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Mouse sperm K currents stimulated by pH and cAMP possibly coded by Slo3 channels
Authors:Pablo Martínez-López  Claudia L Treviño  Juan J Acevedo  Lawrence B Salkoff
Institution:a Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), 62210 Cuernavaca, Morelos, Mexico
b Department of Anatomy and Neurobiology, Washington University School of Medicine, Saint Louis, MO, USA
c Departamento de Fisiología y Farmacología, Facultad de Medicina, Universidad Autónoma del Estado de Morelos, Cuernavaca, Mexico
d Department of Cell Biology and Physiology, Washington University, Saint Louis MO WA
Abstract:Slo3 channels belong to the high conductance Slo K+ channel family. They are activated by voltage and intracellular alkalinization, and have a K+/Na+ permeability ratio (PK/PNa) of only approximately 5. Slo3 channels have only been found in mammalian sperm. Here we show that Slo3 channels expressed in Xenopus oocytes are also stimulated by elevated cAMP levels through PKA dependent phosphorylation. Capacitation, a maturational process required by mammalian sperm to enable them to fertilize eggs, involves intracellular alkalinization and an increase in cAMP. Our mouse sperm patch clamp recordings have revealed a K+ current that is time and voltage dependent, is activated by intracellular alkalinization, has a PK/PNa ? 5, is weakly blocked by TEA and is very sensitive to Ba2+. This current is also stimulated by cAMP. All of these properties match those displayed by heterologously expressed Slo3 channels, suggesting that the native current we observe in sperm is indeed carried by Slo3 channels.
Keywords:Slo3 channels  Sperm  Capacitation  Potassium currents  cAMP  pH regulation  Slo channels
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