Acetylcholine-Induced Calcium Movements in Hypotonically Washed Ram Spermatozoa

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Abstract
The uptake and release of 45Ca2+ by hypotonically washed ram spermatozoa has been investigated. The rate of 45Ca2+ uptake was reduced by 2,4-dinitrophenol (0.5 mM) and increased by acetylcholine (0.05 mM). The rate of efflux of 45Ca2+ into fresh nonradioactive medium from 45Ca2+ loaded spermatozoa was studied in the presence of various neurochemicals. Acetylcholine increased the rate of efflux and had a half maximal effect (K½) at ∼2 x 10-5 M. Eserine salicylate and d-tubocurarine also affected the rate of 45Ca2+ release; d-tubocurarine inhibited release (K½ = 2 x 10-4 M) and eserine salicylate stimulated release (K½ = 5 x 10-4 M). Potassium chloride (K½ = 1.7 mM) and calcium chloride (K½= 0.24 mM) also stimulated the rate of efflux of 45Ca2+.