Effect of gamma-aminobutyric acid on pulmonary stretch receptors in the cat

¹ Department of Macrobiology, Research Laboratories, Chas. Pfizer Co., Groton, Connecticut

Studies on the effect of -aminobutyric acid (GABA) on slowly adapting pulmonary stretch receptors of the cat revealed a decrease in sensitivity to stretch, as evidenced by a reduction in firing during inflation of the lungs following drug administration. This phenomenon was characterized by a nonlinear dose effect relationship, a definite effect being observed at 0.1 mg/kg i.v. While immediate respiratory responses to GABA were clearly unrelated to its effect on afferent impulses from the lungs, the increase in depth of respiration following the initial apnea is consistent with desensitization of pulmonary stretch receptors. Further characterization of the effects observed were attempted by studying antagonism of GABA to protoveratrine.