[Analysis of the mechanisms determining the varying relationship of the sperm from the marine and freshwater forms of the three-spined stickleback to the salinity of the medium].
The causes of differences in the reaction of spermatozoa of the fresh-water (morpha leiurus) and marine (m. trachurus) forms of three-spined stickleback Gasterosteus aculeatus to the high sea water salinity (the upper limit of spermatozoan motility being 18% and 52%, resp.) were investigated. The experiments with solutions of pure NaCl, CaCl2, MgCl2, KCl, LiCl (25 g/l) have shown that the movement of spermatozoa of m. leiurus is inhibited by NaCl only. The inhibition of chlorine channels of the plasma membrane by a specific inhibitor furosemide has shown that the activity of spermatozoa of m. leiurus is suppressed by the high Na+ concentrations. The experiments with ATP have revealed no differences in the activity of Na pump between the spermatozoa of mm. trachurus and leiurus. Amyloride, an inhibitor of Na channels, at a concentration of 1.10(-5) M relieved the inhibiting effect of the high Na+ concentrations on the activity of spermatozoa of m. leiurus. The differences in the reaction of spermatozoa of two forms of the stickleback appear, to be determined by differences in Na channels of the plasma membrane.