| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1 Department of Medicine and Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio 44106-4951; and 2 Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
The effect of thyroid hormone (T3) on the content of myocardial creatine (Cr), Cr phosphate (CrP), and high-energy adenine nucleotides and on cardiac function was examined. In the hearts of control and T3-treated rats perfused in vitro, while "low" and "high" contractile work was performed, T3 treatment resulted in a ~50% reduction in CrP, Cr, total Cr content (Cr + CrP), and in the CrP-to-Cr ratio. In addition, there was a slight fall in myocardial content of ATP and a large rise in calculated free ADP (fADP), resulting in a significant decrease in the ATP-to-fADP ratio in the hearts of hyperthyroid compared with euthyroid rats. Moreover, there was a substantial decrease in the level of ATP in hearts of T3-treated rats under high work conditions. Importantly, the ratio of cardiac work to oxygen consumption was not altered by thyroid status. Treatment with T3 also resulted in an almost threefold reduction in the content of Na+/Cr transporter mRNA in the ventricular myocardium and skeletal muscle but not in the brain. We conclude with the following: 1) changes in the expression of the Na+/Cr transporter mRNA correlate with Cr + CrP in the myocardium; 2) hearts of hyperthyroid rats contain lower levels of ATP and higher levels of fADP under both low and high work conditions but no reduction in efficiency of work output; and 3) the reduction in Cr and ATP in hearts of hyperthyroid rats may be the basis for the reduced maximal work capacity of the hyperthyroid heart.
free ADP; ATP; creatine phosphate; cardiac work output; creatine transporter mRNA
This article has been cited by other articles:
|
|
 |
|
  A. Halapas, P. Lembessis, I. Mourouzis, C. Pantos, D. V. Cokkinos, A. Sourla, and M. Koutsilieris Experimental hyperthyroidism increases expression of parathyroid hormone-related peptide and type-1 parathyroid hormone receptor in rat ventricular myocardium of the Langendorff ischaemia-reperfusion model Exp Physiol, February 1, 2008; 93(2): 237 - 246. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. A. Portman, K. Qian, J. Krueger, and X.-H. Ning Direct action of T3 on phosphorylation potential in the sheep heart in vivo Am J Physiol Heart Circ Physiol, May 1, 2005; 288(5): H2484 - H2490. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. C. Blunt, Y. Chen, J. D. Potter, and P. A. Hofmann Modest actomyosin energy conservation increases myocardial postischemic function Am J Physiol Heart Circ Physiol, March 1, 2005; 288(3): H1088 - H1096. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
