Sodium and potassium shifts associated with peripheral resistance changes in the dog.

THE RELATION of cationic distribution to the tonus of vascular smooth muscle has become of increasing interest during the past few years. Acute rises and falls of blood pressure induced by a variety of agents have been shown to be consistently accompanied by inverse shifts of sodium out of or into the extracellular compartment.' Tissue analysis has shown that these movements involve shifts of sodium into and out of vascular smooth muscle cells, usually, but not invariably, associated with inverse potassium transfers.' Manipulation of the ionic environment of vascular tissue either in vitro or in vivo produces well denned changes in the tonus of vascular smooth muscle and underlines the direct relationship between ions and tonus.' 6