The Relation of Water and Sodium Excretion to Blood Pressure in Human Subjects

High sodium loads were administered intravenously to a group of subjects whose blood pressures covered a wide range. Despite large individual variations, the water and sodium excretion of the group were found to be significantly and directly correlated with blood pressure. T HE RELATION of salt to hypertension has been the subject of investigation since the report of Ambard and Beau-jard in 1904.1 Over the years, numerous in-vestigators have adduced evidence that high sodium intakes tend to increase blood pres-sure,2-7 while sodium restriction, either by dietary measures,8-14 or ion exchange resin administration'5 16 may be associated with a lowering of pressure, although the number of hypertensive patients who so respond is limited and clinical improvement often exceeds the reduction in pressure."3 14 These relationships have been viewed as evidence that the development or maintenance of essential hypertension may involve the adrenal cortex,'7 ' 1 presumably through the operation of its so-called "sodium retaining" hormones. Surprisingly little attention seems to have been devoted to the exploration of this hypothesis by actual measurements of the rates at which hypertensive patients excrete sodium relative to normotensive controls. Perera and Blood'7 reported that a group of hypertensive patients exhibited a smaller diuresis than a corresponding group of controls during a 24 hour period of salt restriction. Con-siderable overlap was present, however, and the sodium output of the two hypertensives in which this factor was measured was coot different from the output of two normotensive controls. Farnsworth and Barker'9 studied the simultaneous chloride and inulin clearances of 10 hypertensive patients as compared with 12 controls. At comparable filtration rates, th