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Requirement of an extracellular energy substrate for the guinea pig sperm acrosome reaction induced by calcium ionophore
Author(s) -
Bhattacharyya Amitabha,
Pakrashi Anita
Publication year - 1991
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.1080280311
Subject(s) - ionophore , oligomycin , antimycin a , calcium , guinea pig , acrosome reaction , extracellular , biology , acrosome , nigericin , sperm , biochemistry , motility , biophysics , medicine , endocrinology , mitochondrion , microbiology and biotechnology , enzyme , in vitro , atpase , botany , membrane
It is well established that calcium ionophore A 23187 induces acrosome reaction (AcR) of uncapacitated spermatozoa in the presence of extracellular Ca 2+ ions. In the present study, we have investigated how extracellular energy substrates (glucose, pyruvate, and lactate) affect the ionophore‐induced AcR of guinea pig spermatozoa. It was found that 0.3 μM concentration of A 23187 had the maximum effect to initiate AcR of guinea pig spermatozoa. Virtually no spermatozoa underwent their AcR when incubated in substrate‐free modified Tyrode's medium containing 0.3 μM A 23187 and 2 mM Ca 2+ . At least one exogenous substrate is essential for the ionophore‐induced AcR of spermatozoa. As for efficacy of the substrates, lactate was more effective than pyruvate and glucose. However, a better result was observed when lactate was added along with pyruvate. Malonate inhibited the ionophore‐induced AcR but not the hyperactivated motility of spermatozoa. The mitochondrial electron transport chain blockers rotenone, antimycin, and oligomycin failed to inhibit AcR, although in the presence of these blockers spermatozoa were unable to show hyperactivated motility. These results suggest that the mitochondrial citric acid cycle, not the electron transport chain, is probably the energy source for ionophore‐induced AcR of guinea pig spermatozoa.