title: Paradoxical relaxation of arterial strips induced by vasoconstrictive agents.
abstract: Longitudinal strips isolated from canine distributing muscular arteries were relaxed by noradrenaline and contracted by papaverine. This paradoxical relaxation and contraction may be due to a helical and circular arrangement of smooth muscle in the wall which is incompressible. Various vasoconstrictive agents, including noradrenaline, produced a circumferential contraction and longitudinal relaxation in muscular arteries. Vasodilator agents produced the opposite effect. The direction and magnitude of response of a helical strip to a vasoactive substance depended upon its sectioning angle from the transverse axis of the vessel.
mesh_terms: D000241:Adenosine / Q000494:pharmacology; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D004285:Dogs; D004298:Dopamine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D005263:Femoral Artery / Q000187:drug effects; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009638:Norepinephrine / Q000494:pharmacology; D010208:Papaverine / Q000494:pharmacology; D012701:Serotonin / Q000494:pharmacology; D014662:Vasoconstrictor Agents; D014700:Verapamil / Q000494:pharmacology
chemical_list: D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D012701:Serotonin; D014700:Verapamil; D010208:Papaverine; D000241:Adenosine; D001920:Bradykinin; D004298:Dopamine; D009638:Norepinephrine