Respiratory and phosphorylative activity of amphibian spermatozoa

Abstract

Bufo arenarum or Leptodactylus chaquensis spermatozoa have an endogenous respiration (Z(O2) = 1.4 to 4.2) that was not significantly enhanced by glucose or fructose. Succinate was oxidized by these spermatozoa at higher rates (Z(O2) = 5 to 14) while endogenous respiration was only slightly stimulated by glutamate or citrate. Both the endogenous and exogenous respiration were sensitive to respiratory chain inhibitors (rotenone, antimycin or cyanide). The respiration of frog and toad sperm was coupled to the synthesis of ATP. P/O ratios of 0.54 were determined in the presence of potassium fluoride and exogenous hexokinase. Oligomycin inhibited phosphorylation completely and respiration partially. The latter inhibition was released by uncouplers like dinitrophenol. It is concluded that frog and toad sperm have an active oxidative metabolism coupled to the synthesis of ATP.