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Study of orocecal transit and intestinal absorption of starch by H2-CH4 breath test in functional gastrointestinal disorders
G A S T R O E N T E R O L O G Y VoI. 114, No. 4
A428 A G A A B S T R A C T S
• G1743 IS SUPERIOR MESENTERIC ARTERY FLOW INCREASED IN PATIENTS WITH EARLY DUMPING SYNDROME? J. Vecht 1, J.A. van Oostayen 2, C.B.H.W. Lamers 1, A.A.M. Masclee 1. Depts. of IGastroenterology-Hepatology and 2Diagnostic Radiology, Leiden University Medical Center, The Netherlands. Dumping occurs in about 10% of patients after gastric surgery. It has been suggested that early dumping is associated with an abnormal increase in postprandial splanchnic blood flow but controlled data are lacking. We have studied basal and postprandial splanchnic blood flow (Doppler ultrasound) in patients with proven early dumping and in two control groups. The dumping group consisted of patients after Billroth II gastrectomy (n=6; age 51 ± 6 yr; body mass index 22 * 1 kg/m2), the surgical control group consisted of patients after Billroth II gastrectomy without dumping symptoms (n=7; age 58 ± 7 yr; body mass index 23 ± 1 kg/m2) and the third group consisted of healthy controls without previous gastric surgery (n=10; age 52 ± 7 yr; body mass index 23 -+ 1 kg/m2). Blood glucose and heart rate were measured after oral dumping provocation with 50 g glucose in 200 ml. Superior mesenteric artery (SMA) blood flow was measured both basally and 20 min after the glucose ingestion. Basal SMA flow was similar in the three groups 0.36 ± 0.06 l/min (dumping), 0.39 ± 0.05 l/min (surgical controls), 0.43 ± 0.02 l/min (healthy controls). After glucose ingestion SMA flow increased significantly in all groups (p < 0.05). Stimulated SMA flow was not significantly different between dumping patients and surgical controls (1,0 ± 0.2 vs 1.0 ± 0.1 l/rain). However, stimulated SMA flow in both groups after gastric surgery combined was significantly (p < 0.05) higher than in healthy controls (1.0 ± 0.I vs 0.7 ± 0.2 l/min). Conclusion: The systemic symptoms associated with early dumping do not result from increased splanchnic blood flow per se. Patients after gastric surgery have an increased postprandial SMA flow irrespective of the presence of dumping. • G1744 REGULATION OF COLONIC CHLORIDE TRANSPORT BY BILE ACIDS (BA). J, Venkatasubramanian, M. Carlos*, S.G. Nataraja, S. Skaluba, and M.C. Rao, Dept. of Physiology & Biophysics, & *Dept. Of Pediatrics, Univ. of Illinois at Chicago, Chicago, IL 60612. We have shown that the BA, tanrodeoxycholate (TDC) increased CI- transport only in adult, but not in weanling and neonatal rabbit distal colonocytes (Gastro 111:1541). In this study we examined the pathways involved in the action of BA to elucidate the basis of the switch in BA-responsiveness that occurs during post-weaning development. While preliminary results suggest that TDC may increase [Ca2+]~(Gastro:110:A825), studies in a variety of intestinal models have implicated other mediators such as, [cAMP]i, prostaglandins (PG), histamine and protein kinase C (PKC), in the action of BA. A number of these studies use intact epithelia and there is no study where all the pathways were examined in a single model. Therefore we explored these pathways in 24 hr suspension cultures of adult distal colonocytes (n _>4). C1- transport was assessed using the halide-sensitive, fluorescent probe 6-methoxy quinolyl acetoethyl ester and expressed in mM/sec. TDC caused a dose-dependent increase in C1- transport. The BA, taurochenodeoxycholate was as effective as TDC, but tanrocholate had no effect on CI- transport. In all subsequent experiments the maximal dose of 501aM TDC was used. It has been reported that TDC acts via PG in the rat or via histamine in the mouse and in the rabbit colon, histamine-stimulated CItransport is indomethacin(INDO)-sensitive. Therfore, we examined the effects of INDO (llaM) on TDC-induced C1- secretion. INDO did not affect either basal (not shown) or TDC-stimulated CI- secretion (TDC: 2.1 ± 0.12 and TDC + INDO: 1.9_+0.10 mM/sec), As determined by an enzyme-linked immunoassay, TDC did not increase [cAMP] ~ (Basal: 40.9 ± 0.6; TDC: 31.0± 3 fmoles/106 cells) but forskolin stimulated [cAMP] j (114.9± 14). Similarly, exposure of adult distal colonocytes to TDC did not stimulate membrane or cytosolic PKC activity whereas phorbol dibutyrate (llaM) caused a 4-5-fold increase in both fractions. TDC, however, increases [Ca2÷]~ in adult distal but not in the weanling and newborn colonocytes. This pattern is similar to the effects of TDC on CI- transport in colonocytes of the three different age groups (ibid). The lack of response of weanling and newborn to TDC is not due to an immature Ca2+ signaling pathway since the ionophore, A23187 increased both [Ca2+]~ and CI- secretion in colonocytes of all age groups (accomp. Abstr.). In summary, we demonstrate that TDC actions in rabbit distal colon involves increasing [Ca2+]~but not histamine, PGs, cAMP or PKC. Furthermore, TDC has the ability to increase [Ca2+]~only in the adult suggesting that the age-related switch to BA-responsiveness must occur at a level proximal to increasing [Ca2+]~, perhaps at the membrane. Supported by College Research Board, University of Illinois at Chicago
Q G1745
SEGMENTAL DIFFERENCES IN THE REGULATION OF COLONIC CHLORIDE TRANSPORT BY CALCIUM MEDIATORS. J. Venkatasubramanian, N. Neelakantam, S. Skaluba, D. Vidyasagar, and M.C. Rao, Dept. Of Physiology & Biophysics, & *Dept. Of Pediatrics, Univ. of Illinois at Chicago, Chicago, IL 60612. Age-specific and segment-specific differences in colonic ion transport have been shown in intact tissues but few studies have explored whether these are inherent at the level of the colonocytes. We recently showed that bile acids (BA) stimulate Ck transport in adult but not in neonatal colonocytes (Gastro 111: 1541; 110:A825). In this study we examined if there are any segmental differences in the regulation of C1- transport in the different age groups. We used epithelial ceils from the distal and proximal colon of newborn (NB), weanling (WN) and adult (AD) rabbits. Colonocytes were isolated by enzymatic digestion of mucosal epithelium and crypts enriched by differential centrifugation. The cells were cutured for 24 hr and C1- transport assessed using the fluorescent probe 6-methoxy quinolyl acetoethyl ester. Chloride influx is expressed as mM/sec (n=5). In contrast to our findings in the distal colon, TDC did not stimulate CI- transport in the proximal colon of any age group (Basal/TDC:- AD: 0,58 ± 0.09/0.7 ± 0.1; WN: 0.59 ± 0.1/0.62 ± 0.1; NB: 0.52±0.03/ 0.43±0.1). The adult proximal colon was also nonresponsive to tauro-cholate and taurochenodeoxycholate, However, cAMP-dependent CI- transport was stimulated in all age groups (Forskolin:AD: 1.62±0.5; WN: 1.51 ±0.33; NB:l.22±0.1). We reported that TDC increases [Ca2+]~ in the AD but not WN and NB distal colonocytes (ibid). However, TDC did not increase [Ca2+]~, as measured by FURA-2 fluorescence, in the proximal colon of any age group. To test if the lack of responsiveness to BA in the various colonocyte preparations is due to the absence of a Ca2+-dependent secretory mechanism, we examined the effect of Ca2+ ionophores. Since ionomycin gave equivocal results (ibid), we studied the effects of A23187 on [Ca2+]j and CI- transport in AD, WN, and NB distal and proximal colonocytes. A23187 increased [Ca2+]~in all age groups of both segments. In the distal colon, A23187 caused an associated 2-fold increase in C1- transport in all age groups. However, in the proximal colon it increased C1transport (3-fold) only in the adult. Our results demonstrate that the regulation of colonic transport by Ca2÷-dependent modulators is age-and segmentspecific. Increases in [Ca2+]~ and C1- transport are coordinated at all ages in the distal colon, whereas they are not coupled in the proximal colon of the neonate and weanling. Furthermore, the action of BA, a putative Ca2+dependent secretagogue, is restricted to adult distal colonocytes. Based on these results we postulate that the differences in age- and segment-specific cell signaling mechanisms protects the colon from deleterious effects of inappropriate exposure to secretagogues such as that seen in choleretic diarrhea. Supported by College Research Board, University of Illinois at Chicago • G1746 STUDY OF OROCECAL T R A N S I T A N D INTESTINAL ABSORPTION OF S T A R C H B Y H 2 - CH~ BREATH TEST IN FUNCTIONAL GASTROINTESTINAL DISORDERS. M Ventrucci, GM Ubalducci, A Cipolla, M Middonno, MA Panella, E Roda. Dept of Internal Medicine and Gastroenterology; University of Bologna, Italy Studies based on H2 breath tests have shown that a fraction of starch from white bread is malabsorbed in healthy humans. The malabsorbed fraction is dependent on the amount ingested, the composition of the meal, and the individual gastrointestinal (131) handling. Many patients with functional GI disorders experience distress after starch ingestion. Aims: To study H~-CH 4 starch breath test in functional GI disorders and assess whether the occurrence of intolerance of starch depends on alterations of transit or absorption. Patients: 44 patients (functional dyspepsia in 10, irritable bowel syndrome in 19, both in 15). The presence of these conditions was determined by a questionnaire regarding 24 GI symptoms. Seventeen healthy volunteers served as controls. Methods: Breath samples for H2 and CH 4 measurements were taken every 30 min for 9 hours after ingestion of 100 g of starch in the form of white bread. Results are expressed as medians and 10-90th centile ranges. Results: Incomplete absorption of starch (peak rise in breath H2> 10 ppm) was present in 11/17 healthy controls (65%) and in 18/44 patients (41%). Starch ingestion caused GI symptoms in 17 patients (39%). The H2 excretion after starch ingestion (area under the curve) was significantly lower (p < 0.02) in patients (98 ppm.h, 33-295) than in controls (262 ppm.h, 110-1127). The orocecal transit time of starch was significantly longer (p < 0.01) in patients (390 rain, 300-510) than in controls (300 rain, 180-450). H~ output and orocecal transit time of starch did not significantly differ among patients with functional dyspepsia, irritable bowel syndrome or both, or between patients who had symptoms of starch intolerance during the test with respect to those who did not. CH4 production was demonstrated in 16144 patients (36%), of whom 4 were poor H 2 producers. No relationship was found between the H~ and CH4 excretions. Conclusions: In patients with functional GI disorders there is evidence supporting super-efficient absorption of starch, possibly related to a delay in intestinal transit. GI distress after starch ingestion cannot be attributed to excessive H2intestinal production.
A428 A G A A B S T R A C T S
• G1743 IS SUPERIOR MESENTERIC ARTERY FLOW INCREASED IN PATIENTS WITH EARLY DUMPING SYNDROME? J. Vecht 1, J.A. van Oostayen 2, C.B.H.W. Lamers 1, A.A.M. Masclee 1. Depts. of IGastroenterology-Hepatology and 2Diagnostic Radiology, Leiden University Medical Center, The Netherlands. Dumping occurs in about 10% of patients after gastric surgery. It has been suggested that early dumping is associated with an abnormal increase in postprandial splanchnic blood flow but controlled data are lacking. We have studied basal and postprandial splanchnic blood flow (Doppler ultrasound) in patients with proven early dumping and in two control groups. The dumping group consisted of patients after Billroth II gastrectomy (n=6; age 51 ± 6 yr; body mass index 22 * 1 kg/m2), the surgical control group consisted of patients after Billroth II gastrectomy without dumping symptoms (n=7; age 58 ± 7 yr; body mass index 23 ± 1 kg/m2) and the third group consisted of healthy controls without previous gastric surgery (n=10; age 52 ± 7 yr; body mass index 23 -+ 1 kg/m2). Blood glucose and heart rate were measured after oral dumping provocation with 50 g glucose in 200 ml. Superior mesenteric artery (SMA) blood flow was measured both basally and 20 min after the glucose ingestion. Basal SMA flow was similar in the three groups 0.36 ± 0.06 l/min (dumping), 0.39 ± 0.05 l/min (surgical controls), 0.43 ± 0.02 l/min (healthy controls). After glucose ingestion SMA flow increased significantly in all groups (p < 0.05). Stimulated SMA flow was not significantly different between dumping patients and surgical controls (1,0 ± 0.2 vs 1.0 ± 0.1 l/rain). However, stimulated SMA flow in both groups after gastric surgery combined was significantly (p < 0.05) higher than in healthy controls (1.0 ± 0.I vs 0.7 ± 0.2 l/min). Conclusion: The systemic symptoms associated with early dumping do not result from increased splanchnic blood flow per se. Patients after gastric surgery have an increased postprandial SMA flow irrespective of the presence of dumping. • G1744 REGULATION OF COLONIC CHLORIDE TRANSPORT BY BILE ACIDS (BA). J, Venkatasubramanian, M. Carlos*, S.G. Nataraja, S. Skaluba, and M.C. Rao, Dept. of Physiology & Biophysics, & *Dept. Of Pediatrics, Univ. of Illinois at Chicago, Chicago, IL 60612. We have shown that the BA, tanrodeoxycholate (TDC) increased CI- transport only in adult, but not in weanling and neonatal rabbit distal colonocytes (Gastro 111:1541). In this study we examined the pathways involved in the action of BA to elucidate the basis of the switch in BA-responsiveness that occurs during post-weaning development. While preliminary results suggest that TDC may increase [Ca2+]~(Gastro:110:A825), studies in a variety of intestinal models have implicated other mediators such as, [cAMP]i, prostaglandins (PG), histamine and protein kinase C (PKC), in the action of BA. A number of these studies use intact epithelia and there is no study where all the pathways were examined in a single model. Therefore we explored these pathways in 24 hr suspension cultures of adult distal colonocytes (n _>4). C1- transport was assessed using the halide-sensitive, fluorescent probe 6-methoxy quinolyl acetoethyl ester and expressed in mM/sec. TDC caused a dose-dependent increase in C1- transport. The BA, taurochenodeoxycholate was as effective as TDC, but tanrocholate had no effect on CI- transport. In all subsequent experiments the maximal dose of 501aM TDC was used. It has been reported that TDC acts via PG in the rat or via histamine in the mouse and in the rabbit colon, histamine-stimulated CItransport is indomethacin(INDO)-sensitive. Therfore, we examined the effects of INDO (llaM) on TDC-induced C1- secretion. INDO did not affect either basal (not shown) or TDC-stimulated CI- secretion (TDC: 2.1 ± 0.12 and TDC + INDO: 1.9_+0.10 mM/sec), As determined by an enzyme-linked immunoassay, TDC did not increase [cAMP] ~ (Basal: 40.9 ± 0.6; TDC: 31.0± 3 fmoles/106 cells) but forskolin stimulated [cAMP] j (114.9± 14). Similarly, exposure of adult distal colonocytes to TDC did not stimulate membrane or cytosolic PKC activity whereas phorbol dibutyrate (llaM) caused a 4-5-fold increase in both fractions. TDC, however, increases [Ca2÷]~ in adult distal but not in the weanling and newborn colonocytes. This pattern is similar to the effects of TDC on CI- transport in colonocytes of the three different age groups (ibid). The lack of response of weanling and newborn to TDC is not due to an immature Ca2+ signaling pathway since the ionophore, A23187 increased both [Ca2+]~ and CI- secretion in colonocytes of all age groups (accomp. Abstr.). In summary, we demonstrate that TDC actions in rabbit distal colon involves increasing [Ca2+]~but not histamine, PGs, cAMP or PKC. Furthermore, TDC has the ability to increase [Ca2+]~only in the adult suggesting that the age-related switch to BA-responsiveness must occur at a level proximal to increasing [Ca2+]~, perhaps at the membrane. Supported by College Research Board, University of Illinois at Chicago
Q G1745
SEGMENTAL DIFFERENCES IN THE REGULATION OF COLONIC CHLORIDE TRANSPORT BY CALCIUM MEDIATORS. J. Venkatasubramanian, N. Neelakantam, S. Skaluba, D. Vidyasagar, and M.C. Rao, Dept. Of Physiology & Biophysics, & *Dept. Of Pediatrics, Univ. of Illinois at Chicago, Chicago, IL 60612. Age-specific and segment-specific differences in colonic ion transport have been shown in intact tissues but few studies have explored whether these are inherent at the level of the colonocytes. We recently showed that bile acids (BA) stimulate Ck transport in adult but not in neonatal colonocytes (Gastro 111: 1541; 110:A825). In this study we examined if there are any segmental differences in the regulation of C1- transport in the different age groups. We used epithelial ceils from the distal and proximal colon of newborn (NB), weanling (WN) and adult (AD) rabbits. Colonocytes were isolated by enzymatic digestion of mucosal epithelium and crypts enriched by differential centrifugation. The cells were cutured for 24 hr and C1- transport assessed using the fluorescent probe 6-methoxy quinolyl acetoethyl ester. Chloride influx is expressed as mM/sec (n=5). In contrast to our findings in the distal colon, TDC did not stimulate CI- transport in the proximal colon of any age group (Basal/TDC:- AD: 0,58 ± 0.09/0.7 ± 0.1; WN: 0.59 ± 0.1/0.62 ± 0.1; NB: 0.52±0.03/ 0.43±0.1). The adult proximal colon was also nonresponsive to tauro-cholate and taurochenodeoxycholate, However, cAMP-dependent CI- transport was stimulated in all age groups (Forskolin:AD: 1.62±0.5; WN: 1.51 ±0.33; NB:l.22±0.1). We reported that TDC increases [Ca2+]~ in the AD but not WN and NB distal colonocytes (ibid). However, TDC did not increase [Ca2+]~, as measured by FURA-2 fluorescence, in the proximal colon of any age group. To test if the lack of responsiveness to BA in the various colonocyte preparations is due to the absence of a Ca2+-dependent secretory mechanism, we examined the effect of Ca2+ ionophores. Since ionomycin gave equivocal results (ibid), we studied the effects of A23187 on [Ca2+]j and CI- transport in AD, WN, and NB distal and proximal colonocytes. A23187 increased [Ca2+]~in all age groups of both segments. In the distal colon, A23187 caused an associated 2-fold increase in C1- transport in all age groups. However, in the proximal colon it increased C1transport (3-fold) only in the adult. Our results demonstrate that the regulation of colonic transport by Ca2÷-dependent modulators is age-and segmentspecific. Increases in [Ca2+]~ and C1- transport are coordinated at all ages in the distal colon, whereas they are not coupled in the proximal colon of the neonate and weanling. Furthermore, the action of BA, a putative Ca2+dependent secretagogue, is restricted to adult distal colonocytes. Based on these results we postulate that the differences in age- and segment-specific cell signaling mechanisms protects the colon from deleterious effects of inappropriate exposure to secretagogues such as that seen in choleretic diarrhea. Supported by College Research Board, University of Illinois at Chicago • G1746 STUDY OF OROCECAL T R A N S I T A N D INTESTINAL ABSORPTION OF S T A R C H B Y H 2 - CH~ BREATH TEST IN FUNCTIONAL GASTROINTESTINAL DISORDERS. M Ventrucci, GM Ubalducci, A Cipolla, M Middonno, MA Panella, E Roda. Dept of Internal Medicine and Gastroenterology; University of Bologna, Italy Studies based on H2 breath tests have shown that a fraction of starch from white bread is malabsorbed in healthy humans. The malabsorbed fraction is dependent on the amount ingested, the composition of the meal, and the individual gastrointestinal (131) handling. Many patients with functional GI disorders experience distress after starch ingestion. Aims: To study H~-CH 4 starch breath test in functional GI disorders and assess whether the occurrence of intolerance of starch depends on alterations of transit or absorption. Patients: 44 patients (functional dyspepsia in 10, irritable bowel syndrome in 19, both in 15). The presence of these conditions was determined by a questionnaire regarding 24 GI symptoms. Seventeen healthy volunteers served as controls. Methods: Breath samples for H2 and CH 4 measurements were taken every 30 min for 9 hours after ingestion of 100 g of starch in the form of white bread. Results are expressed as medians and 10-90th centile ranges. Results: Incomplete absorption of starch (peak rise in breath H2> 10 ppm) was present in 11/17 healthy controls (65%) and in 18/44 patients (41%). Starch ingestion caused GI symptoms in 17 patients (39%). The H2 excretion after starch ingestion (area under the curve) was significantly lower (p < 0.02) in patients (98 ppm.h, 33-295) than in controls (262 ppm.h, 110-1127). The orocecal transit time of starch was significantly longer (p < 0.01) in patients (390 rain, 300-510) than in controls (300 rain, 180-450). H~ output and orocecal transit time of starch did not significantly differ among patients with functional dyspepsia, irritable bowel syndrome or both, or between patients who had symptoms of starch intolerance during the test with respect to those who did not. CH4 production was demonstrated in 16144 patients (36%), of whom 4 were poor H 2 producers. No relationship was found between the H~ and CH4 excretions. Conclusions: In patients with functional GI disorders there is evidence supporting super-efficient absorption of starch, possibly related to a delay in intestinal transit. GI distress after starch ingestion cannot be attributed to excessive H2intestinal production.