Studies of metabolism of round spermatids: glucose as unfavorable substrate.

M. Nakamura, S. Okinaga, K. Arai

Research output: Contribution to journalArticle

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Abstract

The exposure of spermatids to glucose in the absence of pyruvate and lactate resulted in an extremely low energy charge. The adenosine 5'-triphosphate (ATP) level rapidly declined and the fructose 1,6-bisphosphate (FBP) and triose levels increased. These changes were prevented by the addition of pyruvate or lactate. The levels of ATP and FBP were inversely correlated. In cells exposed to glucose, FBP did not flow appreciably through the step of glyceraldehyde 3-phosphate dehydrogenase (GA3PDH). The lactate level did not change. However, when pyruvate or lactate was administered to cells exposed to glucose, the FBP level declined rapidly. This drop was accompanied by a commensurate increase in lactate. In these cells, pyruvate transport was suppressed, and the pyruvate taken up by these cells was mostly oxidized in the tricarboxylic acid (TCA) cycle without its being reduced to lactate. In this case, the ATP level increased, but to a level still lower than existed before exposure to glucose. Furthermore, when kinetic studies on the activity of 6-phosphofructokinase (PFK) were carried out, PFK appeared to be fully activated at intracellular levels of fructose 6-phosphate, ATP and adenosine 5'-monophosphate (AMP). These results indicate that the rate of glucose metabolism in glycolysis depends heavily on the energy charge. In cells exposed to glucose, the sugar does not flow appreciably through the glycolytic pathway due to inhibition of GA3PDH. Moreover, the ATP level cannot be recovered fully from the lowest level by the addition of pyruvate or lactate.(ABSTRACT TRUNCATED AT 250 WORDS)

Original languageEnglish
Pages (from-to)927-935
Number of pages9
JournalBiology of Reproduction
Volume35
Issue number4
Publication statusPublished - 1986 Nov
Externally publishedYes

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Spermatids
Pyruvic Acid
Lactic Acid
Glucose
Adenosine Triphosphate
Glyceraldehyde-3-Phosphate Dehydrogenases
Trioses
Phosphofructokinase-1
Phosphofructokinases
Citric Acid Cycle
Glycolysis
Adenosine Monophosphate
fructose-1,6-diphosphate

ASJC Scopus subject areas

  • Cell Biology
  • Developmental Biology
  • Embryology

Cite this

Studies of metabolism of round spermatids : glucose as unfavorable substrate. / Nakamura, M.; Okinaga, S.; Arai, K.

In: Biology of Reproduction, Vol. 35, No. 4, 11.1986, p. 927-935.

Research output: Contribution to journalArticle

Nakamura, M, Okinaga, S & Arai, K 1986, 'Studies of metabolism of round spermatids: glucose as unfavorable substrate.', Biology of Reproduction, vol. 35, no. 4, pp. 927-935.
Nakamura, M. ; Okinaga, S. ; Arai, K. / Studies of metabolism of round spermatids : glucose as unfavorable substrate. In: Biology of Reproduction. 1986 ; Vol. 35, No. 4. pp. 927-935.
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