Exchangeable sodium measured serially in DOC-salt, post-DOC-salt, and Goldblatt hypertension in the rat

A method for serial estimation of exchangeable sodium (NaE) levels in rats was developed and validated. The method can detect differences of 0.5 mmol per rat. The NaE level was found to have a constant relationship to the total body sodium content. Changes in the NaE level were found not to be a necessary accompaniment of two-kidney, one-clip hypertension. The NaE level was increased throughout 6 weeks of one-kidney, one-clip hypertension and reverted to control values with relief of hypertension after unclipping. The NaE level increased during the development of deoxycorticosterone (DOC)-salt hypertension but subsequently decreased during post-DOC-salt hypertension, although blood pressure remained elevated. Thus an increased NaE level was not necessary for the persistence of post-DOC hypertension.