Effect of γ-Hydroxybutyrate on the Reactivity of Pial Arteries before and after Ischemia

Abstract

The effect of γ-hydroxybutyrate (GHB) on the reactivity of pial arteries to local metabolic factors was tested in chloralose-anesthetized cats before or after a period of transient ischemia induced by air embolism. The vascular reactions were determined during the perivascular microapplication of artificial CSFs with increasing concentrations of adenosine (10⁻¹¹–10⁻³ M), H⁺ (pH 5.1–7.6), or K⁺ (0–10 m M). During nonischemic conditions the pial arterial reactivity to adenosine and H⁺, but not to K⁺, was significantly increased by GHB (250 mg/kg i.v.) when compared with the control reactivity. After cerebral ischemia the reactivity to adenosine was abolished with and without the administration of GHB prior to air embolism. The reactivity to K⁺ was partly preserved but not increased by GHB when compared with previous results without GHB. In contrast GHB improved the postischemic reactivity to perivascular H⁺ that had been found to be abolished in previous experiments without GHB. The perivascular microapplication of GHB showed no influence of GHB on the vascular diameter. An important finding of the present study is the demonstration of an increase in cerebrovascular reactivity, which may give scope for therapeutic improvement of the regulation of CBF in pathophysiological conditions.