Leaky Calcium Channels May Cause Heart Failure

Heart researchers have found that an imbalance in calcium metabolism in the sarcoplasmic reticulum (SR) of cardiac muscle cells may be an underlying cause of progressive heart failure. The SR is an internal section of the cell membrane that is specially adapted for calcium ion storage and release. This process is mediated by voltage gated calcium channels, and the calcium ATPase that pumps calcium ions into the SR.

Investigators at Ohio State University (Columbus, USA) used microscopic fluorescence imaging techniques to study the behavior of ryanodine receptor (RyR) calcium channels in isolated cardiomyocytes. They also studied single RyR channels removed from heart cells and reconstituted into lipid bilayers.

Findings published in the September 19, 2005, online edition of the Proceedings of the [U.S.] National Academy of Sciences revealed that failure of the RyR receptors to close properly resulted in a calcium imbalance that caused the cardiomyocytes to gradually lose their ability to contract.

"We found some drastic changes in the way muscle cells in the failing heart handle calcium,” said senior author Dr. Sandor Gyorke, professor of physiology and cell biology at Ohio State University. "Discovery of this mechanism suggests at least one potential target for treating the causes of this disease in a rational manner.”




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