Dopamine inhibits a sustained calcium current through activation of alpha adrenergic receptors and a GTP-binding protein in adult rat sympathetic neurons

LG Aguayo and J Grossie

Section of Electrophysiology, National Institute on Alcohol Abuse and Alcoholism, Rockville, Maryland.

Although it is suspected that dopamine (DA) inhibits a Ca++ current in sympathetic neurons, the receptor and the Ca++ channel type involved are still unknown. We found that DA caused a reversible inhibition on omega-conotoxin sensitive and resistant Ca++ currents in the superior cervical ganglion (SCG). The concentration of DA that induced half- maximal inhibition was 3.0 microM. The DA receptor agonists (+/-)-SKF- 38393 (D1 type) and quinpirole (D2 type) appeared unable to induce an inhibition of the Ca++ current. Furthermore, the receptor antagonists SCH-23390 (D1 type) and (-)-sulpiride (D2 type) did not prevent the inhibitory effect of DA. This suggests that the effect of DA on the Ca++ current was not due to activation of DA receptors. The inhibition of the Ca2++ current by DA was reduced by application of 1 microM phentolamine, a nonselective alpha adrenergic antagonist, and by prazosin and yohimbine, alpha-1 and alpha-2 receptor antagonists, respectively. The beta adrenergic receptor antagonist propranolol did not block the effect of DA. A guanine nucleotide-binding protein appears to be involved in the activation of adrenergic receptors by DA. The addition of GTP-gamma-S (0.1 mM) to the intracellular solution produced an effect similar to that of DA. Incubation of sympathetic neurons with pertussis toxin reduced the effect of DA by 90%. The results indicate that DA reduces the number of available Ca++ channels in sympathetic neurons by activation of alpha adrenergic receptors, which are associated with a pertussis-sensitive GTP-binding protein.

Volume 269, Issue 2, pp. 503-508, 05/01/1994
Copyright © 1994 by American Society for Pharmacology and Experimental Therapeutics

This article has been cited by other articles:

				G. Ding, R. F. Wiegerinck, M. Shen, A. Cojoc, C. M. Zeidenweber, and M. B. Wagner Dopamine increases L-type calcium current more in newborn than adult rabbit cardiomyocytes via D1 and {beta}2 receptors Am J Physiol Heart Circ Physiol, May 1, 2008; 294(5): H2327 - H2335. [Abstract] [Full Text] [PDF]

				C. A. Cornil, J. Balthazart, P. Motte, L. Massotte, and V. Seutin Dopamine Activates Noradrenergic Receptors in the Preoptic Area J. Neurosci., November 1, 2002; 22(21): 9320 - 9330. [Abstract] [Full Text] [PDF]

				J. Behr, T. Gloveli, D. Schmitz, and U. Heinemann Dopamine Depresses Excitatory Synaptic Transmission Onto Rat Subicular Neurons Via Presynaptic D1-Like Dopamine Receptors J Neurophysiol, July 1, 2000; 84(1): 112 - 119. [Abstract] [Full Text] [PDF]

				N. A. Otmakhova and J. E. Lisman Dopamine Selectively Inhibits the Direct Cortical Pathway to the CA1 Hippocampal Region J. Neurosci., February 15, 1999; 19(4): 1437 - 1445. [Abstract] [Full Text] [PDF]