THE EFFECT OF GAMMA-AMINO-N-BUTYRIC ACID AND SOME RELATED COMPOUNDS ON THE CARDIOVASCULAR SYSTEM OF ANESTHETIZED DOGS

¹ Department of Pharmacology, University of Colorado Medical Center, Denver, Colorado

Gumma-amino-n-butyric acid (GABA), -alanine, 5-amino-n-valeric acid, taurine, sodium butyrate and butylamine induced a transient, dose-relatedm blood pressure fall when administered intravenously to anesthetied dogs.

Respiratory stimulation, a transient pressor response and bradyeardia, all preceding the depressor response, were observed follwoing GABA. The respiratory stimulation was also clicited by -alanine and 5-amino-n-valeric acid.

A more prolonged depressor response was occasionally observed following large doses of 6-amino-n-caproic acid, 8-amino-n-caprylic acid. butylamine also elicited this response in addition to a more transient dose-related depression of blood pressure. Tachyphylaxis to this prolonged blood pressure fall was observed. A 25- to 30- second latency period was needed for the response to be manifest.

-Alanine, 5-amino-n-valeric acid and 6-amino-n-caproic acid antagonized the depress responses induced by GABA.

Evidence is presented which suggests that the depressor response induced in dogs by GABA may be due in part to peripheral autonomic ganglion blockade.

The pressor and respiratory stimulation induced by GABA may be due to carotid and aortic chemoreceptor stimulation.