Assessment of Intracellular Calcium and Plasmalemmal Membrane Potential in Cryopreserved Metaphase II Mouse Oocytes

Abstract Objectives: Ca2+ is critical for normal oocyte activation and fertilization, and any alteration to the Ca2+ homeostasis may lead to failed fertilization or even cell death. It has been shown that intracellular Ca2+ is increased in bovine and human oocytes when cultured in vitro. Additionally, ATP sensitive potassium channels have been characterised recently in human and Xenopus oocytes. Glibenclamide a KATP channel blocker was shown to protect human oocytes from Ca+2 overloading via inhibition of plasmalemmal KATP channels. This research note aims to demonstrate the effects of oxidative stress and in vitro ageing on the intracellular Ca+2 and plasmalemmal membrane potential dynamics in cryopreserved metaphase II (MII) mouse oocytes. Also, this study aims to show if glibenclamide (a KATP channel blocker ) has a role in regulating intracellular Ca+2 and plasmalemmal membrane potential through KATP channels in cryopreserved metaphase II mouse oocytes.Results: our data did not show an increase in intracellular Ca2+ in untreated cryopreserved mouse oocytes loaded with Fluo-3 AM dye. However, an increase in the plasmalemmal membrane potential was noticed (hyperpolarization). Glibenclamide has shown no significant effect on Ca2+ and plasmalemmal membrane potential.