Role of Calcium and Calcium Channels in Progesterone Induced Acrosome Reaction in Caprine Spermatozoa

Autor: K. K. Gandhi, P. R. Somanath
Rok vydání: 2002
Předmět:
Zdroj: Asian-Australasian Journal of Animal Sciences. 15:949-956
ISSN: 1976-5517
1011-2367
DOI: 10.5713/ajas.2002.949
Popis: There are several physiological and pharmacological evidences indicating that opening of voltage dependent Ca 2+ channels play a critical role in induction of acrosome reaction in mammalian sperm. We determined the intracellular free Ca 2+ concentration in ejaculated goat sperm using a fluorescent, Ca 2+ -specific probe, Fura2/AM, after the suspension of sperm in KRB medium, capable of sustaining capacitation and the acrosome reaction. We used nifedipine, D-600 and diltiazem, the Ca 2+ channel antagonists belonging to the classes of dihydropyridines, phenylalkylamines and benzothiazepines, to investigate the possibility that L-type voltage gated Ca 2+ channels play a role in the progesterone-stimulated exocytotic response. Progesterone promoted a rise in intracellular Ca 2+ in goat sperm and addition of nifedipine (100 nM) just prior to progesterone induction, significantly inhibited both intracellular Ca 2+ rise and exocytosis suggesting that Ca 2+ channels are involved in the process. However, the intracellular Ca 2+ increase during the process of capacitation was not affected with the addition of nifedipine suggesting a role of focal channel for Ca 2+ during capacitation. Studies using monensin and nigericin, two monovalent cation ionophores showed that an influx of Na + also may play a role in the opening of Ca 2+ channels. These results strongly suggests that the entry of Ca 2+ channels with characteristics similar to those of L-type, voltage-sensitive Ca 2+ channels found in cardiac and skeletal muscle, is a crucial step in the sequence of events leading to progesterone induced acrosome reaction in goat sperm. (Asian-Aust. J. Anim. Sci. 2002. Vol 15, No. 7 : 949-956)
Databáze: OpenAIRE
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