title: Effects of K-free solution on tension development and Na content in vascular smooth muscles isolated from guinea-pig, rat and rabbit.
abstract: The effects of K-free solution on tension development and cellular Na content were investigated in aortic strips isolated from guinea-pig, rat and rabbit and in rabbit ear artery. Experiments were conducted in the presence of phentolamine (5 X 10(-7) to 10(-6) M) in order to eliminate the possible influence of endogenous catecholamine. K-free solution produced contractions and increased cellular Na content in these vascular smooth muscle preparations. The rate of increase in K-free contraction of rabbit aorta and ear artery was much slower than that of guinea-pig and rat aortae. The rate of accumulation of Na in rabbit arterial smooth muscle preparations was also much slower than that in guinea-pig and rat aortae. When the relationship between tension development and cellular Na content was compared in these arteries, it was found that an increase in cellular Na produced a greater increase in tension in guinea-pig and rat aortae than in rabbit aorta and ear artery. It is suggested that the slow and small responses of rabbit arterial smooth muscles to K-free solution might be due to a slow accumulation of Na and to a smaller role of transmembrane Na gradient in the regulation of cellular Ca.
mesh_terms: D000818:Animals; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000378:metabolism / Q000502:physiology*; D010646:Phentolamine / Q000494:pharmacology; D011188:Potassium / Q000502:physiology*; D011817:Rabbits; D051381:Rats; D012964:Sodium / Q000378:metabolism*; D013045:Species Specificity
chemical_list: D012964:Sodium; D011188:Potassium; D010646:Phentolamine