Effects of propofol on extracellular acidification rates in primary cortical cell cultures: Application of silicon microphysiometry to anaesthesia

Abstract

Propofol depresses both cerebral oxygen consumption and glucose utilization. We tested the hypothesis that these well described effects on brain metabolism are manifest by a reduction in neuronal acid production in vitro. The rate of extracellular acidification in primary cell cultures of rat cortical neurones was measured using a novel instrument (silicon microphysiometer) after stimulation with propofol 0.3, 3 and 30 μg ml-1. Intralipid 10% served as a control. Propofol 3 μg ml-1 caused a mean decrease of 1.51 (SEM 0.71)% in baseline acidification rate, which was significantly greater than that produced by 0.3 μg ml-1 or Intralipid alone (P < 0.05). The reduction after stimulation with propofol 30 μg ml-1 was 4.68 (0.35)% of baseline rates and this in turn was significantly greater than that elicited by propofol 3 or 0.3 μg ml-1, or Intralipid (P < 0.001). We have confirmed the depressant effect of propofol on cerebral metabolism and established that propofol inhibits neuronal acid excretion in vitro.