Role of Hemodynamic Changes in the Increased Cation Excretion after Acute Unilateral Nephrectomy in the Anesthetized Dog

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Abstract

Studies were carried out in anesthetized dogs to characterize the increase in cation excretion which occurs after acute unilateral nephrectomy (AUN). 60 min after AUN, cation excretion had increased from 31.5±2.7 to 66.3±12.0 μeq/min (P < 0.005) and fractional cation excretion had increased from 0.56±0.05 to 1.03±0.14% (P < 0.005), as the glomerular filtration rate was unchanged and renal blood flow fell. The increased cation excretion was accompanied by an increase in fractional phosphate excretion, no change in chloride excretion, and a fall in renin secretion. These alterations in renal function were associated with marked changes in systemic hemodynamics: cardiac output fell from 2.52±0.24 to 1.85±0.16 liters/min (P < 0.001), as diastolic pressure rose without an overall increase in mean arterial pressure, and heart rate fell.

Authors

Michael H. Humphreys, J. Carlos Ayus