Alpha-adrenergic and serotonergic receptors and forearm venous compliance in normal human subjects.
The effect of alpha-adrenergic and serotonergic receptor agonists and antagonists on forearm venous capacitance and vascular resistance was studied in normal subjects. Venous volumes were significantly decreased by phenylephrine, an alpha 1-adrenoceptor agonist, and norepinephrine, which stimulates both alpha 1- and alpha 2-adrenoceptors, but not by the alpha 2-adrenoceptor agonist clonidine. Vascular resistance was increased significantly by all three agonists. Both the alpha 2-adrenoceptor antagonist yohimbine and the alpha 1-adrenoceptor antagonist prazosin attenuated the venoconstrictor and vasoconstrictor response to norepinephrine, indicating that both adrenoceptors are present. 5-Hydroxytryptamine significantly decreased venous volumes, while vascular resistance was not affected. Ketanserin, a 5-HT2 and alpha 1-adrenoceptor antagonist, attenuated the venous volume responses to 5-hydroxytryptamine and phenylephrine. It is concluded that there are alpha 1- and alpha 2-adrenoceptors and 5-HT2 receptors in the forearm venous system. However, vasoactive doses of clonidine are not venoconstricting. Forearm veins are sensitive to doses of 5-hydroxytryptamine, which do not change vascular resistance compared to alpha-adrenoceptor agonists, which affect both.
Coffman
J D
JD
Evans Memorial Department of Clinical Research, Boston University Medical Center, Massachusetts.
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000328:Adult; D001810:Blood Volume / Q000187:drug effects; D005260:Female; D005542:Forearm / Q000098:blood supply*; D006801:Humans; D008297:Male; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000502:physiology*; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology*; D012039:Regional Blood Flow / Q000187:drug effects; D012702:Serotonin Antagonists / Q000494:pharmacology; D014655:Vascular Resistance / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D011942:Receptors, Adrenergic, alpha; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists