NAD in the Metabolism of Motile Spermatozoa

Abstract

THE difficulty in attempting to correlate the levels of nicotin-amide nucleotide coenzymes with the metabolism of intact animal cells is to distinguish clearly between changes in the coenzyme oxidation-reduction levels which arise from the metabolism of “resting” cells and changes which are associated with other types of cellular activity, such as growth, division and multiplication. Other problems are how to maintain cell viability and what parameters to use in assessing that viability. Spermatozoa are therefore particularly convenient as experimental objects, for they neither grow nor multiply, but can survive for a long time inside and outside the body. Their viability can be checked by quantitative measurements of motility. Furthermore, at least in respect of carbohydrate metabolism, mammalian spermatozoa depend for their supply of energy on extracellular sources, chiefly in the form of fructose which they utilize anaerobically and aerobically, at a rate which is directly and closely related to the degree of sperm motility^1–3. Thus, changes in the concentration of intra-cellular coenzymes during fructolysis are directly attributable to carbohydrate metabolism.