Urine concentration and dilution in hypokalemic and hypercalcemic dogs

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Abstract

The urine-concentrating mechanism was studied in chronic hypokalemia (seven dogs given a low K+, high NaCl diet plus injections of deoxycorticosterone acetate [DOCA]) and chronic hypercalcemia (seven dogs given vitamin D). In the potassium-depleted dogs, muscle, serum, and urine K+ fell markedly, but glomerular filtration rate (GFR) and body weight varied little. Maximum urine osmolality fell in all dogs (mean decrease = 45%); however, solute-free water reabsorption (TCH2O) at high rates of solute excretion remained normal in three of four dogs. Free water excretion (CH2O) increased normally or supranormally as a function of increasing Na+ delivery to Henle's loop in six dogs so tested.

Authors

Cleaves M. Bennett