Effect of Chronic Hypophysectomy and Dexamethasone on Renal Function in Saline Expanded Rats
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We examined the effect of chronic hypophysectomy on renal function of saline expanded rats. We were particularly interested in the sodium excretion, or natriuresis, parameter of renal function. Chronically hypophysectomized rats show no impairment of natriuresis. unlike the acutely hypophysectomized animals reported by Lichardus (1976) and Banks (1978). This return of natriuretic function is believed to be caused by regeneration of the nerve endings of the hypothalamohypophyseal stalk and the resultant return of at least partial posterior pituitary function. Chronically hypophysectomized rats had low, but hypertonic, urine osmolalities. Saline expanded chronically hypophysectomized rats exhibited a glomerular filtration rate lower than that of intact rats, as do expanded, acutely hypophysectomized animals. In contradiction to a prior study by Chabria and Giatonde (1966), we found that dexamethasone has no effect on renal function in saline expanded, intact rats.