Temperature dependence of intracellular Ca2+ homeostasis in rat meiotic and postmeiotic spermatogenic cells.
The hypothesis that intracellular [Ca2+] is a cell parameter responsive to extreme temperatures in rat meiotic and postmeiotic spermatogenic cells was tested using intracellular fluorescent probes for Ca2+ and pH. In agreement with this hypothesis, extreme temperatures induced a rapid increase of cytosolic [Ca2+] in rat pachytene spermatocytes and round spermatids. Oscillatory changes in temperature can induce oscillations in cytosolic [Ca2+] in these cells. Intracellular [Ca2+] homeostasis in round spermatids was more sensitive to high temperatures compared with pachytene spermatocytes. The calculated activation energies for SERCA ATPase-mediated fluxes in pachytene spermatocytes and round spermatids were 62 and 75 kJ mol(-1), respectively. The activation energies for leak fluxes from intracellular Ca2+ stores were 55 and 68 kJ mol(-1) for pachytene spermatocytes and round spermatids, respectively. Together with changes in cytosolic [Ca2+], round spermatids undergo a decrease in pH(i) at high temperatures. This temperature-induced decrease in pH(i) appears to be partially responsible for the increase in cytosolic [Ca2+] of round spermatids induced by high temperatures. This characteristic of rat meiotic and postmeiotic spermatogenic cells to undergo an increment in cytosolic Ca2+ at temperatures > 33 degrees C can be related to the induction of programmed cell death by high temperatures in these cells.
Herrera
E
E
Instituto de Quimica, Universidad Catolica de Valparaiso, Valparaiso, Chile.
Salas
K
K
Lagos
N
N
Benos
D J
DJ
Reyes
J G
JG
D000818:Animals; D017209:Apoptosis; D002118:Calcium / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism*; D006706:Homeostasis; D006358:Hot Temperature / Q000009:adverse effects*; D006863:Hydrogen-Ion Concentration; D008297:Male; D008540:Meiosis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013087:Spermatids / Q000378:metabolism; D013090:Spermatocytes / Q000378:metabolism; D013094:Spermatozoa / Q000378:metabolism*
D002118:Calcium