Effects of Cortisone on Renal Sodium Excretion in Rabbits

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Abstract
On both regular and high Na diets, cortisone (100 mg/day) produced massive fluid accumulation with ascites and pleural effusion. Rabbits either died (18 of 40) or were sacrifieced by the 14th day of steroid administration. In animals that survived for 14 days, metabolic balance studies revealed "escape" from the renal Na-retaining action of cortisone after 2-6 days of marked Na retention. Death was frequently associated with right ventricular hypertrophy, pulmonary edema and anasarca. Pulmonary congestion and edema were confirmed by histological studies; myocarditis was not observed. Other findings included decreased hematocrit, rise in systemic venous pressure, decreased renal renin and enlarged kidneys and liver. A similar response in water and electrolyte metabolism occurred during cortisone injection in adrenalectomized animals except that ascites was not as prominent as in intact animals. In striking contrast, 10 mg/ day of desoxycorticosterone acetate (DOCA) produced minimal Na retention on high Na intake; after 12 days of DOCA administration, the animals were sacrificed and found edema free. Comparable hypokalemia was produced in the DOCA and in the cortisone series. Thus, in the rabbit, "escape" from DOCA was observed consistently and Na retention was minimal, whereas with cortisone marked fluid retention occurred and death frequently resulted.