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31 P NMR studies of phosphate metabolism in the ovulatory process induced by gonadotropins in perfused rabbit ovary
Author(s) -
Tanaka Kunio,
Mizukami Akiyasu,
Kojima Naomi,
Ishikawa Mutsuo
Publication year - 1999
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/(sici)1099-1492(199906)12:4<249::aid-nbm554>3.0.co;2-y
Subject(s) - endocrinology , medicine , ovulation , ovary , human chorionic gonadotropin , perfusion , adenosine , adenosine triphosphate , adenosine monophosphate , gonadotropin , adenosine diphosphate , chemistry , metabolism , phosphorylation , biology , hormone , biochemistry , platelet , platelet aggregation
The concentrations of phosphate metabolites were measured in perfused rabbit ovaries before, during and after ischemia, and during the ovulatory process induced by the administration of pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (HCG) using 31 P NMR spectroscopy. A decrease in adenosine triphosphate (ATP) and an increase in inorganic phosphate (P i ) during ischemia were observed. After reperfusion of the ovary, both ATP and P i levels returned to their initial control levels. These results are in agreement with the results observed in other organ tissues. On the other hand, ATP levels rapidly decreased dose dependently with infusion of HCG during 10 h of perfusion. A decrease in ovarian ATP concentration after infusion of HCG was also confirmed by enzymatic analysis of the extracts from ovarian tissues. On the other hand, significant changes in P i levels were not observed throughout the perfusion period. Furthermore, significant changes in phosphomonoester (PME) levels, adenosine diphosphate (ADP) levels and intracellular pH were not observed before and during the infusion of HCG. The concentration of cyclic adenosine 3′,5′‐monophosphate (cAMP) in the perfusate after the perfusion was also measured during the ovulatory period. Within 30 min cAMP significantly increased dose dependently and reached peak levels within 60 min. The concentration of cAMP then gradually decreased. Ovulatory efficacy during the infusion of HCG was also observed. These results suggest that the decreased ATP in the successive processes leading to ovulation probably reflects protein phosphorylation through the activation of the cAMP‐dependent protein kinases prior to induction of various chemical reactions related to the initiation of ovulation. Copyright © 1999 John Wiley & Sons, Ltd.