Effect of sodium ion on contractility of the dog's aortic strip in response to catecholamines

¹ Departments of Physiology and Pharmacology, Medical College of Georgia, Augusta, Georgia

Effect of sodium ion on the dog's aortic strip was determined by measuring the tension produced by the isometric contraction of the strip in response to catecholamines during the incubation in Krebs' solution and in modified Krebs' solution in which the concentration of sodium chloride was varied. It was found that increasing sodium chloride in the solution to a certain amount, itself caused spontaneous contraction of the strip. The subthreshold addition of sodium chloride to Krebs' solution in an amount incapable of causing spontaneous contraction definitely potentiated the contractile response of the strip to a low concentration of catecholamines. Total removal of sodium chloride from Krebs' solution considerably depressed the contractility of the strip in response to catecholamines. It is suggested that sodium may importantly be involved in the development of some type of hypertension.