1. POTASSIUM INCREASES INTRACELLULAR CALCIUM SIMULATING PROGESTERONE ACTION IN HUMAN SPERM
- Author
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Ying Yk, Kumar S, Hong P, and Maddaiah Vt
- Subjects
Male ,endocrine system ,medicine.medical_specialty ,Fura-2 ,Acrosome reaction ,chemistry.chemical_element ,In Vitro Techniques ,Calcium ,Biology ,Calcium in biology ,chemistry.chemical_compound ,Endocrinology ,Internal medicine ,medicine ,Humans ,Acrosome ,Zona pellucida ,Progesterone ,Zona Pellucida ,reproductive and urinary physiology ,urogenital system ,Calcium Channel Blockers ,Spermatozoa ,Sperm ,EGTA ,medicine.anatomical_structure ,chemistry ,Potassium ,Calcium Channels ,Sperm Capacitation - Abstract
Progesterone (P) and zona pellucida are known to induce acrosome reaction in human sperm by increasing cytosolic calcium. High concentrations of potassium ions (K+) improve the rate of acrosome reaction in human sperm in vitro. This article determined whether the effect of K+ on the acrosome in human sperm is mediated by increasing intracellular calcium ([Ca2+]i). The effect of K+ on [Ca2+]i was examined by using Fura 2 as the fluorescent indicator. The effect of K+ and P on [Ca2+]i in sperm and the involvement of ion channels was compared. Motile sperm were collected by the swim-up method from semen of healthy volunteers and capacitated overnight in BWW containing 0.5% BSA. Incubation of capacitated sperm with different concentrations of potassium chloride (1.25-20 mM) resulted in dose-dependent increase in [Ca2+]i similar to that observed with P. The increase in [Ca2+]i by K+ and P was blocked by the addition of EGTA, a Ca2+ chelator. K+-induced change in [Ca2+] was not altered by the addition of dihydropyridine derivatives. The combined treatment of K+ (20 mM) and P (0.75 microg/mL) caused an additive effect on the increase in [Ca2+]i. It would appear that human sperm plasma membrane possess different Ca2+ channels responsive to P and K+.
- Published
- 2000
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