Inhibition of Aerobic Respiration of Rat Brain by Desoxycorticosterone in vitro. ∗

Abstract

Summary

(1) The concentration-action relationships of DC and DCG upon aerobic respiration of rat brain cell suspensions indicate:

(a) Increasing amounts of DC and DCG produce increasing amounts of inhibition This relationship is reasonably linear plotting the logarithm of the amount of DC against per cent of inhibition produced.

(b) With increasing amounts of DC a longer period of time is required to attain maximal inhibition while a comparable effect is more rapidly attained with equimolar amounts of the water-soluble conjugate, DCG. The effect, once attained, remains constant without further increase or release of the inhibition.

(c) By this bio-assay the water-solubility of DC at 37.2°C is approximately 3.6×10^-3 Molar.

(2) These data suggest that, under the conditions used, the relatively large amounts of steroid necessary to produce inhibition of aerobic respiration in vitro entirely penetrate or are adsorbed by the affected system. These amounts exceed the concentrations of steroid which will affect other systems in vitro or that occur in living organisms. This does not necessarily exclude the possibility that steroidal inhibition of aerobic respiration may be of significance in the intact organism.