sincalide and 2-aminoethoxydiphenyl-borate

Quercetin, a phytoestrogen and flavonoid, relaxes intestinal and vascular smooth muscle. The purpose of this study was to determine if quercetin had an effect on gallbladder smooth muscle. An in vitro technique was used to determine the effects of quercetin on gallbladder strips and which system(s) mediated the relaxation. Paired t tests were used; differences between means of P < .05 were considered significant. Adding quercetin before cholecystokinin or KCl produced a significant (P < .001) decrease in the amount of tension (0.80 ± 0.04 vs 0.48 ± 0.04 g cholecystokinin octapeptide and 0.8 ± 0.06 vs 0.54 ± 0.05 g KCl, respectively). When the protein kinase C (PKC) inhibitors bisindolymaleimide IV and chelerythrine Cl

Topics: Animals; Arginine; Benzophenanthridines; Boron Compounds; Calcium; Carbazoles; Cyclic AMP-Dependent Protein Kinases; Flavonoids; Gallbladder; Guinea Pigs; In Vitro Techniques; Indoles; Male; Maleimides; Muscle, Smooth; Nitric Oxide; Nitric Oxide Synthase; Potassium Chloride; Protein Kinase C; Protein Kinase Inhibitors; Quercetin; Signal Transduction; Sincalide

In fura-2 loaded isolated mouse pancreatic acinar cells, xanthine oxidase (XOD)-catalyzed reactive oxygen species (ROS) generation caused an increase in the cytosolic Ca(2+) concentration ([Ca(2+)](i)) by release of Ca(2+) from intracellular stores. The ROS-induced Ca(2+) signals showed large variability in shape and time-course and resembled in part Ca(2+) signals in response to physiological secretagogues. ROS-induced Ca(2+) mobilization started at the luminal cell pole and spread towards the basolateral side in a wave manner. ROS-evoked Ca(2+) responses were not inhibited by the phospholipase C (PLC) inhibitor U73122 (10 microM). Neither 2-aminoethoxy-diphenylborate (2-APB) (70 microM) nor ryanodine (50 microM) suppressed ROS-evoked Ca(2+) release. ROS still released Ca(2+) when the endoplasmic reticulum Ca(2+)-ATPase was blocked with thapsigargin (1 microM), or when rotenone (10 microM) was added to release Ca(2+) from mitochondria. Our results suggest that pancreatic acinar cells ROS do not unspecifically affect Ca(2+) homeostasis. ROS primarily affect Ca(2+) stores located in the luminal cell pole, which is also the trigger zone for agonist-induced Ca(2+) signals. Release of Ca(2+) induces Ca(2+) waves carried by Ca(2+)-induced Ca(2+) release and produces thereby global Ca(2+) signals. Under oxidative stress conditions, the increase in [Ca(2+)](i) could be one mechanism contributing to an overstimulation of the cell which could result in cell dysfunction and cell damage.

Topics: Animals; Boron Compounds; Calcium; Cells, Cultured; Cytosol; Enzyme Inhibitors; Estrenes; Fluorescent Dyes; Fura-2; Kinetics; Male; Mice; Pancreas; Pyrrolidinones; Reactive Oxygen Species; Ryanodine; Sincalide; Type C Phospholipases; Xanthine Oxidase

To investigate whether inositol 1,4,5-trisphosphate (IP3) is involved in secretory response of pancreatic acini to cholecystokinin (CCK) analog Boc-Tyr (SO3H)-Nle-Gly-Trp-Nle-Asp-2-phenylethylester.2NH3 (JMV-180).. Dynamics of cytosolic Ca2+ concentration, [Ca2+]c, was recorded by ratiometry of Fura-2 in pancreatic acini.. In perfused preparations of isolated rat pancreatic acinar cells, 2-aminoethoxydiphenylborate (2APB), a new membrane permeant inhibitory modulator of IP3-mediated calcium release from internal stores, inhibited JMV-180-induced [Ca2+]c spikes, and 2APB at 100 mumol.L-1 resulted in an immediate, complete inhibition of the spikes.. Recurrent [Ca2+]c spikes induced by continuous stimulation with JMV-180 are initiated via IP3-mediated Ca2+ release from internal Ca2+ stores.

Topics: Animals; Boron Compounds; Calcium Channels; Calcium Signaling; Cell Separation; Female; Inositol 1,4,5-Trisphosphate; Inositol 1,4,5-Trisphosphate Receptors; Male; Pancreas; Rats; Rats, Sprague-Dawley; Receptors, Cytoplasmic and Nuclear; Sincalide