Low affinity cholecystokinin receptor inhibits cholecystokinin- and bombesin-induced oscillations of cytosolic Ca2+ concentration.
We have investigated whether low affinity cholecystokinin (CCK) receptors suppress agonist-induced rises of cytosolic free Ca(2+) concentration ([Ca(2+)]c) in pancreatic acinar cells by using properties of caffeine. A high concentration of caffeine (20 mM) completely blocked inositol 1,4,5-trisphosphate (InsP(3))-induced [Ca(2+)]c rises but spared the InsP(3)-independent long-lasting [Ca(2+)]c oscillations. In the presence of 20 mM caffeine, only high concentrations of CCK, but not bombesin or JMV-180, suppressed the caffeine-resistant CCK or bombesin-induced [Ca(2+)]c oscillations, indicating that low affinity CCK receptors inhibit agonist-induced [Ca(2+)]c oscillations. It could be one of the underlying mechanisms by which low affinity CCK receptors suppress secretion in pancreatic acinar cells.
Lee
Kwang Kook
KK
Department of Physiology, Sungkyunkwan University School of Medicine, 300 Chunchundong, Janganku, Suwon 440-746, South Korea.
Uhm
Dae-Yong
DY
Park
Myoung Kyu
MK
D000818:Animals; D001839:Bombesin / Q000037:antagonists & inhibitors* / Q000502:physiology; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D002766:Cholecystokinin / Q000037:antagonists & inhibitors* / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D011949:Receptors, Cholecystokinin / Q000502:physiology*
D011949:Receptors, Cholecystokinin; D002110:Caffeine; D002766:Cholecystokinin; D001839:Bombesin; D002118:Calcium