Gut: first published as 10.1136/gut.28.3.330 on 1 March 1987. Downloaded from Guit, 1987, 28, 330-335 Raised serum concentrations of pancreatic enzymes in cigarette smokers M A DUBICK, C N CONTEAS, H T BILLY, A P N MAJUMDAR, AND M C GEOKAS From the Enzymology Research Laboratory, Department ofMedicine, Veterans Administration Medical Center, Martinez, CA, and Departments ofMedicine and Biological Chemistry, University ofCalifornia, Davis, CA, USA SUMMARY Circulating concentrations of digestive enzymes, certain lysosomal hydrolases and protease inhibitors were measured in 19 heavy smokers and 13 non-smokers before (basal) and at 15, 30, and 60 minutes after a single intravenous injection of secretin (75 CU). In smokers, basal serum amylase and immunoreactive pancreatic elastase 2 (IRE2) concentrations were about 100% and 25% higher respectively, than in the non-smokers, whereas, no differences were observed in basal immunoreactive cationic trypsinogen (IRCT) concentrations and in acid phosphatase and f- glucuronidase activities between the two groups. Furthermore, a single injection of secretin to cigarette smokers significantly increased serum amylase, IRCT and IRE2 by 155%, 200%, and 100%, respectively when compared with their corresponding basal levels. No such increment was observed in the non-smokers. In addition, there were no significant differences in serum trypsin or elastase inhibitory capacity or immunoreactive ac,-protease inhibitor and c(2-macroglobulin levels between smokers and non-smokers. The levels and inhibitory capacity of these protease inhibitors was also not affected by secretin injection. These data suggest that cigarette smoking enhances the http://gut.bmj.com/ responsiveness of the exocrine pancreas to a physiological stimulus such as secretin, with resultant substantial increase in the concentrations of pancreatic hydrolases in blood. Cigarette smoking is a well recognised risk factor in injection in cigarette smokers. We have recently the aetiology of pulmonary emphysema,'- coronary shown that exposure of isolated rat pancreatic acini on October 1, 2021 by guest. Protected copyright. artery disease and aortic aneurysms, '7 and has been to nicotine greatly stimulates the secretion of pre- linked to the development of pancreatitis' and formed exportable hydrolases and newly synthesised pancreatic carcinoma. Although the mechanism(s) proteins.'7 18 This observation indicates that nicotine that relate smoking to these diseases are not well exerts a direct effect on the exocrine pancreatic cell. understood, enzymes with elastase-like activity have In addition to nicotine, tobacco smoke also con- been implicated in the pathogenesis of emphysema tains other cytotoxic agents which may affect and aortic aneurysms."zL" exocrine pancreatic function. For example, recent Accumulating evidence suggests that nicotine data from this laboratory demonstrate that acetalde- affects exocrine pancreatic secretion. Several hyde, the primary metabolite of ethanol and a investigators'- have shown that cigarette smoking constituent of tobacco smoke'` inhibits cholecysto- in man or infusion of nicotine in experimental kinin induced amylase release from isolated pan- animals inhibits both basal and secretin mediated creatic acini and the binding of cholecystokinin to stimulation of pancreatic fluid and bicarbonate secre- acinar membranes." tion with no apparent change in protein output. In The present study was undertaken to further contrast, Balldin, et al" have observed raised serum investigate alterations in the responsiveness of the concentrations of amylase, cationic trypsinogen and exocrine pancreas to secretin stimulation and its pancreatic secretory trypsin inhibitor after secretin effect on the protease antiprotease balance in heavy Addres%s for corresplondenece Dr Michael I)Lic;k Depi.rtment of Medicinec cigarette smokers. The circulating levels of digestive (I5IF). VA MediedlCenter, Martinei. (A 94553, USA enzymes, certain lysosomal hydrolases and protease Received fOr publitcation 3 July I986. inhibitors were measured in serum from non- 330 Gut: first published as 10.1136/gut.28.3.330 on 1 March 1987. Downloaded from Circulating enzymes in smokers 33 smokers and heavy smokers of different ages before Hydrolases and after a single iv injection of secretin. Further- [3-glucuronidase and acid phosphatase activity was more, efforts were also made to relate these findings determined colorimetrically according to Sigma to the history of alcohol consumption in the subjects. Technical Bulletins 325 and 104, respectively. 13- glucuronidase activity was expressed a microgram Methods phenolphthalein liberated/h/ml. Acid phosphatase activity was expressed as [tmoles p-nitrophenol SUBJECTS liberated/h/ml. Nineteen smokers (16 men, three women) were recruited from the patients and staff of the VA Gamma-glutamyl transpeptidase Medical Center (Martinez, CA). Except for one Gamma-glutamyl transpeptidase activity was subject, all had smoked for a minimum of eight years assayed by the colorimetric procedure outlined in with a smoking history of 65-7±81 pack years Sigma Technical Bulletin 545. (mean±SEM). The majority smoked at least two packs of cigarettes/day. The subjects ranged in age RADIOIMMUNOASSAYS from 30-68 years (52.2±2.5) and 13 of them con- Serum immunoreactive cationic trypsin(ogen) sumed significant amounts of alcohol regularly. (IRCT) and immunoreactive elastase 2 (IRE2) con- Although coffee consumption was not controlled for centrations were determined by radioimmunoassay this study, Andriulli et al'' found that coffee intake as previously described' except that 0 12% normal did not affect serum trypsin concentrations after rabbit immunoglobulin was removed from the assay secretin injection. Nine young, healthy, volunteer buffer. After a four day incubation at 40C, the students (four men, five women), ranging in age from antigen-antibody complex was precipitated with 25-35 years, served as controls with no history of goat-antirabbit immunoglobulin bound to agarose. A smoking or alcohol abuse. In addition, four male dilution of 1:1 000 000 of specific antiserum to both non-smokers, ranging in age from 53-76 years served enzymes was used. Three appropriate dilutions were as controls to the more aged smokers. Subjects were analysed in duplicate and results were expressed as fasted overnight before testing and the smokers were ng/ml of cationic trypsin(ogen) or elastase 2 by allowed to smoke up to the test period. comparison with purified human cationic trypsin or elastase 2 as standards. BLOOD SAMPLES AND SECRETIN INJECIION http://gut.bmj.com/ Venous blood was obtained before and 15, 30, and 60 OTHER ASSAYS minutes after a single rapid injection (iv over 1 min) The concentrations of immunoreactive a,-protease of 75 CU of secretin (KabiVitrum CB Laboratories, inhibitor (a,-PI) and a2-macroglobulin (a2-M) in Stockholm, Sweden). Blood was allowed to coagu- serum were determined by the rocket immuno- late on ice for at least two hours and serum was electrophoresis procedure of Laurell and McKay.'4 isolated by centrifugation (2000 g, 15 min). Serum Trypsin inhibitory capacity was determined by was stored at -80°C until assayed. incubation of a known amount of purified bovine on October 1, 2021 by guest. Protected copyright. trypsin with serum and measuring the inhibition of ENZYMES AND SUBSTRATES trypsin hydrolysis of TAME.2S Inhibitory capacity Bovine trypsin (EC 3.4.4.4) and porcine pancreatic was assessed from the difference in slope in the elastase (EC 3.4.21.11) were obtained from absence (water blank) and presence of serum. Worthington Biochemical Corp, Freehold, NJ. Elastase inhibitory capacity was measured similarly Porcine pancreatic amylase was a product of by inhibition of the hydrolysis of SLAPNA after Calbiochem-Behring (LaJolla, CA). Tosyl-arginine- incubation of purified pancreatic elastase with methyl ester (TAME) and succinyl-tri-alanine-p- serum.26 nitroanilde (SLAPNA) were from Sigma Chemical Serum albumin concentrations were determined Co (St Louis, MO). Agarose was purchased from by the bromocresol green dye-binding assay (Sigma Biorad Laboratories (Richmond, CA). All reagents Chemical Co). Methemalbumin was assayed by the used for biochemical measurements were of analyti- method of Walberg et al17 and results were expressed cal grade or the purest commercially available. as milligrams haematin/100 ml. ENZYME ASSAYS STATISTICAL ANAL YSIS Amylase Results were analysed by Student's t test for com- Amylase concentrations in serum were determined parison of the means between the smokers and by the method of Jung22 using procion yellow coupled non-smokers and basal and stimulated values within to starch as substrate. groups. Gut: first published as 10.1136/gut.28.3.330 on 1 March 1987. Downloaded from 332 332 ~~~~~~~~~~~~~Dubick,Cont'eas, Billy, Ma]'umdar, and Geokas Results 12LV Amylase c It was observed that both the basal and secretin stimulated levels of amylase and immunoreactive 101 cationic trypsin(ogen) and elastase 2 were similar in 81 both the young and aged non-smokers. Conse- quently, all non-smoking subj'ects were combined mg/mi 6- into a single group. In smokers basal serum amylase and immunoreac- 41- tive elastase 2 concentrations were found to be 100% and 24% higher, respectively, than in the non- 21 smokers (Figure). Serum IRCT concentrations be- tween the two groups were, however, the same (Figure). These observations remained unchanged when the smokers were subdivided according to age