- REGPEP 2000
CAFFEINE-ATTENUATED CYTOPLASMIC CALCIUM RESPONSES TO PANCREATIC SECRETAGOGUES ARE INDEPENDENT OF EXTRACELLULAR CALCIUM Sjodin, Lam; Gylfe, Erik Department of Physiology,
of Uppsala, Sweden
The dependence of cytoplasmic calcium responses of guinea-pig pancreatic acinar cells to agonists on extracellular calcium were compared in the presence and absence of caffeine. Cells were obtained after enzymatic digestion of the pancreas, and were dispersed in a Hepes buffer and allowed to attach to a cover glass used as bottom of a superfusion chamber and loaded with the acetoxymethylester of fura-2. The chamber was placed on the stage of an inverted microscope equipped for epifluorescence within a climate box kept at 37 degrees centigrade. The equipment was continuously reading the 3401380 nm fluorescence excitation ratio from individual cells. Stimulation of pancreatic acinar cells with low concentrations of carbachol or cholecystokinin octapeptide (CCK-8)induced oscillations in cytoplasmic calcium concentrations whereas higher concentrations caused sustained elevations. CCK-JMV-180, a partial agonist of CCK-8, evoked oscillations at all concentrations. If cells were deprived of extracellular calcium, the sustained responses to high concentrations of carbachol or CCK-8 were eliminated, whereas the oscillatory reactions to low concentrations of these agonists and to various concentrations of CCK-JMV-180 were little affected. Caffeine at 10 mM transformed the sustained calcium responses to high concentrations of carbachol or CCK-8 into oscillatory reactions, whereas the oscillations in the presence of low concentrations of carbachol were abolished by caffeine. On the other hand, the oscillations evoked by low concentrations of CCK-8 or various concentrations of CCK-JMV-180 were only modestly affected by 10 mM of this xanthine. When cells were superfused with 10 mM caffeine, the cytoplasmic calcium responses to various concentrations of the different agonists were independent of the presence of extracellular calcium. The results suggest that in the presence of caffeine, cytoplasmic calcium elevations in response to agonists are independent of influx of calcium from the medium.
IN THE CONTENTS OF VASOACTIVE INTESTINAL POLYPEPTIDE AT PATHOLOGY OF THE LOWER ESOPHAGEAL SPHINCTER
Poroikova, Marina V; Poroikova, Marina V; Vinnitsky, National Scientific Centre of Surgery, Russia
IN BLOOD OF THE
Vasoactive intestinal polypeptide (VIP) is one of the main neurotransmitters participating in the relaxation of the lower esophageal sphincter (LES). The contents of VIP in blood was investigated in 23 patients with cardiospasm (I group), in 11 patients with gastroesophageal reflux (II group) and in 15 practically healthy persons (group) on an empty stomach and in 45 minutes after functional loadings by meals and sugar, before and after treatment. Basal levels of VIP in II group (41,lO f 8,03 pg/mL) exceeded (p’O,O5) levels of the patients I group (23,31 f 3,07 pg/mL). But basal contents of VIP in blood of these groups of the patients did not differ from the contents of III group (29,85 * 6,49 pg/mL). The levels of VIP in the patients of I group have decreased after loading of sugar (13,44 + 3,39 pg/mL; p