Abstract
Urinary Na excretion following acute peroral water loading was clearly increased in SHRSP and SHR compared with WKY even at the age of 4 weeks before the development of hypertension. Cold exposure before and after adrenal denervation did not affect such water-induced exaggerated natriuresis which, therefore, might possibly be involved in genetic mechanism or disposition to hypertension. Since these hypertensive models are prone to retain Na intracellularly (Yamori: In "Hypertension; Physiopathology and Treatment": 556-581, 1983), acute water loading may enhance urinary Na excretion. This phenomenon observed even in prehypertensive stage can be utilized as a predictor for hypertension in SHR and SHRSP and possibly for essential hypertension in men.
