Effect of Barbiturates on Renal Function in the Dog

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Abstract
Na barbital and Na pentobarbital when used in dogs to produce a depth of anesthesia suitable for surgical purposes have no apparent effect on the glomerular filtration rate which remains constant throughout the 5-6-hr. duration of the expt. The overall effective plasma flow decreased 18% during the same interval when compared to the initial control observations. The changes encountered here are not significant when compared to expts. without anesthesia and of the same duration. The filtration fraction tended to increase about 24 % under both anesthetics throughout the observations. Although afferent arteriolar vasoconstriction may be the 1st effect noticed in expts. of short duration (1-2 hrs.), efferent arteriolar vasoconstriction supervenes in expts. of long duration (5-6 hrs.), thereby further increasing renal resistance and decreasing effective plasma flow while a fairly constant glomerular filtration rate is maintained. A reduction of 16 % in Tm PAH value was observed under the anesthetics studied in expts. of 5-6 hrs.[image] duration. The usual decrease was small but consistent. The mechanism by which the Tm is depressed remains obscure. The barbiturates seem to be safe agents to use for renal function studies of short duration, but for expts. of long duration (over 3 hrs.) allowance must be made for their possible effect on CpAH and Tm PAH.