title: Contribution of extracellular and intracellular calcium to the enhanced effect of an alpha-adrenergic agonist on amylase release from dispersed rat parotid cells.
abstract: The role of calcium in the potentiation of amylase release by the alpha-adrenergic agonist methoxamine (MTX) was examined using dispersed rat parotid acinar cells. The stimulatory effect of MTX (10 microM) on the beta-adrenergic agonist isoproterenol (ISP, 1 microM)-induced amylase release was blocked by the alpha-adrenergic antagonist phentolamine (10 microM). In Ca-free (1 mM EGTA) medium, the increment of amylase release by MTX in normal medium was decreased by about 70%, but MTX still potentiated ISP-induced amylase release. MTX did not affect the cyclic AMP accumulation activated by ISP in either normal or Ca-free medium. MTX enhanced the ISP-stimulated uptake and efflux of 45Ca2+. These results suggest that both extracellular Ca2+ and intracellular stored Ca2+ may play an important role in the potentiation of amylase release from rat parotid acinar cells.
authors.forename: H
authors.initials: H
authors.lastname: Takemura
authors.forename: H
authors.initials: H
authors.lastname: Ohshika
mesh_terms: D000681:Amylases / Q000378:metabolism*; D000818:Animals; D001826:Body Fluids / Q000378:metabolism*; D002118:Calcium / Q000502:physiology*; D000242:Cyclic AMP / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism*; D007424:Intracellular Fluid / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D008729:Methoxamine / Q000494:pharmacology*; D010306:Parotid Gland / Q000201:enzymology* / Q000378:metabolism; D010646:Phentolamine / Q000037:antagonists & inhibitors; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
chemical_list: D000242:Cyclic AMP; D000681:Amylases; D008729:Methoxamine; D007545:Isoproterenol; D002118:Calcium; D010646:Phentolamine