Role of sodium bicarbonate on the initiation of sperm motility in the Japanese eel

S. Tanaka, T. Utoh, Y. Yamada, N. Horie, A. Okamura, A. Akazawa, N. Mikawa, H.P. Oka, H. Kurokura-2004

Fisheries Science, 70(5): 780-787 

Abstract:

In order to find out the role of sodium bicarbonate (NaHCO₃) on the initiation of sperm motility in the Japanese eel Anguilla japonica, interactions were investigated between NaHCO₃ and various reagents (K⁺ channel blocker 4-aminopyridine [4-AP], ammonium chloride [NH₄Cl], sodium acetate and calcium chloride [CaCl₂]) that could regulate internal factors (intracellular K⁺, intracellular pH [[pH]_i] and intracellular Ca²⁺) in sperm motility. Contradictory effects of NaHCO₃ were observed (i.e. an inhibitory effect when 4-AP was absent and a promoting effect when 4-AP was present). Sodium bicarbonate inhibited the initiation of sperm motility in the Japanese eel. However, NaHCO₃ restored the motility of immotile sperm that 4-AP inhibited. The inhibitory effect of NaHCO₃ disappeared with the addition of NH₄Cl, which raised [pH]_i, but the promoting effect was not affected by [pH]_i. Although NaHCO₃ recovered motility in the presence of 4-AP, this recovery was also observed with the addition of CaCl₂ instead of NaHCO₃. In the initiation of sperm motility in the Japanese eel, two roles for NaHCO₃ are suggested: an inhibitory role relating to the regulation of [pH]_i and a promoting role relating to the uptake of another initiation factor, which could be Ca²⁺.

(IRAGO Institute, Atsumi, Aichi 441-3605, Japan, Email: tanaka@irago.co.jp)

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