Studies of the Distribution of the Major Cations in Semen and Male Accessory Secretions

Summary. The atomic absorption spectrophotometer provides a simple and easy method for determining sodium, potassium, calcium and magnesium in whole semen, spermatozoa and seminal plasma. Analyses of ram, bull, human, dog, rabbit and fowl semen all reveal a reciprocal relation of potassium to sodium in the spermatozoa and seminal plasma. The high potassium and low sodium concentration of the spermatozoa, coupled with a low potassium and high sodium concentration in the seminal plasma, suggest the operation of a sodium pump mechanism in spermatozoa similar to that postulated for erythrocytes. The magnesium concentration of the spermatozoa always exceeded that of the seminal plasma, whilst the same is true for calcium, except in the bull where the seminal plasma has an exceptionally high calcium content. The distribution of cations between the epididymal spermatozoa and epididymal plasma in the ram and bull is, in general, similar to that between ejaculated spermatozoa and seminal plasma. However, there were substantial differences in absolute values: the sodium concentration of epididymal ram spermatozoa was half that of the ejaculated cells and the potassium concentration about double.