Quantification of sperm motility by a turbidimetric assay. Correlation to cellular respiration

The turbidimetric method according to SOKOLOSKI et al. (Fertil. Steril. 28, 1337-1341, 1977) was used for quantitative measurement of the motility of washed bovine spermatozoa. The method is based on the registration of the increase in absorbance (A538) which is produced by spermatozoa entering the light path after run from the bottom of a photometer cuvette. This increase in absorbance is dependent on the amount of motile cells and their average velocity. The increase in absorbance related to the total cell concentration was found to be a highly reproducible quantity (motility index M). Inhibitors of dynein ATPase (vanadate) and of the mitochondrial ATP-production (KCN, carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP), oligomycin) produced a diminution of the motility index M in a concentration-dependent manner. Under conditions of oxidative energy metabolism (lactate as substrate) a linear relation between respiration and M existed. Such a relationship was found under treatment of spermatozoa with KCN or vanadate as well as for untreated sperm suspensions. The linear correlation to the respiratory rate justifies to use the proposed motility index as a relative measure of the average motility of a sperm sample.