Referenced in: none

Automatically associated channels: Kv2.1

Title: Calcium-induced vasocontractions after alpha-2 adrenergic receptor activation in the dog saphenous vein: comparison to calcium-induced contractions after potassium-depolarization.

Authors: J Y Lee, R B Warner, M E Brune, J F DeBernardis

Journal, date & volume: Gen. Pharmacol., 1990 , 21, 647-54

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/1980472

Abstract
1. Calcium mediated contractile effects were evoked in phenoxybenzamine (10(-7) M)-pretreated dog saphenous vein (DSV) rings under the continuing presence of norepinephrine (3 x 10(-5) M), a condition that selectively activates alpha 2 (alpha 2)-adrenergic receptors. 2. Calcium-induced contractions in this model were dose-dependently inhibited by the alpha 2 antagonists rauwolscine and SKF-86466, while the calcium channel blockers nifedipine and verapamil produced only small non-dose related inhibitions. The receptor antagonists sulpiride, buspirone, pyrilamine and atropine showed no inhibitory effect. 3. In contrast, rauwolscine and SKF-86466 produced no inhibition of the calcium-evoked contractions in potassium-depolarized DSV rings, in which nifedipine and verapamil exhibited potent calcium antagonist activity. 4. These data provide evidence to support the presence of alpha 2 related receptor-operated calcium channels in vascular smooth muscle, which are pharmacologically distinguishable from potential-dependent calcium channels.