Calcium Modulator Protects Heart from Stress

A protein called Kir6.2 has been shown to enable the heart to react to stress without damage to the organ by helping to modulate the flow of calcium into heart cells. This finding was reported in the October 1, 2002, issue of the Proceedings of the National Academy of Sciences.

Investigators from the Mayo Clinic (Rochester, MN, USA) worked with a mouse strain that had been genetically engineered to lack the gene for production of Kir6.2. They found that mice lacking this protein had reduced cardiac tolerance for both exercise- and adrenaline-like stress. Nearly three-quarters (73%) of the Kir6.2-deficient mice died within 14 minutes of a stress test while all the mice that possessed Kir6.2 survived.

Heart cells in the mice lacking Kir6.2 were found to be overloaded with calcium, and this damaged cell structure. Administering calcium-channel blockers, a common heart medication, to those Kir6.2-deficient mice prevented the fatal arrhythmias in five out of six animals.

"We have identified in the heart a protective mechanism against stress that is roughly analogous to an automatic sprinkler system that douses a fire in an emergency,” explained senior author Dr. Andre Terzic. "The Kir6.2 protein senses stress and prevents damage to the heart by helping the cells maintain equilibrium even under peak workloads. Lack of Kir6.2 protein function causes sudden, irreversible damage to heart cells, which could lead to heart failure.”





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