title: The role of calcium and cyclic AMP in amylase release from isolated rat parotid acinar cells: effect of calcium ionophore A23187.
abstract: The effect of the Ca ionophore A23187 on isoproterenol (ISP)-induced amylase release was investigated using isolated rat parotid acinar cells. A23187 increased amylase release in normal medium but this stimulated effect of A23187 was abolished in Ca-free medium. ISP-induced amylase release was inhibited by A23187 in Ca-free medium but not in normal medium. A23187 did not affect basal levels of cyclic AMP in normal medium or Ca-free medium but reduced the accumulation of cyclic AMP stimulated by ISP in both mediums. Both NaF- and ISP-stimulated activities of adenylate cyclase were reduced in washed membrane fraction prepared from A23187-treated slices of parotid glands. 45Ca2+ uptake stimulated by A23187 markedly increased, reached maximum at 10-20 min and then declined immediately. These results suggest that A23187 decreases the accumulation of cyclic AMP stimulated by ISP and results in an inhibition of ISP-induced amylase release in the absence of extracellular Ca2+, whereas a marked influx of Ca2+ stimulated by A23187 may possibly compensate the decrement of amylase release in the presence of extracellular Ca2+.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000681:Amylases / Q000378:metabolism*; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D000242:Cyclic AMP / Q000502:physiology*; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D008566:Membranes / Q000201:enzymology; D010306:Parotid Gland / Q000166:cytology / Q000201:enzymology*; D051381:Rats
chemical_list: D000001:Calcimycin; D000242:Cyclic AMP; D000681:Amylases; D000262:Adenylyl Cyclases; D007545:Isoproterenol; D002118:Calcium