Low-concentration ouabain does not inhibit noradrenaline-induced contraction of human resistance arteries.
1. Using a Mulvany-Halpern myograph to measure changes in isometric tension, we have investigated the effect of ouabain on noradrenaline-induced contraction of human subcutaneous resistance arteries. 2. Low concentrations of ouabain (10 nmol/l or less) were shown not to alter vascular smooth muscle contractility or sensitivity to noradrenaline. 3. In contrast, higher concentrations of ouabain (100 nmol/l or more) were found to depress vascular smooth muscle contractility and to reduce the sensitivity of the noradrenaline concentration-response relationship. 4. These findings may have implications regarding the presence of an endogenous inhibitor of the sodium pump in essential hypertension and in pregnancy-associated hypertension.
Woolfson
R G
RG
Department of Physiology, St Thomas' Hospital, London.
Richards
N T
NT
Poston
L
L
D001158:Arteries; D001693:Biological Transport, Active / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009213:Myography; D009638:Norepinephrine / Q000494:pharmacology*; D010042:Ouabain / Q000008:administration & dosage / Q000494:pharmacology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects*
D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase; D009638:Norepinephrine