Cytoplasmic Ca2+ gradients evoked by acetylcholine and peptides in pancreatic acinar cells of the guinea-pig.
Cytoplasmic Ca2+ levels ([Ca2+]i) in guinea-pig pancreatic acinar cells stimulated with acetylcholine (ACh) as well as cholecystokinin octapeptide (CCK-8), its analogue CCK-JMV-180, bombesin and substance P (SP) have been compared by confocal Ca2+ imaging. We found that at intermediate and high concentrations all agonists evoked [Ca2+]i waves emanating from the secretory pole of the cell. The [Ca2+]i gradients evoked by ACh and SP were often unidirectional whereas CCK-8- and bombesin-elicited [Ca2+]i responses consisting of [Ca2+]i waves were normally followed by a secondary phase with reversed [Ca2+]i gradients. At low agonist concentrations the [Ca2+]i responses appeared diffuse 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 other peptides. Thus, we found that agonists induced different spatio-temporal patterns of Ca2+ waves in pancreatic acinar cells of the guinea-pig. The reactions evoked by SP and bombesin resembled those evoked by ACh and CCK-8, respectively.
Sjödin
L
L
Department of Physiology, Faculty of Medicine, University of Tokyo, Tokyo 113, Japan.
Ito
K
K
Miyashita
Y
Y
Kasai
H
H
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003593:Cytoplasm / Q000187:drug effects*; D006168:Guinea Pigs; D008297:Male; D010179:Pancreas / Q000187:drug effects*; D010455:Peptides / Q000494:pharmacology*
D010455:Peptides; D000109:Acetylcholine; D002118:Calcium