The effect of piracetam on the local cortical cerebral blood flow in cats.

The effect of piracetam (2-oxo-1-pyrrolidine-acetamide, Pyramem) on the local cortical cerebral blood flow (CBF) and oxygen balance in the brain was studied on cats anesthetized with ether-chloralose. The changes in local CBF were registered by means of the thermistor thermoclearance technique. pO2 and pCO2 were determined in blood samples from the femoral artery and superior sagittal sinus and arterio-venous differences of O2 and CO2 partial pressures (AVD-O2 and AVD-CO2) were calculated. The experiments were made on normoxic animals and on animals with slight hypoxia. Piracetam administration (100 mg/kg i.v.) leads to an increase in local cortical CBF corresponding to a change in the specific thermoconductivity of the brain of 0.6 . 10(-4) cal . cm-1 . sec-1 . degrees C-1. This effect is observed in 84% of the experiments with normoxia (arterial pO2 96.0 +/- 21.0 mm Hg) and in 40% of the experiments with slight hypoxia (arterial pO2 59.9 +/- 6.0 mm Hg). Changes in AVD-O2 and AVD-CO2 are not observed. Most probably the increase in CBF does not participate in the mechanism of the protective action of piracetam in hypoxia.