The findings, published in the January 18 issue of the Proceedings of the National Academy of Sciences, confirm what many scientists have conjectured for years about heart failure, and suggest new treatments designed to reduce energy demand and/or augment energy transfer.
"The heart consumes more energy per gram than any other organ," notes Paul A. Bottomley, Ph.D., lead researcher and director of magnetic resonance research at the Johns Hopkins Department of Radiology. "While scientists have long known that nucleotide adenosine triphosphate (ATP) is the chemical that fuels heart contractions and that creatine kinase (CK) is the enzyme for one of the sources of ATP, we believe this is the first time someone has actually measured the flux of ATP produced by CK reaction in the beating human heart."
Specifically, Bottomley and a team of cardiologists and radiologists at Hopkins used MRS to provide direct molecular-level measurements of the CK supply in normal, stressed and failing human hearts. Other team members include Robert G. Weiss, M.D., and Gary Gerstenblith, M.D., both in the Cardiology Division of the Hopkins Department of Medicine.
For the study, the researchers used an MRI device that combines conventional magnetic resonance imaging with spectroscopy to provide not only images of the anatomy, but also direct measurements of the concentrations of various important biochemicals and their chemical reaction rates within the cells of various tissues. They first performed MRS on 14 healthy volunteers to measure cardiac CK flux at rest and with pharmaceutically induced stress to determine whether increased energy demand during stress increases the rate of ATP synthesis through CK.
Then, 17 patients with histor
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Contact: Gary Stephenson
gstephenson@jhmi.edu
410-955-5384
Johns Hopkins Medical Institutions
3-Feb-2005