Glucose and lactate regulate maitotoxin-activated Ca2+ entry in spermatogenic cells: the role of intracellular [Ca2+].

Maitotoxin (MTX), a potent polyether marine biotoxin, induces Ca(2+) entry in different mammalian cells by activation of Ca(2+) channels. The identity and modulation of the MTX-activated Ca(2+) entry pathway is not known. In this work, we show, for the first time, that glucose and lactate can modulate the excitability of spermatogenic cell MTX-activated Ca(2+) channels. Physiological and pharmacological evidences indicate that glucose and lactate differentially affect MTX-activated Ca(2+) entry mainly through changes that these substrates induce on intracellular Ca(2+) stores and the concentration of intracellular Ca(2+) ([Ca(2+)](i)) in spermatogenic cells. Our findings strongly suggest that MTX-activated Ca(2+) channels in spermatogenic cells can be regulated by a Ca(2+)-CaM-dependent protein kinase.