Renal Response to Carbonic Anhydrase Inhibitor in Water-Loaded Intact and Adrenalectomized Rats

¹ From the Department of Physiology, University of North Carolina School of Medicine, Chapel Hill, North Carolina

Renal excretions of water, Na⁺ and K⁺ were determined over a 5-hour period in sham-operated and adrenalectomized male rats injected intraperitoneally with water (5% body wt.) at postoperative intervals of 3, 14, 21 and 28 days. Intact animals maintained fairly constant outputs. In the adrenalectomized group: decreased excretion of water was apparent by 3 days, but was not maximal until after this interval; Na⁺ excretion increased after 14 days and rose progressively; and K⁺ excretion was maximally depressed by 3 days. Diamox (25 mg/100 gm body wt.) increased these values in both groups. The absolute increases in water and K⁺ excretion for the adrenalectomized animals were less than those for the intact animals, while Na⁺ excretion exceeded that of the intact group at the 14-day and subsequent intervals. These data indicate that the diuretic does not completely overcome the increased water reabsorption occurring after adrenalectomy and that the Na⁺—K⁺ exchange mechanism operates at a reduced capacity. Diamox was ineffective in protecting adrenalectomized rats against water intoxication.