Creatine kinase function in mitochondria isolated from gravid and non-gravid guinea-pig uteri.
Mitochondria from gravid and non-gravid guinea pig uteri were isolated and respiratory rates examined to determine the responses to ATP, ADP and creatine. It was found that mitochondria isolated from gravid uterus had (i) a markedly higher respiration rate in state 3; (ii) a greater activation of respiration by creatine in the presence of 0.1 mM ATP and (iii) an elevated specific activity of mitochondrial creatine kinase. It was shown by a competitive enzyme method, using pyruvate kinase to trap ADP, that despite the presence of creatine kinase in the mitochondria, there is no functional coupling between mitochondrial creatine kinase and oxidative phosphorylation as has been shown for striated muscle. It is suggested that the function of uterine Mi-CK is to favour high energy phosphate turnover in conditions of increased metabolic demand in gestating uterine smooth muscle.
Department of Biochemistry, University of Oxford, UK.
J F
JF
Clark
A V
AV
Kuznetsov
Z
Z
Khuchua
V
V
Veksler
R
R
Ventura-Clapier
V
V
Saks
D000244:Adenosine Diphosphate / Q000378:metabolism / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001667:Binding, Competitive; D003401:Creatine / Q000494:pharmacology; D003402:Creatine Kinase / Q000378:metabolism*; D005260:Female; D006168:Guinea Pigs; D007527:Isoenzymes; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology*; D010085:Oxidative Phosphorylation; D010101:Oxygen Consumption / Q000187:drug effects; D010728:Phosphoenolpyruvate / Q000494:pharmacology; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D011770:Pyruvate Kinase / Q000378:metabolism / Q000494:pharmacology; D012503:Saponins / Q000494:pharmacology; D014599:Uterus / Q000201:enzymology / Q000648:ultrastructure*
D007527:Isoenzymes; D012503:Saponins; D000244:Adenosine Diphosphate; D010728:Phosphoenolpyruvate; D000255:Adenosine Triphosphate; D011770:Pyruvate Kinase; D003402:Creatine Kinase; D003401:Creatine