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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 [Ca.sup.2+] and [Mg.sup.2+] concentrations and low pH and adenosine perfusions, on whole cell conductance ([G.sub.w]) in turtle brain slices using a whole cell voltage-clamp technique. With EGTA in the recording electrode, anoxic or adenosine perfusions did not change [G.sub.w] significantly (values range between 2.15 [+ or -] 0.24 and 3.24 [+ or -] 0.56 nS). However, perfusion with normoxic or anoxic mimic aCSF significantly decreased [G.sub.w]. High [[Ca.sup.2+]] (4.0 or 7.8 mM) perfusions alone could reproduce the changes in [G.sub.w] found with the mimic perfusions. With the removal of EGTA from the recording electrode, [G.sub.w] decreased significantly during both anoxic and adenosine perfusions. The [A.sub.1]-receptor agonist [N.sub.6]-cyclopentyladenosine reduced [G.sub.w] in a dosedependent manner, whereas the Al-receptor specific antagonist 8-cyclopentyl-1,3-dipropylxanthine blocked both the adenosine-and anoxic-mediated changes in [G.sub.w]. These data suggest a mechanism involving [A.sub.1]-receptor-mediated changes in intracellular [[Ca.sup.2+]] that result in acute changes in [G.sub.w] with the onset of anoxia. calcium; channel arrest; cortical neurons; membrane conductance; western painted turtle