AJP - Endocrinology and Metabolism, Vol 253, Issue 4 E391-E394, Copyright © 1987 by American Physiological Society
Absence of detectable phosphocreatine in rat luteal cells
J. C. Cross, L. K. Soodak, B. Musicki and H. R. Behrman
Department of Obstetrics and Gynecology, Yale University School of Medicine, New Haven, Connecticut 06510.
Previous studies from this laboratory showed that adenosine amplifies the
action of luteinizing hormone (LH) severalfold in rat and human luteal
cells by an intracellular, adenosine 5'-triphosphate (ATP)-linked process.
The objective of this study was to evaluate the contribution of
phosphocreatine (PCr) and creatine kinase (CK) to the dynamics of luteal
ATP metabolism. Levels of PCr in luteinized rat ovaries were similar to
those seen in liver but were approximately 1 and 7% of levels found in
skeletal and heart muscle, respectively. In isolated rat luteal cells,
little detectable PCr was seen after incubation in the presence or absence
of adenosine, although cell ATP levels were increased twofold by adenosine
treatment. The presence or absence of LH had no effect on either PCr or ATP
levels in incubations of isolated luteal cells. Analysis of CK activity in
tissue and cell homogenates showed that the specific activity of CK in
luteal cells was in the same range as that seen in liver but less than 1/30
of that seen in skeletal muscle. From these studies we conclude that rat
luteal cells contain little, if any, PCr and low levels of CK. Thus the
rapid changes in ATP levels that are seen in rat luteal tissue and cells
may occur because these cells have little capacity to buffer ATP levels
with a reservoir of high-energy phosphate groups in the form of PCr.
