Calcium ion uptake in isolated pancreas cells induced by secretagogues

Abstract

1. 1. Secretagogues of pancreatic enzyme secretion: pancreozymin, carbamylcholine, gastrin I, the octapeptide of pancreozymin, caerulein the Ca 2+ inophore A 23187 stimulate 45Ca uptake into isolated rat pancreatic cells, whereas adrenaline, isoproterenol, secretin, dibutyrylic cyclic adenosine 3′,5′-monophospate and dibutyrylic cylic guanosine 3′,5′-monophospate have no effect on 45Ca uptake. 2. 2. A graphical analysis of the Ca 2+ uptake curves reveals at least two phases: a fast phase, probably due to binding of Ca 2+ to the membrane and a slow phase representing Ca 2+ transport into cells. Both phases are stimulated by pancreozymin and carbamylcholine. 3. 3. The 45Ca-exchangeable pool size is increased by both carbamylchloline and pancreozymin, whereas a significant increase of total content of cell calcium was too small to be detected. 4. 4. Atropine blocks the stimulatory effect of carbamylcholine completely but not that of pancreozymin. The Ca 2+ antagonist D600 blocks the stimulatory effects of both carbamylcholine and pancreozymin only partially. 5. 5. The data suggest that secretagogues of pancreatic enzyme secretion act by increasing the rate of Ca 2+ tranfer into the cell most probably through an increase of the cell membrane permeability for Ca 2+.