Journal of Dental Research, Vol 74, 1289-1294, Copyright © 1995 by International & American Associations for Dental Research Online Journals
Effects of dopamine on adenylyl cyclase activity and amylase secretion in rat parotid tissue
S. Hatta, N. Amemiya, H. Takemura and H. Ohshika
Department of Pharmacology, School of Medicine, Sapporo Medical University, Japan.
Several previous studies have shown that dopamine causes amylase secretion
from rat parotid tissue. However, the mechanism of this dopamine action is
still unclear. The present study was designed to characterize dopamine
action in rat parotid gland tissue by examining the effects of dopamine on
cyclic AMP accumulation, adenylyl cyclase activity, and amylase release.
Dopamine significantly enhanced accumulation of cyclic AMP in parotid
slices and stimulated adenylyl cyclase activity in parotid membrane
preparations. It also significantly stimulated amylase release from parotid
slices. The stimulatory effects of dopamine on cyclic AMP accumulation,
adenylyl cyclase activity, and amylase release were effectively blocked
with propranolol, a beta-adrenergic antagonist, but not by either SCH
23390, a preferential D1 antagonist, or butaclamol, a preferential D2
antagonist. No substantial specific binding sites for D1 receptors were
detectable by [3H]SCH 23390 binding in parotid membranes. These results
suggest that the stimulatory effect of dopamine on amylase secretion in rat
parotid tissue is not mediated through specific D1 dopamine receptors but
rather through beta-adrenergic receptors.
