The Influence of Nonrespiratory Alkalosis on Cerebral Blood Flow in Cats

Cerebral blood flow was measured with the 133Xenon clearance method during short-lasting (20 minutes) and more prolonged (90 minutes) infusions of Na2CO3 solutions in anesthetized cats under controlled ventilation. The infusion protocol was regulated so as to produce a given increase in the plasma [HCO3−] in the first 15 minutes, followed by a constant high plasma level for the rest of the infusion period. A high Paco3 level was induced before and at the end of the infusion, when prolonged infusions were made. The results indicate that, in acute experiments (20 minutes), an increase in plasma [HCO3−] of 14 mEq/l does not influence CBF. During more prolonged infusions (90 minutes), an increase of 12 mEq/l produces a reduction of CBF and an increase in the CSF [HCO3−]. These changes are more pronounced when the increase in plasma [HCO3−] is more marked (18 mEq/l).