7. mechanism should be considered as one among 16 Meyer JH. Motility of the stomach and the gastroduodenal several that contribute to slowing of gastric junction. In: Johnson LR, ed. Physiology of the gastro-

intestinal tract (2nd ed). New York: Raven Press, 1987: 613- http://gut.bmj.com/ emptying - the other mechanisms that are 9. currently recognised being fundic relaxation, 17 Ehrlein H-J. Motility of the pyloric sphincter studied by the inductograph method in conscious dogs. AmJ Phvsiol 1988; suppression of antral contractions, and stimula- 254: G650-7. tion of duodenal resistance to flow. During 18 Brody DA, Quigley JP. Application of the 'inductograph' to the registration of movements of body structures such as the emptying of high calorie nutrient liquids and pyloric sphincter. J Lab Clin Med 1944; 29: 863-7. small nutrient solid-liquid meals, IPPWs occur 19 Smith AWM, Code CF, Schlegel JF. Simultaneous cineradiographic and kymographic studies of human gastric interspersed with a mixture of coordinated con- antral motility. J Appl Physiol 1957; 11: 12-16. tractions that involve the antrum, pylorus, and 20 Houghton LA, Read NW, Heddle R, Horowitz M, Collins PJ, on October 3, 2021 by guest. Protected copyright. duodenum.20 These observations and the effect Chatterton B, et al. Relationship of the motor activity of the antrum, pylorus and duodenum to gastric emptying of of pyloroplasty on gastric emptying of nutrients a solid-liquid mixed meal. Gastroenterologv 1988; 94: 1285-91. suggests that the pylorus has an important role in 21 Carlson HC, Code CF, Nelson RA. Motor action of the canine slowing of emptying.2425 The insights into the gastroduodenal junction: a cineradiographic, pressure, and electrical study. AmJ Dig Dis 1966; 11: 155-76. mechanics of pyloric motility gained from the 22 Cannon WB. The movements ofthe stomach studied by means present study will allow systematic investigation of the Roentgen rays. AmJ Physiol 1898; 1: 359-82. of the settings in which the pylorus is of par- 23 White CM, Poxon V, Alexander-Williams. The importance of the distal stomach in gastric emptying ofliquids in man. Surg ticular importance for the control of gastric Gastroenterol 1984; 3: 13-20. emptying. 24 Muller-Lissner SA, Blum A. To-and-fro movements across the canine pylorus. ScandJr Gastro 1984; 19 (Suppl 92): 1-3. 25 Hinder RA, Bremmer CG. Relative role of pyloroplasty size, GT was supported by the CAG-Merck Research Fellowship, the truncal vagotomy, and milk meal volume in canine gastric RMA Scholarship, and the Canadian Medical Research Council. emptying. DigDis 1978; 23: 210-6.