REDUCED IONIC CONDUCTANCE IN TURTLE BRAIN

Whole cell recording techniques were employed to measure whole cell (G (w)) and specific membrane (G(m)) conductance in turtle and rat pyrami dal neurons in slices. Results indicate that rat neurons are 4.2 times more conductive compared with turtle neurons at 25-degrees-C, which i s accentuated by temperature, so that rat neurons at 37-degrees-C are 22 times more conductive than turtle neurons at 15-degrees-C. A conduc tance Q10 of 1.9 was measured for both turtle (15-25-degrees-C) and ra t (25-35-degrees-C) pyramidal neurons. Conductance measurements of tur tle pyramidal neurons over 6-9 h of anoxia indicate no statistical dif ference between G(m) or G(w) from normoxic control measures. These res ults indirectly support the concept of low ATP-dependent ion pump acti vity in the turtle brain as one mechanism for reduced energy expenditu re in the normoxic state.