DIFFERENTIAL ACUTE EFFECTS OF ALDOSTERONE, DEXAMETHASONE, AND HYPERKALEMIA AND HYPERKALEMIA ON DISTAL TUBULAR POTASSIUM SECRETION IN THE RAT-KIDNEY
DIFFERENTIAL ACUTE EFFECTS OF ALDOSTERONE, DEXAMETHASONE, AND HYPERKALEMIA AND HYPERKALEMIA ON DISTAL TUBULAR POTASSIUM SECRETION IN THE RAT-KIDNEY
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DOI：
10.1172/jci111598
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发表时间：
1984-01-01
影响因子：
15.9
通讯作者：
GIEBISCH, GH
中科院分区：
文献类型：
--
作者：
FIELD, MJ;STANTON, BA;GIEBISCH, GH
To determine the specific effects on renal K transport of acute elevations in plasma aldosterone, dexamethasone and K concentrations, adrenalectomized rats were studied and prepared such that each factor could be varied independently. Clearance data alone could not be used to deduce the underlying tubular transport effects; each agent was associated with a marked change in urinary flow rate, which may itself have influenced K excretion. A technique of continuous microperfusion was used in vivo, of single superficial distal tubules to evaluate K secretion at constant luminal flow rate during each experimental maneuver. Acute aldosterone infusion was associated with a 90% stimulation of K secretion by microperfused tubules. However, total kidney Na excretion and urinary flow rate were markedly reduced; these factors opposed the direct tubular action of aldosterone, resulting in no net change in the amount of K excreted into the final urine. Conversely, dexamethasone had no direct effect on K secretion by single microperfused tubules, but caused a sharp increase in urinary flow and Na excretion, and secondarily enhanced urinary K excretion by 50%. Hyperkalemia per se stimulated renal K excretion via a direct tubular effect and by increasing urinary flow rate. Urinary K excretion after infusion of each agent represents the net result of direct tubular effects and secondary flow-mediated changes.
