Adenine nucleotide mediation of fructolysis and motility in bovine epididymal spermatozoa.

Fructolysis is stimulated 3to 5-fold in bovine epididymal spermatozoa when the latter are preincubated with caffeine, theophylline, cyclic adenosine 3’, 5’-monophosphate (CAMP), and N6, 02’-dibutyryl adenosine 3’,5’-monophosphate’((Bt)2CAMP). No increase in fructolysis is observed if phosphodiesterase inhibitors or cyclic nucleotides are added to freshly washed cells or to preincubated cells just before fructolytic assay. The rates of [UJ4C]lactate formation from [U-14C]fructose vary considerably when either the length of incubation or the concentration of these compounds is changed. In either case, increased -fructolysis results in increased motility, decreased ATP levels, and, in most cases, a decreased energy charge of the adenylate pool. The assay of metabolites either with or without caffeine or (Bt)*cAMP suggests that these compounds stimulate fructolysis at the level of glyceraldehyde-3-P dehydrogenase. It is concluded that fructolysis in immotile bovine epididymal sperm is inhibited by ATP whereas the induction of motility alters the composition of the adenylate pool and relieves this inhibition. Finally, it is suggested that differences in glycolytic rates in testicular and ejaculated spermatozoa directly reflect ATP content and indirectly the capacity for motility.