Mitochondrial calcium uptake in bovine frozen sperm.

Mitochondria from bovine frozen semen are capable of preserving oxidative energy. The purpose of this work was to study calcium uptake by the inner mitochondrial membrane which, together with the plasmatic membrane, is involved in spermatic motility and viability regulation. Mitochondrial coupling was confirmed. In the active state, there was a drop in oxygen uptake rate using calcium concentrations ranging from 20 to 100 microM. In the resting state, 75 microM calcium concentration mimicked the active respiration state. In both states, concentrations greater than 100 microM induced mitochondrial uncoupling. Maximal mitochondrial uptake was recorded in the active state with 10 microM lactate. At calcium concentrations greater than 100 microM, there was a drop in mitochondrial calcium uptake for both respiration states. The ability to preserve oxidative energy allows the spermatozoon to take up mitochondrial calcium, thus regulating its functional activity.