Reduced palmitate turnover in brain phospholipids of pentobarbital-anesthetized rats

Our laboratory has reported that pentobarbital-induced anesthesia reduced t he incorporation of intravenously injected radiolabeled palmitic acid into brain phospholipids. To determine if this decrease reflected a pentobarbita l-induced decrease in palmitate turnover in phospholipids, we applied our m ethod and model to study net flux and turnover of palmitate in brain phosph olipids (1). Awake, light and deep pentobarbital (25-70 mg/kg, iv) anesthet ized rats were infused with [9,10-H-3]palmitate over a 5 min period. Brain electrical activity was monitored by electroencephalography. An isoelectric electroencephalogram characterized deep pentobarbital anesthesia. Net inco rporation rates (J(FA,i)) and turnover rates (F-i) of palmitate were calcul ated. J(FA,i) for palmitate incorporated into phospholipids was dramaticall y reduced by pentobarbital treatment in a dose-dependent manner, by 70% and 90% respectively for lightly and deeply anesthetized animals, compared wit h awake controls. Turnover rates for palmitate in total phospholipid and in dividual phospholipid classes were decreased by nearly 70% and 90% for ligh tly and deeply anesthetized animals, respectively. Thus, pentobarbital decr eases, in a dose-dependent manner, the turnover of palmitate in brain phosp holipids. This suggests that palmitate turnover is closely coupled to brain functional activity.