AREGU September 46/3

Ghai, H. S., and L. T. Buck. Acute reduction in whole cell conductance in anoxic turtle brain. Am. J. Physiol. 277 (Regulatory Integrative Comp. Physiol. 46): R887–R893, 1999.—We tested the effect of anoxia, a ‘‘mimic’’ turtle artificial cerebrospinal fluid (aCSF) consisting of high Ca21 and Mg21 concentrations and low pH and adenosine perfusions, on whole cell conductance (Gw) in turtle brain slices using a whole cell voltage-clamp technique. With EGTA in the recording electrode, anoxic or adenosine perfusions did not change Gw significantly (values range between 2.15 6 0.24 and 3.24 6 0.56 nS). However, perfusion with normoxic or anoxic mimic aCSF significantly decreased Gw. High [Ca21] (4.0 or 7.8 mM) perfusions alone could reproduce the changes in Gw found with the mimic perfusions. With the removal of EGTA from the recording electrode, Gw decreased significantly during both anoxic and adenosine perfusions. The A1-receptor agonist N6-cyclopentyladenosine reduced Gw in a dosedependent manner, whereas the A1-receptor specific antagonist 8-cyclopentyl-1,3-dipropylxanthine blocked both the adenosineand anoxic-mediated changes in Gw. These data suggest a mechanism involvingA1-receptor-mediated changes in intracellular [Ca21] that result in acute changes in Gw with the onset of anoxia.