Inositol trisphosphate independent increase of intracellular free calcium and amylase secretion in pancreatic acini.
It is generally believed that the activation of various cell surface receptors results in the phospholipase C-catalyzed production of inositol trisphosphate which, in turn, increases the intracellular concentration of free Ca2+ by stimulating its release from nonmitochondrial sources. We have investigated both the production of inositol trisphosphate and changes in intracellular Ca2+ concentration in rat pancreatic acini in response to caerulein and CCK-JMV-180, two analogs of cholecystokinin. Both of these analogs cause comparable increases in the rate of amylase secretion and in intracellular Ca2+ concentration but their effects on inositol phosphate generation are dramatically different; caerulein stimulates significant production of inositol phosphates within 1 min of its addition, whereas no detectable levels of inositol phosphates were generated within the same time after addition of CCK-JMV-180. These results suggest that the CCK-JMV-180 stimulated release of intracellular Ca2+ is not mediated by inositol trisphosphate but some other as yet unidentified messenger.
Saluja
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AK
Department of Surgery, Beth Israel Hospital, Boston, MA 02215.
Powers
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Steer
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ML
D000681:Amylases / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002108:Ceruletide / Q000494:pharmacology; D007295:Inositol Phosphates / Q000378:metabolism*; D008297:Male; D010179:Pancreas / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D007295:Inositol Phosphates; D002108:Ceruletide; D000681:Amylases; D002118:Calcium