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      Potassium-Induced Relaxation as an Indicator of Na +-K + ATPase Activity in Vascular Smooth Muscle


      Journal of Vascular Research

      S. Karger AG

      Sodium, Potassium, Ouabain, Rat tail artery, Magnesium, Electrogenic pump

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          Helical strips of rat tail artery were observed to relax in response to potassium after contraction induced by 10<sup>–7</sup> g/ml norepinephrine in potassium-free solution. After several minutes of relaxation, the strips showed an abrupt redevelopment of tension. The amplitude of the potassium-induced relaxation was employed as an index of the activity of the electrogenic sodium-potassium pump and hence of the Na<sup>+</sup>-K<sup>+</sup> ATPase. This assumption seemed justified because the observed amplitude of potassium-induced relaxation paralleled known effects of the following variables on Na<sup>+</sup>-K<sup>+</sup> ATPase: (1) intracellular sodium concentration; (2) ouabain administration; (3) magnesium; (4) temperature, and (5) potassium concentration. The relaxation that occurred in response to potassium is suggested to be due to an enhanced Na<sup>+</sup>-K<sup>+</sup> ATPase resulting in increased electrogenic transport of sodium and potassium and, consequently, hyperpolarization. We propose that potassium-induced relaxation of rat tail artery may be used as a functional indicator of Na<sup>+</sup>-K<sup>+</sup> ATPase activity in vascular smooth muscle.

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          Author and article information

          J Vasc Res
          Journal of Vascular Research
          S. Karger AG
          18 September 2008
          : 15
          : 1-3
          : 198-207
          Department of Physiology, University of Michigan Medical School, Ann Arbor, Mich.
          158166 Blood Vessels 1978;15:198–207
          © 1978 S. Karger AG, Basel

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          Page count
          Pages: 10
          Molecular and Cellular Aspects of Vascular Smooth Muscle in Health and Disease


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