Stages of Salt Exchange in Essential Hypertension

The relation of sodium to hypertension remains one of the most fascinating problems in medicine. The results accumulated over a five-year period of study of this relationship are presented in the paper which follows. In these investigations the appetite for salt and the output of sodium under a variety of loading conditions have been correlated with cardiac and renal function and compared with the patterns found in experimental corticoid and renal hypertensions. THE basic enigma of essential hyper-tension remains its pathogenesis. The major forms of animal hypertension, in which the genetic mechanism is set into motion by the experimenter, show many resemblances to the human disease in their functional and architectural derangements. ' Nevertheless, the methods used to induce experimental hyper-tension differ so much, both from one another and from what is known of the spontaneous origin of essential hypertension, as to cast doubt on the validity of pathogenetic or thera-peutic interpretations based on the resultant animal diseases. The purpose of this report is to point out that a common denominator between essential and experimental hypertension is the existence of certain specific patterns of sodium exchange which are correlated with the stage of the disease. Studies of the development of hyper-tension in animals given desoxycorticosterone acetate (DCA) have shown that this disease occurs in two stages.2 The early stage is marked by an elevated sodium and water output, most evident under load, an increased salt appetite, and a progressively rising blood pressure. In the late stage the output under load, as well as the spontaneous salt intake, revert toward normal and the blood pressure stabilizes at a high level.3 When renal hypertension is induced by encapsulation of the kidneys in latex or silk envelopes, early and late stages may b