Physiological Reviews, Vol. 79, No. 2, April 1999, pp. 481-510
Copyright ©1999 by the American Physiological Society
Ion Channels in Sperm Physiology
Alberto
Darszon,
Pedro
Labarca,
Takuya
Nishigaki, and
Felipe
Espinosa
Departamento de Genética y Fisiología Molecular,
Instituto de Biotecnología, Universidad Nacional Autónoma
de México, Morelos, Mexico; and Centro de Estudios
Científicos de Santiago and Facultad de Ciencias, Universidad
de Chile, Santiago, Chile
Darszon, Alberto,
Pedro Labarca,
Takuya Nishigaki, and
Felipe Espinosa.
Fertilization is a matter of life or
death. In animals of sexual reproduction, the appropriate communication
between mature and competent male and female gametes determines the
generation of a new individual. Ion channels are key elements in the
dialogue between sperm, its environment, and the egg. Components from
the outer layer of the egg induce ion permeability changes in sperm that regulate sperm motility, chemotaxis, and the acrosome reaction. Sperm are tiny differentiated terminal cells unable to synthesize protein and difficult to study electrophysiologically. Thus
understanding how sperm ion channels participate in fertilization
requires combining planar bilayer techniques, in vivo measurements of
membrane potential, intracellular Ca2+ and intracellular pH
using fluorescent probes, patch-clamp recordings, and molecular
cloning and heterologous expression. Spermatogenic cells are larger
than sperm and synthesize the ion channels that will end up in mature
sperm. Correlating the presence and cellular distribution of various
ion channels with their functional status at different stages of
spermatogenesis is contributing to understand their participation in
differentiation and in sperm physiology. The multi-faceted approach
being used to unravel sperm ion channel function and regulation is
yielding valuable information about the finely orchestrated events that
lead to sperm activation, induction of the acrosome reaction, and in
the end to the miracle of life.
