Influence of Blood pH on the Susceptibility of Rats to Audiogenic Seizures

Abstract

Wistar rats made acidotic by 200 mg/kg acetazoleamide and alkalotic by 1960 mg/kg, NaHCO3 (both I. P. ), were tested for susceptibility to audiogenic seizures (doorbell method), one hour after injections. In seizure susceptible (SS) rats, the number of seizures was reduced from 17 of 24 trials for controls to 2 of 24, (P=< 0. 001) for acidotic SS rats. Conversely, alkalotic non-susceptible (NS) rats had 35 seizures out of 118 trials, as compared to 1 of 118 for the control NS rats (P=<0. 001). Blood pH measurements one hour after administration of NaHCO3 or acetazoleamide confirmed the expected alkalosis or acidosis. Blood pH and the shift produced by these agents did not differ significantly between the SS and NS rats. This suggests that alkalosis or acidosis per se does not account for differences in seizure susceptibility between SS and NS rats, but that blood pH plays a role in varying the threshold to the seizures.