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

Maitotoxin (MTX), a potent polyether marine biotoxin, induces Ca²⁺ entry in different mammalian cells by activation of Ca²⁺ channels. The identity and modulation of the MTX-activated Ca²⁺ 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 Ca²⁺ channels. Physiological and pharmacological evidences indicate that glucose and lactate differentially affect MTX-activated Ca²⁺ entry mainly through changes that these substrates induce on intracellular Ca²⁺ stores and the concentration of intracellular Ca²⁺ ([Ca²⁺]_i) in spermatogenic cells. Our findings strongly suggest that MTX-activated Ca²⁺ channels in spermatogenic cells can be regulated by a Ca²⁺-CaM-dependent protein kinase.