Glycerol metabolism by spermatozoa

Abstract

Ram spermatozoa, separated from seminal plasma by centrifuging and washing, metabolize glycerol aerobically to lactic acid. The yield of lactic acid is higher in the presence than in the absence of phosphate due to an inhibitory effect of phosphate on the oxidation of lactic acid by spermatozoa. Dihydroxyacetone is oxidized by spermatozoa as rapidly as glycerol, giving rise to lactic acid. Phosphoglycerol (both [alpha]- and [beta]-) increases the respiration of spermatozoa. This is due to the oxidation of glycerol set free from phosphoglycerol by dephosphoryla-tion. Glycerylphosphorylcholine, which is a natural constituent of ram semen, is neither dephosphorylated nor oxidized by spermatozoa. Apart from glycerol a number of alcohols and related substances were tested with respect to their effect on respiration. One of them, sorbitol, is oxidized rapidly by spermatozoa to fructose, which is then broken down to lactic acid.