Tissue Isotope Clearance. II. Reduction of Clearance by Pentobarbital Infusion 1

Summary

The clearance of a substance from a subcutaneous injection site is influenced by the depth of pentobarbital anesthesia. ¹³¹I-4-iodoantipyrine showed an initial clearance rate of 9.4%/min after subcutaneous injection in anesthetized control female rats. Pentobarbital Na was infused at progressively increasing rates, resulting in a fall in blood pressure proportionate to the dose of barbiturate. With the fall in blood pressure a progressive fall in initial clearance rate of the injected isotope was also noted; after death no further clearance occurred. The data supports Kety's hypothesis that the clearance rate of a rapidly diffusible substance depends upon circulatory efficiency.