Apri l 1 9 9 5 I n t e s t i n a l D isorders A 3 2 7

CAFFEINE AFFECTS THE SYMPTOMS OF LACTOSE INTOLERANCE BUT NOT BREATH HYDROGEN EXCRETION. W. Spivak, M. Yapor and E. Hernandez; Department of Pediatrics, Division of GI & Nutrition,, Montefioi-e Medical Center-Albert Einstein College of Medicine, Bronx, NY

Lactose intolei'anee is a common cause of (3I symptoms such as abdominal discomfort, bloating, diarrhea and flatulence~ Caffeine increases mucosal cyclic AMP and may increase intestinal secretions leading to diarrhea. Since lactose and caffeine are commonly ingested together (e.g. coffee, chocolate, ice cream), we studied 20 patients with suspected lactose intolerance in a double-blind, crossover study to determine if caffeine has an effect on lactose intolerance. After a twenty-four hour very low residue diet and an overnight fast, subjects received either lactose (25g) alone or lactose(25g) plus caffeine (2mg/kg). The test was repeated within 3 weeks in a double-blind crossover fashion. Nine patients were lactose intolerant based on an increase of breath H2 to at least 2Oppm above baseline. All patients with a positive breath test were positive with both lactose alone and caffeine + lactose. Peak H2 levels of 67ppm for the lactose alone and 72ppm for lactose + caffeine occurred between 90-120 minutes for both substrates. Breath hydrogen values did not significantly differ between lactose alone and caffeine + lactose malabsorbers at any time interval, nor was there any evidence from the breath test that transit time was more rapid in either set of substrates. Five patients had higher symptom scores with lactose + caffeine, one patient had a higher symptom score with lactose alone, and three had symptom scores that were similar with both tests. CONCLUSION: Most patients with lactose intolerance have more symptoms when caffeine is ingested with lactose. Caffeine should be limited in patients with symptomatic lactose intolerance who continue to ingest lactose. Hydrogen breath tests do not distinguish between the ingestion of lactose alone and lactose + caffeine.

• STIMULATION OF HUMAN ELECTROGENIC CHLORIDE SECRETION BY NITRIC OXIDE DONORS. W A Stack., B Filipowicz and CJ Hawkcy, Division of Gastroenterology, University Hospital, Queens Medical Centre, Nottingham NG7 2UH, England.

introduction: We have previously demonstrated increased inducible nitric oxide synthase (iNOS) activity in active ulcerative colitis. Since NO has recently been shown to stimulate clectrogenic chloride secretion in rat and guinea pig colon, we have investigated the effect of two NO donors, sodium nitroprusside(SNP) and S-nitroso- acetylpeniciUamine(SNAP) on human colonic ion transport. Methods: Segments of normal human colon obtained surgically were stripped of underlying smooth muscle and mounted in Ussing chambers under voltage clamp conditions. Changes in short circuit current (ASCC) evoked by basolateral application of drugs were compared with paired tissues from the same patient using Student t-test. NO concentration was measured by a redox dependent electrode (World Precision Instruments Iso-NO meter). Results: SNP cause a progressive rise in NO concentration and a concentration dependent transient increase in ASCC over the range i0 -7 to 10-3M (ED50=2.5x10-4M); max ASCC 56.5-+6.9~tA for SNP 10-4M; n=33. SNAP(10-4M) evoked a similar increased ASCC of 37.~-9.61.tA (p=ns compared with SNP10-4M, n=8). Basolateral SNP evoked a greater ASCC than apical 65.9+_24.8 v 14.1+2.0tt,~; n=6, p<0.05. This was attenuated by bumetanide(104M 46%, p<0.05;n=6), in chloride free media(82%, p<0.01; n=6) and reduced by 4-acetamido-4'-isothio-cyano- 2;2'disulphonic acid stillbene(SITS 10-3M, 41%, p=0.139; n=6) an inhibitor of bicarbonate secretion, but not effected by apical amiloride(10"SM). ASCC in response to SNP was also significantly reduced by 62% with the cyclo-oxygenase inhibitor piroxicam(10-5M, p<0.05; n=6), by 57% with the lipoxygenase inhibitor nor- dihydroguaretic acid(10-4M, p<0.05; n=6), by 65% with tetrodotoxin(TTX 10"6M, p<0.05, n=6), an inhibitor of local enteric nerves and abolished with TIX(10-6M) plus piroxicam(10-SM). Conclusion: NO donors stimulate human colonic ion transport in vitro. For SNP, increased ASCC is due at least in part to chloride and possibly bicarbonate secretion, and appears to be transduced through enteric nerves and by local prostanoid synthesis. This study provides evidence that NO may be an important physiological mediator of ion transport in human colon and could contribute to diarrhoea in ulcerative colitis.

MODULATION OF NITRIC OXIDE SYNTHASE ACTIVITY - POSSIBLE CONTRIBUTION TO THE LAXATIVE EFFECT OF BISACODYL AND THE DIARRHEA INDUCED BY COLCHICINE. R. Stalnikowioz. F. Karmeli and D. Rachmilewitz, Department of Medicine, Hadassah University Hospital, Jerusalem, Israel.

The laxative effects of bisacodyl (BIS) and the diarrhea induced by colchicine (CO) are ascribed to their effects on intestinal electrolyte and water transport. We determined the effect of BIS and CO on intestinal nitdc oxide synthase (NOS) activity because inhibition of NO formation was shown to increase epithelial permeability while the mast cell stabilizer, ketotifen (K), attenuates these effects (Gastroenterology 1994; 104:A1044). Rats were treated i.g. with BIS (10 mg/kg) or K (1 mg/kg) or ip. with CO (5 mg/kg), with or without i.g. pretreatment with K 30 min prior to.BIS or CO treatment. Control rats were treated with saline. Rats were sacrificed 4 and 18 h after BIS, 1 and 4 h after CO and 4 h after K. The intestine was isolated, dnsed, the mucosa scraped and NOS activity determined (nmol/g/min). 4 h after administration, BIS decreased significantly jejunal and colonic NOS activity by 25% and 40%. At 18 h NOS activity resumed normal levels. CO induced a significant (26%) decrease in colonic NOS activity after 1 h and 33% decrease in jejunal NOS activity after 4 h. K significantly increased jejunal and colonic NOS activity. K pretreatment prevented the decrease in NOS activity induced by BIS and CO.

TreatmeP.t Time (h) No~ Jejunal NOS Co on c NOS None 4 10-17 2.4+0.6 2.3_+0.2 Ketotifen 4 6 3.3±0.18" 3.9±0.2* Bisacodyl 4 8 1.8±0.1" 1.4~0.2" K + Bisacodyl 4 10 3,1&-O.1 ~ 3.35-0.16"* Bisacodyl 18 8 2.6±0.3 2,3±0.2 Colchicine 1 10 2,3±0.2 1.7±0.04" K + Colchicine 1 5 2.9±0.09 ~ 3.5~0.15 ~ Colchicine 4 10 1.6±0.09" 2.5±0.1 K + Colchicine 4 5 2.5±0.08 ~ 3,3L43.067"*

* significantly different from no treatment (p<0,05); ~ from BIS or CO (p<O.05). Conclusions: 1) The decreased intestinal NOS activity induced by BIS and CO may contribute to their effects on intestinal electrolyte and water transport. 2) The stimulation of intestinal NOS activity by K indicates the possible important contribution of mast cells to the regulation of intestinal permeability.

HEAT SHOCK PROTEIN-72(HSP-72) INDUCTION PROTECTS RAT INTESTINAL MUCOSA FROM ISCHEMIA/REPERFUSION INJURY. A. Stoiadinovic, J. Kiang, R. Smallridge, R. Galloway, T. Shea-Donohue. Depts. Surg. & Meal., USUHS, Div.Med. wRAIR, Bethesda, MD and Wash., D.C.

The objective of this study was to determine whether the induction of HSP-72 is associated with mucosal protection after intestinal ischemia/reperfusion (I/R). Forty-two rats were divided into 6 groups: non-heated (NH) controls; NH- Ischemia(I); NH-I/R; heated (H) controls; H-I; and H-I/R. Rats were pretreated with whole body hyperthermia to a core temperature of 41.5-42°C for 15-20 min. After passive cooling to 39°(3 the rats were subjected either to occlusion of the superior mesenteric artery for 30 min (I), or I followed by 60 min of reperfusion. Small intestinal tissue samples were obtained for HSP-72 (normalized to actin) and leukotriene B 4 (LTB 4 pg/mg protein) assays, and histological assessment to include mucosal injury grading [0(Normal) to 5], villus height/crypt depth ratio (VH/CD), and PMN number/high power field. Synthesis of HSP-72 in the H-control, H-I, & H-I/R groups was significantly greater than that of the corresponding NH groups (table). I/R produced significant mucosal injury in the NH groups, whereas heat stress significantly protected against both l-and I/R-induced injury (p<0.01). Heating was associated with lesser reductions in VH following I (10% v 38%) and I/R (35% v 51%) when compared to corresponding NH groups. PMN infiltration was significantly increased following I and again following I/R in the NH rats but not in 3 heated groups. LT64 production was significantly increased by intestinal I and I/R in the NH rats, whereas LTB41evels were similar among all heated groups. A significant correlation was noted between LTB41evels and PMN infiltration in NH animals (r=0.72, p<0.001), but not in heated groups (r=-0.16). Values are means + SE; *p<0.05 H vs NH; tp<0.05 vs Control.

Event NH-C NH-I NH-I/R H-C H-I H-I/R

HSP-72 .33_+.1 .30-+.1 ,35-+0,1 .96+-.2 * .91-+.2" .73-+.2"

Grade 0.9+,3 4.2,+.1 t 4.2-+.3 t .69-+.8 1.5-+.4" .92-+.2"

VH/CD 2.8-+.2 1.7+-.2 t 1.8-+.2 t 2.6+.2 2.4_+,2* 1.9_+.1 t

PMN 3.2-+.5 9.3+1 t 15-+2 t 1.2-+.4 2.3-+.5" 4.5-+2*

LTB 4 7.3-+2 55-+7 t 130-+30 t 5.9-+2.2 14-+3.7" 10-+2.1 * This study demonstrates that hyperthermia significantly increased the expression of HSP-72 in small intestine, protected against I/R-induced mucosal injury, and decreased PMN infiltration and LTB4PrOduction. These data suggest that HSP-72 exerts its protective effects on intestinal I/R through the inhibition of LTB 4 production and the subsequent prevention of PMN activation and chemokinesis.