Journal of Dental Research, Vol 64, 881-885, Copyright © 1985 by International & American Associations for Dental Research Online Journals
Contribution of extracellular and intracellular calcium to the enhanced effect of an alpha-adrenergic agonist on amylase release from dispersed rat parotid cells
H. Takemura and H. Ohshika
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.
