CYTOPLASMIC CA2-CELLS OF THE GUINEA-PIG( GRADIENTS EVOKED BY ACETYLCHOLINE AND PEPTIDES IN PANCREATIC ACINAR)

Cytoplasmic Ca2+ levels ([Ca2+](i)) in guinea-pig pancreatic acinar ce lls stimulated with acetylcholine (ACh) as well as cholecystokinin oct apeptide (CCK-S), its analogue CCK-JMV-180, bombesin and substance P ( SP) have been compared by confocal Ca2+ imaging, We found that at inte rmediate and high concentrations all agonists evoked [Ca2+](i) waves e manating from the secretory pole of the cell. The [Ca2(+)](i), gradien ts evoked by ACh and SP were often unidirectional whereas CCK-8- and b ombesin-elicited [Ca2+], responses consisting of [Ca2+](i) waves were normally followed by a secondary phase with reversed [Ca2+](i) gradien ts. At low agonist concentrations the [Ca2+](i) responses appeared dif fuse or localized to the granular part of the cells. The lag times to the [Ca2+](i) rises were shorter in response to ACh and SP than for ot her peptides. Thus, we found that agonists induced different spatio-te mporal patterns of Ca2+ waves in pancreatic acinar cells of the guinea -pig. The reactions evoked by SP and bombesin resembled those evoked b y ACh and CCK-8, respectively.