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Renal actions of dihydroergocristine and of phentolamine in anaesthetized cats
Author(s) -
LOCKETT MARY F.,
WADLEY ROSALIE
Publication year - 1969
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1969.tb08498.x
Subject(s) - phentolamine , endocrinology , chemistry , renal blood flow , medicine , blood pressure , filtration fraction , renal function , chloralose , mean arterial pressure , heart rate , propranolol
1 . Comparison has been made of the effects of dihydroergocristine (DCS) and phentolamine mesylate (phentolamine) on cardiac and respiratory rates, systemic arterial pressure, renal clearances of creatinine (C Cr ) and of p ‐aminohippuric acid (C PAH ) and on the secretion of Na and K, in cats under chloralose anaesthesia. 2 . Phentolamine antagonized vasomotor tone and the pressor effect of circulating noradrenaline to comparable extent. The extent of reduction in urine flow, C Cr , C PAH and Na excretion correlated with the fall in mean arterial pressure. Innervated and denervated kidneys responded similarly. Cardiac and respiratory rates rose slightly as arterial pressure fell. 3 . DCS, 10 to 20 μg/kg per min, did not reduce vasomotor tone, markedly reduced the pressor effect of exogenous noradrenaline, caused bradycardia and respiratory slowing but had little or no effect on renal function. 4 . DCS, 30 to 40 μg/kg per min, lowered mean arterial pressure by 15–25 mm Hg, decreased C PAH but not C Cr , so raising the filtration fraction and caused a small reduction in urine flow and in Na excretion. Innervated and acutely denervated kidneys responded similarly. 5 . DCS, 30 to 40 μg/kg per min, raised mean arterial pressure, decreased C PAH , urine flow and Na excretion but did not alter C Cr in animals pretreated with full α‐adrenergic blocking doses of phentolamine. 6 . DCS, 30 to 40 μg/kg per min, increased the rate of secretion of sympathetic amines from the adrenal medulla and increased the concentration of renin in renal venous blood. 7 . Isolated kidneys perfused at constant pressure from pump‐oxygenator circuits and in saline diuresis responded to DCS (15–17 μg/120 ml. blood) by diuresis and natriuresis and by a rise in the rate of secretion of renin. Higher concentrations of DCS (125–250 μg/120 ml.) were without effect on renal function and did not influence renin secretion. 8 . The renal effects of full α‐adrenergic blocking doses of DCS and of phentolamine were comparable, in the whole animal. 9 . The evidence indicates that the release of noradrenaline by DCS 30–40 μg/kg per min from nerve terminals supplying the juxtaglomerular apparatus may have caused the enhancement of renin secretion.