and electrolyte content, of the tissues in hypertension. Circulation Researcli 2: 541

AII analysis of the water and electrolyte content of various tissues of rats rendered hypertensive by a period of choline deficiency at the time of weaning indicates that no alterations are induced by this procedure. It is concluded that the hypertensive process, per se, is not necessarily accompanied by changes in the water and electrolyte content of tissues; where such changes are observed, they are probably secondary to paienehyinal renal changes. SEVERAL investigators1"4 have demon-strated an alteration in the water andelectrolyte content of the tissues in hy-pertension. These results have been interpreted by some to indicate that the observed altera-tions, either directly or through some dis-turbance in adrenal cortical function, are responsible for the observed elevation in blood pressure. However, the above-mentioned studies have been performed on animals sub-jected to various manipulations of one and removal usually of the contralateral kidney. Despite the absence of any overt evidence of renal failure, one might consider the observed alterations as evidence of renal dysfunction rather than as part of the hypertensive process, per se. This possibility has been emphasized in particular by Ledingham6 who noted a tendency for the observed abnormalities to disappear with time following the application of a constricting band to one renal artery with removal of the contralateral kidney, despite the maintenance or accentuation of the eleva-tion in blood pressure. The present observations were made on rats rendered hypertensive by subjecting them at the time of weaning to a choline-free diet. This procedure, as shown by Hartcroft and Best,6 results in hypertension when the animals have grown to adult size. The smaller arteries of the kidneys of such animals reveal marked thicken-ing and resemble closely those seen in huma