Neural Control of Blood Pressure following 1,1,1-Trichloroethane Inhalation: A Role of Sympathetic Nervous System

Abstract

The effects of 1,1,1-trichloroethane (1,1,1-TCE) inhalation on arterial blood pressure and renal sympathetic nerve activity were investigated in anesthetized dogs. In acute inhalation experiments, the threshold concentration of 1,1,1-TCE required to produce a decrease in blood pressure was 0.4 to 0.5% in inspired air; moreover, a dose-response relationship between the decrease in blood pressure and 1,1,1-TCE concentration which exceeded the threshold level was observed. In addition, renal nerve activity increased and was associated with a slight decrease in blood pressure following inhalation of relatively low concentrations of 1,1,1-TCE. Following inhalation of relatively high concentrations of 1,1,1-TCE, however, renal nerve activity decreased and was accompanied by a marked decrease in blood pressure. Opposite reactions of renal nerve activity were observed when blood pressure decreased to 70-80 mm Hg following inhalation. It is suggested that systemic hypotension resulting from 1,1,1-TCE inhalation may be controlled by two different reactions of sympathetic nerve activity.