MITOCHONDRIAL CALCIUM-UPTAKE IN BOVINE FROZEN SPERM

Mitochondria from bovine frozen semen are capable of preserving oxidat ive energy. The purpose of this work was to study calcium uptake by th e inner mitochondrial membrane which, together with the plasmatic memb rane, is involved in spermatic motility and viability regulation. Mito chondrial coupling was confirmed. In the active state, there was a dro p in oxygen uptake rate using calcium concentrations ranging from 20 t o 100 mu M. In the resting state, 75 mu M calcium concentration mimick ed the active respiration state. In both states, concentrations greate r than 100 mu M induced mitochondrial uncoupling. Maximal mitochondria l uptake was recorded in the active state with 10 mu M lactate. At cal cium concentrations greater than 100 mu M, there was a drop in mitocho ndrial calcium uptake for both respiration states. The ability to pres erve oxidative energy allows the spermatozoon to take up mitochondrial calcium, thus regulating its functional activity.