Oxidative metabolism and intracellular calcium variation in capacitated bovine sperm

This report investigates the intracellular calcium Ca-i variation and oxidative processes induced by sperm capacitation with physiologic (heparin) and non physiologic (quercitin) inductors. Differences were observed in Cai in the presence of heparin or quercitin vs controls (p<0.05). CPK activity decreased vs control in samples treated with heparin or quercitin (p<0.05). Heparin samples decreased NADP-IDH activity vs control and quercitin treatment (p<0.05). NADH production due to MDH- and IDH-NAD dependent activity failed to show differences vs heparin- or quecitin-treated samples (p>0.05). The greater CPK activity in controls suggests that part the energy obtained by oxidative phosphorylation may be stored in non-capacitated sperm. NADPH generation during capacitation may occur through MDH and IDH NADP-dependent isoenzymes. Raised Cai and oxidative metabolism would maintain an appropriate ADP/ATP ratio for motility and intracellular signals for bovine sperm capacitation.