PATHOGENIC EFFECTS OF SALT LOADING IN THE PRESENCE AND ABSENCE OF THE ADRENAL GLANDS

Abstract

This study involved 125 young, sexually mature male rats of the Sprague-Dawley strain. The rats were fed a fluid medium carbohydrate diet to which different amounts of sodium chloride were added. Food-intake was controlled either by tube-feeding or by paired-feeding. Rats having sham-operations, adrenalectomy only, uni-nephrectomy only and adrenalectomy uni-nephrectomy were given salt loads of 4, 12, 16, or 20% (dry weight of diet) for either 56 or 84 days. At the end of the experiment blood-pressure was determined and tissues were prepared for microscopic examination. Uni-nephrectomized rats given high salt loads developed severe hypertension and severe renal-cardiovascular pathology. In similar rats having both kidneys intact the changes from normal were relatively mild but pathogenic effects of salt-loading were still evident. Although adrenalectomy ameliorated the pathogenic effects of salt-loading in the uni-nephrectomized rat some damage did occur; in a few rats the hypertension was marked and the kidney lesions were significantly severe. One such rat showed full-blown hypertensive vascular disease. It is probable that the pathological processes leading to hypertension and arteriosclerosis can go on in the absence of the adrenal cortical hormones. The adrenally insufficient salt-loaded rats drank less water than did comparable rats having the adrenal glands intact. It is postulated that the hormones secreted by the adrenal have some obligatory sodium-retaining action and make the signs of sodium toxicity and related electrolyte imbalances more likely to occur.