Effect of steroid hormones and capacitation on membrane potential of human spermatozoa.
The accumulation of the lipophilic cation radiolabeled triphenylmethylphosphonium (TPMP+) was utilized to determine the resting membrane potential across the plasma membrane (psi) on human sperm. Washed sperm were suspended and incubated in low-K+ and high-K+ medium and allowed to take up the cation to a steady state (that is, 20 min at 37 degrees C). The data were transformed according to concentration using the intracellular volume and with these values inserted in the Nernst equation we obtain psi. When the concentration of K+ was low in the medium, the psi was -69 +/- 2 mV, the psi was temperature- and pH-dependent. The sperm were incubated in the same conditions in the presence of testosterone, estradiol, and progesterone. The addition of these hormones induced the decrease in psi by about 29%, 32%, and 40%, respectively. On the other hand, capacitation of spermatozoa was induced by the addition of calcium and the ionophore A23187 and in these conditions the psi decreased 50%. The action of the hormones on sperm membrane was accompanied by some steroid-dependent structural modification promoting the psi decrease. This effect plays an important role in the capacitation, preparing it for sperm penetration in the ova.
Calzada
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L
Unidad de Investigación Clínica en Enfermedades Endocrinas, Hospital de Gineco-Obstetricía No. 4, Mexico.
Bernal
A
A
Loustaunau
E
E
D012739:Gonadal Steroid Hormones / Q000502:physiology*; D006801:Humans; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009861:Onium Compounds / Q000493:pharmacokinetics; D013075:Sperm Capacitation / Q000187:drug effects*; D013094:Spermatozoa / Q000502:physiology*; D014320:Triphenylmethyl Compounds / Q000493:pharmacokinetics
D012739:Gonadal Steroid Hormones; D009861:Onium Compounds; D014320:Triphenylmethyl Compounds; C011561:triphenylmethylphosphonium