A comparative study of carnitine and acylcarnitine concentration in semen and male reproductive tract fluids.

1. L-carnitine and its short-chain acyl derivatives were measured in semen of boar, man, rooster, bull, squirrel monkey and ram. 2. Carnitine was present in concentrations of 220, 476, 540, 1880, 3330 and 3820 muM respectively, and acetylcarnitine concentrations were 2, 191, 354, 709, 259 and 2750 muM. Propionyl and C4-acyl carnitines were found in small quantities. 3. Analysis of sequential "Split-ejaculate" samples of boar semen showed that carnitine concentration correlated with sperm count, suggesting an epididymal origin for this substance in this species. 4. Bioautographic analysis of samples obtained from ram and rat indicated that carnitine and acetylcarnitine were present in epididymal fluid and in fluids from accessory glands of the male reproductive tract.