THE ELIMINATION OF d-TUBOCURARINE IN THE RAT

¹ Department of Pharmacology, College of Medicine, University of Cincinnati, Cincinnati, Ohio

The elimination of d-tubocurarine was studied in normal, nephrectomized, and eviscerated rats.

(1) After single injections the per cent paralysis produced by a certain dose is predictable, since no striking variation occurs from rat to rat.

(2) With continuous infusion the total paralyzing dose with a given rate of infusion varies considerably, particularly when the rate is low.

(3) The influence of nephrectomy can be detected only in continuous infusion experiments when the rate of administration is relatively low (below 110 micro-gm./kgm. rat/hour).

(4) Eviscerated rats are more sensitive than normal rats to single injections of d-tubocurarine, and in continuous infusion experiments the total paralyzing dose tends to be lower than that for normal rats over the whole range of infusion rates.

(5) After total paralysis the "recovery time" (time between the first reappearance of twitches and the return of maximal contractions) increases when the time of infusion is lengthened.

(6) It is concluded that in rats the elimination of d-tubocurarine by kidney and liver is minor compared with the total elimination as judged by the rapid disappearance of d-tubocurarine from the neuromuscular junction.