Gut, 1990, 31, 1021-1024 1021 Effect ofulcerative colitis and smoking on rectal blood flow Gut: first published as 10.1136/gut.31.9.1021 on 1 September 1990. Downloaded from E D Srivastava, M A H Russell, C Feyerabend, J Rhodes Abstract flux PF2, PF 110, angle probe, Perimed, Stock- Rectal blood flow was measured by laser holm, Sweden), mounted in portex tubing with doppler flowmetry over 60 minutes in eight an external diameter of 6-6 mm (Fig 1). A side patients with colitis in remission and eight arm was attached at right angles to the probe and healthy male non-smokers. Ten smokers were was taped in the natal cleft to maintain the probe also examined on two occasions, one of which position while records were made. included smoking a cigarette. Plasma nicotine The probe was inserted 5 cm from the anal concentrations were measured in smokers. Ali margin using a modified proctoscope which had subjects showed a pronounced fall in rectal an 8 mm strip cut from the shaft of the scope. blood flow in the first 30 minutes and patients This made it possible to insert the proctoscope, with colitis had significantly higher values visualise clean mucosa on the anterior rectal wall, compared with smokers (p<0002; p<0-04) position the probe, and then withdraw the scope. and non-smokers (p<0O007; p<0002) during Rectal blood flow was measured for 60 the first and second 30 minutes respectively. minutes in each subject and smokers had two sets Values in smokers and non-smokers were of measurements, one of which involved similar, but smoking a cigarette was associated smoking a cigarette at 30 minutes. The order of with a significant fall in blood flow (p<004) these two sessions in smokers was randomised. and this change was inversely related to the All smokers had completed smoking their rise in plasma nicotine concentration cigarette within five minutes and no cigarette had (r= -0-63; p<005). The findings may be been smoked in the previous two hours. Subjects relevant to the association between colitis and smoked their usual brand and were instructed to the smoking history. inhale as deeply as possible. Preliminary studies showed an early pronounced fall in rectal blood flow after the proctoscope was introduced, but The aetiology of ulcerative colitis remains this reached a plateau after 20 to 30 minutes. In unknown, although it is now recognised as a view of this, smokers were asked to have their http://gut.bmj.com/ disease predominantly involving non-smokers' cigarette 30 minutes after the probe was inserted and ex-smokers.' If the smoking status deter- and venous blood was taken for measurement of mines whether ulcerative colitis develops, it is plasma nicotine concentration3 at 30, 35, 40, 45, pertinent to examine mechanisms which may be 50, 55, and 60 minutes; when they did not involved. With this in mind we have examined smoke, samples were taken at 30 and 60 minutes. the effect of smoking on rectal blood flow Ten ml venous blood was taken on each occasion including appropriate controls and patients with via a cannula. on September 28, 2021 by guest. Protected copyright. colitis. STATISTICAL ANALYSIS Methods Standard methods of analysis were used includ- SUBJECTS Eight patients with ulcerative colitis (seven men and one woman, mean age 39 years, range 26-51 years), all non-smokers with distal colitis in remission, were examined; they were receiving sulphasalazine or mesalazine only; eight healthy male non-smokers (mean age 34, range 21-48 years) and 10 healthy men smokers (mean age 45, range 21-66 years), who smoked at least 10 Department of Gastroenterology, cigarettes daily, were also examined. The control University Hospital of subjects, smokers, and non-smokers were receiv- Wales, Heath Park, ing no medication. Preliminary studies showed Cardiff CF4 4XW E D Srivastava that in patients with active ulcerative colitis J Rhodes blood and mucus affected the recording by obliterating the signal, thus only patients with Addiction Research Unit, Institute of Psychiatry, colitis in remission were studied, giving a con- London tinuous uninterrupted reading. M A H Russell C Feyerabend Correspondence to: EXPERIMENTAL DESIGN Figure 1: The probefor measurement ofbloodflow was Professor John Rhodes. mounted in portex tubing with the head 5 cmfrom the anal Accepted for publication Rectal blood flow was measured in volts by laser margin. A side arm was taped in the natal cleft to maintain the 15 November 1989 doppler flowmetry with an angled probe (Peri- position ofthe probe head in relation to mucosa. 1022 Srivastava, Russell, Feyerabend, Rhodes ing paired and unpaired t tests and parametric followed the proctoscopic examination. Blood (Pearson) correlation coefficients. flow in the ulcerative colitis group was consis- tently higher than in the control groups which Gut: first published as 10.1136/gut.31.9.1021 on 1 September 1990. Downloaded from were similar. Smoking was accompanied by a fall Results in the rectal blood flow, which in turn was related Each group of subjects showed a steady fall in to the rise which occurred in the plasma nicotine rectal blood flow which was usually limited to the concentration in individual patients. first 20 minutes. Mean values for patients with The laser doppler technology for measuring ulcerative colitis were higher than for the other mucosal blood flow has proved sensitive and groups throughout the 60 minutes (Fig 2) and reproducible in carefully controlled experi- differences were significant during both the first mental studies in the human colon during (p<0 002) and the second (p<0c04) 30 minute surgery.4 The method has been criticised, how- periods (Table I). ever, because the laser beam penetrates mucosa 6 Blood flow measurements in control subjects, mm, and recorded changes in blood flow may be smokers, and non-smokers were similar and due to changes at different levels which cannot overall values in the first and second 30 minute be quantified. Records are also subject to wide periods did not differ significantly between the variationsfromartefactswhichaccompanymove- groups. Smoking, however, was associated with ment or adjustment ofthe probe. Measurements a significant fall in blood flow of 0-13 volts over a long period, however, with patients in the between 28 and 59 minutes (p<004). During left lateral position gave steady records and experiments where smokers did not smoke there superimposed changes probably reflect rectal was a significant rise after 16 nminutes, wheras the blood flow rather than artefact, which is easily blood flow in non-smokers continued to fall (Fig recognised because of its abrupt nature. The 2). probe was placed over clean mucosa and its After smoking there was a pronounced rise in position within the portex tube ensured that plasma nicotine concentration with peak values while in contact with the mucosa there was a gap between 30 and 35 minutes followed by a steady of 2 mm between the probe surface and the fall over the remaining 25 minutes (Fig 3). When mucosa. subjects were not smoking there was no signifi- The equipment had a signal level indicator and cant change in the plasma nicotine concentration a lamp which changed colour when the probe between 30 and 60 minutes. The maximum fall position was more than 6 mm from the mucosal in mucosal blood flow was related to the maxi- surface, but this rarely occurred. Records over a mum rise in plasma nicotine concentration (r= - long period made it possible to achieve a stable 0-63; p<005; Figure 4) but was not related to measurement of mucosal blood flow. All colitis the peak or mean concentrations of nicotine patients were in remission and after preliminary between 30 to 60 minutes. work our records were made in a standardised http://gut.bmj.com/ manner to limit variations which might invali- date the findings. After smoking the rectal blood Discussion flow did not fall in all subjects, but falls that The consistent fall in rectal blood flow which occurred were related to rises in plasma nicotine occurred in the first 20 to 30 minutes probably concentration; in six subjects the fall was be- reflects a return to normal of changes which tween -0-02 volts and -0-28 volts and asso- ciated with a rise in the plasma nicotine concen- on September 28, 2021 by guest. Protected copyright. tration of over 22 ng/ml. Among four subjects 1.1 whose rectal blood flow did not fall, the nicotine concentrations rose in two but showed only minor change in the other two. The mean peak 1.0 plasma concentrations of nicotine were higher than previously reported' (Table II), which may be due to the subjects smoking the cigarette iI quickly (within five minutes) with blood levels h 0.9- recorded while smoking; initial measurements 0 are usually delayed until two minutes after Ulcerative colitis completion ofsmoking. 3 0.8 Rectal blood flow in smokers was higher in the first 30 minutes before a cigarette was smoked 0 Smokers 0 than in experiments where subjects did not m 0.7 smoke; we can only suggest that the increase which was observed in four ofthe subjects before - Smokers smoking may be some form of anticipatory 0.6- smoking phenomenon comparable with salivation before eating food. This suggestion is made because there was no significant difference in plasma 0.5 nicotine concentration at 30 minutes in the two 10 20 30 40 50 60 series of experiments with smokers. The fall in blood flow which followed smoking appeared to Time (min) be independent of any rise in blood flow before Figure 2: Mean rectal bloodflow measured with a laser dopplerprobe and recorded in volts continuously over 60 minutes in eight patients with ulcerative colitis, eight healthy male smoking.