Alterations of Phospholipid Metabolism in Rat Cerebral Cortex Mince Induced by Cationic Amphiphilic Drugs

Abstract

Cationic amphiphilic drugs (CAD) of varied clinical use were screened to determine their capacity to alter the pattern of labeling with 32Pi of cerebral cortex mince phospholipids. The altered phospholipid labeling patterns were qualitatively similar, the prominent features being reduced incorporation into phosphatidylcholine and increased incorporation into phosphatidic acid. Relative potencies were as follows: (.+-.)-propranolol > chlorpromazine = 4,4''-bis(diethylaminoethoxy)-.alpha.,.beta.-diethyldiphenylethane > desipramine > dibucaine > pimozide > oxymetazoline = fenfluramine = haloperidol = chloroquine > amphetamine = no drug added. Propranolol was used to study the action of CAD further. Its effect was time- and dose-dependent, but in contrast with pineal gland, no label appeared in phosphatidyl-CMP (CDP-diacylglycerol), nor did dialysis of the mince to reduce diffusible substrates or exogenous addition of substrates cause appearance of liponucleotide. Lack of diffusible precursors is not responsible for CAD effects in vitro. Pulse-chase experiments with 32Pi and [2-3H]glycerol suggested that inhibition of phosphatidate phosphohydrolase may be partly responsible for the observed alterations in phospholipid labeling in the presence of CAD. [Certain CAD are able to induce experimental lipidosis, which is characterized by accumulation of membranous cytoplasmic inclusions of lysosomal nature in tissues.].