Rising tension. Fat cells produce compounds that cause high blood pressure, a study shows.
Obesity has reached proportions in the Western world, bringing with it a surge in hypertension. But why do people with extra fat suffer from high blood pressure has been elusive. The research reported in this week's issue of Proceedings of the National Academy of Sciences reveals how fat tissue makes his evil.
Scientists have long known that high blood pressure, which can lead to stroke and heart failure, is caused by the adrenal glands pumping out too much of a hormone called aldosterone. Recently, experiments have shown for the first time that adipocytes can produce types of signaling molecules that may stimulate the adrenal gland. In the current study, Monika Ehrhart-Bornstein, a cell biologist at the University of Düsseldorf, Germany, and colleagues isolated the soup of molecules secreted by adipocytes and tested whether they have stimulated the cells of the adrenal glands in vitro to produce more aldosterone.
The results were dramatic: adipocytes secretions caused a 7-fold jump in the production of aldosterone. To zero in on the causative agent, they tested different cell sizes of fat molecules. The fraction consisting of larger molecules accounted for 60% of sales, while smaller molecules had no activity on themselves. The addition of these small molecules back with the greatest reduced full activity, indicating that at least two compounds churned out by adipocytes act together to stimulate the adrenal gland. The culprits molecules have not yet been identified. However, the team was able to rule on a well known adrenal-stimulating molecule called angiotensin II, lending hope that the real culprits are unknown hormones. This could open the door to new treatments for hypertension.
"The work is very important," says Julio Licinio, an endocrinologist at the University of California, Los Angeles, because it "links to the biology of two important human diseases. "Licinio added that" it would be very nice to know the structures and the genes encoding these new factors. "
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