Crystalline lysoplasmalogen (lysophosphatidal choline): preparation from heart muscle and action on erythrocytes and spermatozoa.

When mammalian spermatozoa are washed free from seminal plasma (and thus from fructose) and incubated as suspensions in Ringer solution they remain motile provided that oxygen is present. An explanation of this behaviour was put forward by Lardy & Phillips (1941a, b), who suggested that in the absence of the seminal sugar [later identified by Mann (1946) as fructose] the spermatozoa of bull and ram can derive energy for motility from the oxidative metabolism ofintracellular phospholipids. A study of the lipids present in freeze-dried spermatozoa provided no evidence for the presence of lecithin but showed that the phospholipid fraction consisted mostly of a choline-based plasmalogen (Lovern, Olley, Hartree & Mann, 1957). Subsequently investigations were made into the changes in lipid composition which occur when ram spermatozoa are freed from plasma and incubated as suspensions in Ringer solution (Hartree & Mann, 1958, 1959). The main change observed was a marked decrease in fatty acyl-ester bonds, and from this it was inferred that the reaction responsible for the decrease was the hydrolysis of the sperm plasmalogen to give lysoplasmalogen together with free fatty acid, which, through its oxidative metabolism, could provide the energy necessary to maintain motility. Lysolecithin has already been shown to have a marked inhibitory action upon the respiration of ram spermatozoa (Dawson, Mann & White, 1957). Since choline lysoplasmalogen can be regarded as a possible product of intracellular-lipid metabolism of ram spermatozoa it was decided to prepare this compound and to compare its properties with those of lysolecithin. An ethanolamine lysoplasmalogen was obtained in crystalline formby Feulgen & Bersin (1939), who believed that they had isolated an unmodified muscle plasmalogen, and again by Rapport, Lerner, Alonzo & Franzl (1957), who established the relationship of the crystalline compound to the native ethanolamine plasmalogen of muscle. We have now obtained from ox-heart muscle the corresponding choline lysoplasmalogen in crystalline form and have studied its action upon erythrocytes and upon ram spermatozoa. EXPERIMENTAL