Energy metabolism and its linkage to intracellular Ca2+ and pH regulation in rat spermatogenic cells

Energy metabolism and intracellular adenine nucleotides of meiotic and post meiotic spermatogenic cells are highly dependent on external substrates for oxidative phosphorylation and glycolysis. Using fluorescent probes to meas ure the changes in cytosolic [Ca2+] ([Ca2+](i)) and pH (pH(i)), we were abl e to demonstrate that changes in energy metabolism of meiotic and postmeiot ic spermatogenic cells were rapidly translated into changes of pH(i) and [C a2+](i) in the absence or presence of external Ca2+. Under these conditions , mitochondria were gaining cytosolic calcium in these cells. Our results i ndicate that Ca2+ mobilised by changes in metabolic energy pathways origina ted in thapsigargin-sensitive intracellular Ca2+ stores. Changes in intrace llular adenine nucleotides, measured by HPLC, and a likely colocalization o f ATP-producing and Am-consuming processes in the cells seemed to provide t he linkage between metabolic fluxes and the changes in pH(i) and [Ca2+](i) in pachytene spermatocytes and round spermatids. Glucose metabolism produce d an increase of [Ca2+](i) in round spermatids but not in pachytene spermat ocytes, and a decrease in pH(i) in both cell types. Hence, glucose emerges as a molecule that can differentially modulate [Ca2+](i) and pH(i) in pachy tene spermatocytes and round spermatids in rats. (C) 2000 Editions scientif iques et medicales Elsevier SAS.