Ca2(+)-dependent amylase secretion from pancreatic acinar cells occurs without activation of phospholipase C linked G-proteins.
We have examined the influence of guanine nucleotides on Ca2(+)-dependent amylase secretion from SLO permeabilized rat pancreatic acini. GTP gamma S (100 microM) stimulated Ca2+ dependent amylase release, decreasing the EC50 for Ca2+ from 1.4 to 0.8 microM. By contrast, GDP (1mM) and dGDP (1mM) inhibited the maximal Ca2(+)-dependent secretory response. Measurement of IP3 liberation showed that Ca2+ stimulation did not increase the activity of phospholipase C (PLC) postulated to be linked to a G-protein termed Gp; GDP and dGDP must therefore be exerting their inhibitory action via a GTP-binding protein distinct from the PLC-linked Gp.
Padfield
P J
PJ
Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510.
Ding
T G
TG
Jamieson
J D
JD
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D004533:Egtazic Acid / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000502:physiology*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology*; D066298:In Vitro Techniques; D007700:Kinetics; D010179:Pancreas / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D051381:Rats; D012844:Sincalide / Q000494:pharmacology; D010738:Type C Phospholipases / Q000378:metabolism*
D016244:Guanosine 5'-O-(3-Thiotriphosphate); D004533:Egtazic Acid; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; D012844:Sincalide; D002118:Calcium