Determination of the Steady‐State Intracellular Chloride Concentration in Capacitated Human Spermatozoa

Abstract

ABSTRACT: Chloride channels participate in the mammalian sperm acrosome reaction (AR). However, the mechanism by which sperm regulate intracellular Ch concentration ([Cl−]1) is not known. The steady‐state [Cl−]1, has also never been reported for mammalian spermatozoa. Therefore, using chloride‐sensitive fluorescent dyes, we sought to determine the steady‐state [Cl−]1, of capacitated human spermatozoa by a null‐point measurement technique. We found that the [Cl−]1 was sufficiently elevated (a conservative estimate of ≥41 mM) such that the opening of chloride channels should result in a Ch efflux and, hence, in depolarization. Moreover, the [Cl]1 does not remain constant under varying extracellular Ch concentrations ([Cl]0.