Panoramic imaging of brain pH_i and CBF during penicillin and metrazole induced status epilepticus

Using real-time in vivo umbelliferone fluorescent imaging, cortical intracellular brain pH (pH_i) and cortical blood flow (CBF) were measured in New Zealand white rabbits during generalized seizures induced by intravenous metrazole or sodium penicillin. In the former, brain pH_i declined from 7.04 ± 0.07 to 6.78 ± 0.07 within 15 min of generalized seizures and remained at this level for 1 h. In the penicillin group, pH_i fell from 7.05 ±0.10 to 6.81 ±0.07 and also remained at this level over 60 min. This brain acidosis was uniform across the brain's surface. With the onset of status epilepticus there was a hyperemia which occurred in a heterogeneous pattern with blood flow appearing to be greater adjacent to cortical vasculature and slower in border zones between surface blood vessels. In the metrazole group, there was evidence of vasomotor paralysis with loss of autoregulation involving both cortical surface vasculature and penetrating arterioles with their capillary beds.