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Metabolism of Round Spermatids: Pyruvate cannot Maintain the ATP Level
Author(s) -
NAKAMURA MASAHISA,
KAMACHI TERUYUKI,
OKINAGA SHOICHI,
ARAI KIYOSHI
Publication year - 1986
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1111/j.1440-169x.1986.00489.x
Subject(s) - pyruvate decarboxylation , pyruvate dehydrogenase complex , pyruvate dehydrogenase kinase , pyruvate dehydrogenase phosphatase , nad+ kinase , oxidative phosphorylation , biochemistry , intracellular , dihydrolipoyl transacetylase , lactate dehydrogenase , glycolysis , substrate (aquarium) , chemistry , metabolism , biology , enzyme , ecology
Round spermatids (steps 1–8) were isolated from rat testes and the effect of pyruvate on their intracellular ATP level was examined. Results showed that although the spermatids consumed a considerable amounts of pyruvate, this substrate alone did not maintain their ATP level. However, their ATP level was maintained in the presence of both pyruvate and α‐ketovalerate or α‐ketobutyrate. Maintenance of the ATP level by these substrates was associated with electron trasnport and oxidative phosphorylation. α‐Ketoacid inhibited pyruvate reduction to lactate in the lactate dehydrogenase (LDH) reaction, but increased pyruvate oxidation to CO 2 . The NADH level in spermatids was too low to be detectable, but the NAD level remained unchanged in the presence of pyruvate and α‐ketovalerate. These results suggest that pyruvate by itself is not an adequate energy‐yielding substrate for spermatids and that a high NADH/NAD ratio may be essential for maintenance of their ATP level.