1H AND 31P NMR of Cat Optic Nerve

The ³¹P and ¹H NMR spectra of perchloric acid extracts of cat optic nerve were obtained. Nerves were exposed by lateral orbitotomy, frozen in situ with liquid nitrogen, removed, and extracted.

Resonances from the high energy phosphates adenosine triphosphate and phosphocreatine, and compounds of phospholipid metabolism, such as phosphorylcholine, phosphorylethanolamine, and their glyceryl esters, were observed and assigned in the ³¹P spectrum. The ³¹P spectrum of cat optic nerve ex vivo also was obtained. Resonances from numerous low-molecular-weight compounds including creatine, N-acetyl-aspartate (NAA), inositol, choline, and various amino acids were observed in the ¹H spectrum and assigned by comparison to the spectra of model compounds. The neurotransmitter N-acetylaspartylglutamate (NAAG), previously found in retinal ganglion cells and implicated in the transmission of visual information, was resolved from NAA and observed for the first time by NMR in tissue extracts at a level higher than that of NAA.