Contractile responses to ouabain and potassium-free solution in vascular tissue from renal hypertensive rats.
This study characterizes contractions to ouabain and potassium-free solution in isolated vascular segments from two-kidney, one clip (2-K, 1C) hypertensive rats. Aorta, mesenteric artery, and vena cava from hypertensive rats were more sensitive (lower threshold) to ouabain than those from normotensive rats. Contractions of hypertensive vascular segments to potassium-free solution and to ouabain (10(-3) mol/l) were faster than those in normotensive vessels. Monensin potentiated contractions to ouabain and increased the rate of force development to potassium-free solution to a greater extent in normotensive aortae than in hypertensive aortae. Amiloride, low sodium solution, verapamil and calcium-free solution depressed contractions to ouabain and potassium-free solution in both hypertensive and normotensive aortae. These observations demonstrate augmented responsiveness to ouabain and potassium-free solution in hypertensive blood vessels. Interventions which influence transmembrane sodium and calcium movements altered contractions to ouabain and potassium-free solution. The results are consistent with the hypothesis that vascular cells of hypertensive rats have enhanced sodium pump activity.
D000818:Animals; D002021:Buffers; D002118:Calcium / Q000494:pharmacology; D006977:Hypertension, Renal / Q000503:physiopathology*; D007473:Ion Channels / Q000378:metabolism; D007552:Isotonic Solutions / Q000494:pharmacology*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000503:physiopathology*; D010042:Ouabain / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism; D014700:Verapamil / Q000494:pharmacology
D002021:Buffers; D007473:Ion Channels; D007552:Isotonic Solutions; C044332:Ringer's solution, potassium-free; D010042:Ouabain; D012964:Sodium; D014700:Verapamil; D002118:Calcium