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5 December 2013 11:26 am ,
Vol. 342 ,
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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1 May 1997 (All day)
Researchers have found that a high-salt diet triggers subtle biochemical changes that can fatally throw off the heart's rhythm in rats with high blood pressure. The findings, reported in tomorrow's issue of Science,* suggest how untreated hypertension in people can lead to chronic heart failure.
Physicians have long thought that in a hypertensive person, the heart adapts to the stress by enlarging to pump blood more efficiently. Thinking such swelling may not be so benign, W. Jonathan Lederer and colleagues at the University of Maryland School of Medicine in Baltimore probed the mechanism by which heart muscle cells absorb calcium, which causes the heart to contract. They fed a high-salt diet to a strain of rats bred to have high blood pressure, and analyzed changes in the way calcium moves into a cell to trigger a contraction.
The researchers found that the gaps between the calcium channels and calcium receptors located just inside the cellular membrane had widened. At first, however, the rats overcame this defect by producing extra adrenaline that heightened the receptors' sensitivity to calcium. But after several weeks of steady enlargement, the damaged hearts began to contract poorly, resulting in heart failure.
Experts are impressed with the study. "What's surprising is that most of the problems seem to be in the one step between the electrical excitation of the heart and its contraction," says David Yue, a biomedical engineer at Johns Hopkins University School of Medicine in Baltimore. Such a fundamental, fatal process is likely also to occur in people, Lederer says. The message for those with high blood pressure, he says, is "Don't wait to treat it, because you're developing an irreversible defect." In the meantime, Lederer says, drug companies should aim to test agents that heighten the sensitivity of calcium receptors in hypertensive people.