TEMPERATURE ADAPTATION CHANGES ION CONCENTRATIONS IN SPERMATOZOA AND SEMINAL PLASMA OF COMMON CARP WITHOUT AFFECTING SPERM MOTILITY

Cold or warm adaptation usually results in changes of the cellular par ameters of poikilothermic animals. However, no data are available abou t the changes in cellular parameters of sperm samples from cold or war m adapted animals. Here the effects of warm and cold adaptation on the spermation of common carp (Cyprinus carpio L,) and the changes in the characteristics of the individual sperm cells are described. Measurem ents were carried out on semen samples from 10 warm adapted and 10 col d adapted animals. The sperm cells from the cold adapted animals had a higher intracellular pH (7.4 +/- 0.1) than those from the warm adapte d ones (7.1 +/- 0.1). The pH of the seminal plasma of the cold adapted animals (8.6 +/- 0.2) was also higher than that of the warm adapted a nimals (8.3 +/- 0.1). The concentration of spermatozoa in the semen of cold adapted animals was about half that for the warm adapted animals (0.7 +/- 0.1 X 10(10) vs. 1.4 +/- 0.2 X 10(10) cells/ml). The Na+ con centration of the seminal plasma of the cold adapted animals (83 +/- 1 2 mM) was higher, while the K+ concentration in these samples (64 +/- 11 mM) was lower than the corresponding data for the warm adapted anim als (63 +/- 10 mM and 87 +/- 16 mM, respectively). All of these differ ences proved to be significant at 5% level of significance using the S tudent's t-test, In contrast, there was no significant difference betw een the intracellular free K+ concentrations in the spermatozoa from c old and warm adapted animals (58 +/- 8 mM vs. 60 +/- 7 mM), The ion co mpositions and concentrations of the blood sera of cold and warm adapt ed animals were similar. Also, the motile fraction and duration of mot ility of the spermatozoa from cold and warm adapted animals were ident ical. An increase by 0.2 pH unit occurred in the intracellular pH duri ng hypoosmotic shock induced motility of sperm cells from the cold and warm adapted animals. This pH increase could be blocked by the Na+/H exchange inhibitor amiloride in a concentration of 100 mu M. Based on the kinetics of the processes involved and on additional experimental evidence it is suggested that the hypoasmotic shock induced immediate hyperpolarization of the sperm under usual spawning conditions. Thus, it may be a regulatory step in the motility activation of common carp sperm but not in the relatively slowly occurring intracellular alkali nization. (C) 1998 Published by Elsevier Science B.V. All rights reser ved.