Respiratory effects of gamma-hydroxybutyric acid in anesthetized rats

Rats lightly anesthetized with halothane were treated with graded intraperitoneal doses of gamma-hydroxybutyric acid (GHBA), a GABA analogue. The drug induced a dose dependent decrease in minute ventilation, mainly due to reduced respiratory frequency. A reduced pH in arterial blood was recorded. GHBA also blunted or abolished the respiratory response to CO2 exposure in a dose-related way. Picrotoxin (0.25, 0.5 or 1.0 mg/kg intravenously), a presumed GABA antagonist did not significantly change the respiratory pattern when given alone but clearly antagonized the GHBA-induced respiratory depression. It is concluded that GABA-ergic mechanisms are involved in central respiratory control.