DISTRIBUTION OF MEMBRANE PHOSPHOLIPIDS IN THE RABBIT NEURAL RETINA, OPTIC-NERVE HEAD AND OPTIC-NERVE

Since diseases of the neural retina and optic nerve can result in alte ration of biological membranes, this study determines similarities and differences in the membrane phospholipid content of the neural retina , optic nerve head, and optic nerve to serve as baseline data. Neural retina, optic nerve head, and optic nerve were dissected, isolated as 5 sets from 20 rabbits and frozen in liquid N-2. Separate pooled-tissu e extracts were prepared for each set of tissues and phosphorus-31 nuc lear magnetic resonance (P-31 NMR) analyses performed. Ten phospholipi ds were quantified (respective neural retina, optic nerve head, and op tic nerve mole % are given for the 5 major phospholipids detected): ph osphatidylcholine (PC), 44.61, 27.67, 26.40; PC plasmalogen or alkylac yl PC (CPLIP); phosphatidylinositol (PI); sphingomyelin (SM); phosphat idylserine (PS), 12.63, 14.77, 15.09; phosphatidylethanolamine (PE), 2 1.21, 9.59, 8.69; PE plasmalogen (EPLAS), 11.07, 30.96, 33.93; an unid entified (unknown) phospholipid (U) at the chemical-shift value of 0.1 3 ppm; diphosphatidylglycerol (DPG); and phosphatidic acid (PA), 0.46, 2.92, 1.57. Significant differences between the various tissues were determined by the one-way analysis of variance, using a Scheffe range value of P < 0.05. The neural retina in all phospholipids detected exc ept for the uncharacterized (unknown) phospholipid was significantly d ifferent from the optic nerve head tissue. The optic nerve head was si gnificantly different from the optic nerve in PC, CPLIP, PE, EPLAS, U, DPG, and PA. The data provide a baseline for studies on pathologicall y changed neural retina, optic nerve head, and optic nerve.