Effect of Angiotonin on the Distribution of Sodium, Potassium and Water in the Rat

STUDIES of ‘Pitressin’ in the bilaterally nephrectomized rat have shown that this extract causes a shift of sodium and water out of the extracellular fluid while potassium moves in 1 . These movements are related to the pressor effect of the extract. Similar shifts are also associated with the pressor effects of epinephrine and norepinephrine 2,3 . With all these agents, reverse shifts occur during the decline of the blood pressure back to normal. Based on our interpretation of these and other similar experiments, we have suggested the theory that the regulation of blood pressure depends, inter alia , on the sodium transfer systems 4 . We have considered potassium to be of less importance than sodium in this regulation, since shifts of this ion are usually considerably less in total amount. This idea is supported by the present findings with angiotonin (hypertensin) in which sodium shifts were not accompanied by any inverse shift of potassium.