Cerebral blood flow and metabolic responses to sustained hypercapnia in awake sheep.

摘要: This investigation determined the effects of sustained hypercapnia on cerebral blood flow (CBF; radiolabeled microspheres), metabolic rates for O2 and glucose (CMRO2 CMRglc), brain water content in conscious sheep instrumented with aortic, left ventricular, vena cava, sagittal sinus catheters. PaCO2 was elevated from 38 +/- 3 to 53 (mean SD) mm Hg PaO2 109 7 131 4 96 h an environmental chamber. Hypercapnia did not alter behavior, food intake, arterial pressures, core temperature, or lactate release. Total regional CBF CBF/CMRO2 reached peak values at 1 then readjusted, stabilize lower, but still levels 24 thereafter. CMRO2 CMRglc increased 6 thereafter during hypercapnia. PaCO2, CBF, CMRO2, remained after restoration room air, while returned control value. Frontal occipital lobe wet-to-dry weight ratios modestly significantly hypercapnic exposure. It is concluded that induces stable nonadapting increases both metabolism persist least air association hypoventilization modest elevations water.