The Role of Extracellular Cations in the Development of Myogenic contraction in Isolated Rat Small Arteries

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The purpose of this study was to determine the roles of extracellular cations(Na^+, Ca^<2+> and K^+), membrane K^+ channels and Na^+/K^+ ATPase in the development of myogenic contraction(transmural pressure-induced contraction)in isolated rat skeletal muscle and mesenteric small arteries. The vessels were pressurized under no-flow conditions in a tissue bath. Lumen diameter was measured with a videomicroscopic system. Myogenic contraction was evoked by increasing the lumen pressure from 40 to 100 mmHg. The vessels demonstrated myogenic contraction in low-Na^+(Na^+ 1.18 mmol/L)physiological salt solution(PSS), and this was abolished by removing Ca^<2+> or by applying nifedipine or nisoldipine(10 μmol/L). Neither tetraethylammonium(TEA, 1 mmol/L), Ba^<2+>(10 μmol/L)nor glibenclamide(1 μmol/L)affected the magnitude of the myogenic contraction. K^+ -free PSS and ouabain(0.1 mmol/L)partially depressed myogenic contraction. In conclusion, myogenic contraction was triggered by a cellular process that requires extracellular Ca^<2+> but no Na^+ or K^+. This triggering process is not affected by TEA, Ba^<2+> or glibenclamide.
社団法人日本循環器学会の論文
1996-03-20