AJP - Heart and Circulatory Physiology, Vol 256, Issue 3 626-H629, Copyright © 1989 by American Physiological Society
Dopamine stimulates cAMP production in canine afferent arterioles via DA1 receptors
T. Tamaki, C. E. Hura and R. T. Kunau Jr
Department of Medicine, University of Texas Health Science Center, San Antonio 78284-7882.
Dopamine increases renal blood flow and dilates isolated afferent and
efferent arterioles preconstricted with norepinephrine via dopamine 1 (DA1)
receptors. DA1-receptor stimulation also results in dopamine-induced
elevation of adenosine 3'5'-cyclic monophosphate (cAMP) in dog and rat
renal arteries. The present study was undertaken to determine the effects
of dopamine on cAMP accumulation in isolated canine superficial cortical
afferent arterioles. The effect of Sch 23390, a specific DA1-receptor
antagonist, on dopamine-stimulated cAMP accumulation was also examined.
Forskolin (10(-5) M), a potent stimulator of adenylate cyclase, produced a
greater than 11-fold increase in cAMP production compared with control.
Dopamine produced a dose-dependent increase in cAMP accumulation in
afferent arterioles at concentrations of 10(-4) M and 10(-6) M, Sch 23390
(2 x 10(-4) M) abolished dopamine (10(-4) M)-stimulated cAMP accumulation
in afferent arterioles. The dopamine-induced increase in arteriolar cAMP
accumulation was unaffected by propranolol (10(-4) M). Our results suggest
that dopamine increases cAMP production in afferent arterioles via the DA1
receptor. Increased cAMP production may be responsible for dopamine-induced
vasodilation in the afferent arteriole.
