Obesity Plus High Salt Diet Equal Deadly Combination for Heart and Kidneys
Separately, excess body weight and high dietary sodium intake are two important individual risk factors in the development of hypertension (high blood pressure). However, research scientists in Tokyo have discovered a biological mechanism that when obesity and sodium are combined together, a dangerous cellular process occurs that cause more damage to the heart and kidneys than when each condition is considered alone.
In Obese, Salt-Sensitive Individuals, Diet May Trigger More Dangerous Biological Mechanism
Toshiro Fujita MD, a professor and chairman of the Department of Internal Medicine and chief of the Department of Nephrology and Endocrinology at the University of Tokyo, studied the effect of a cellular protein called RAC1 in laboratory rats. The Ras-related C3 botulinum toxin substrate 1 protein contributes to the regulation of many cellular events, including the control of cell growth and the activation of protein kinases.
When obese rats, bred to have a sensitivity to salt, were fed a high-sodium diet, the team found that Rac1 activated the mineralocorticoid receptor (MR) on the kidney cells, an area normally activated by the hormone aldosterone. The expression of the MR caused a cascade of processes that promote the reabsorption of salt, causing the body to retain fluid and leading to high blood pressure.
Having high blood pressure (140/90 or above) causes excess force against the walls of the arteries as the heart pumps blood throughout the body. This excess force can cause damage and lead to complications such as stroke, heart attack, heart failure, kidney disease, and early death. Sometimes there are no symptoms to hypertension, and some patients may develop complications without even knowing they have high blood pressure.
The study findings not only stress for individuals who are overweight to take better care of their lifestyle choices, such as eating a heart-healthy, low-calorie diet and increasing physical activity, but it also serves as an alternative target for pharmaceutical companies who are developing anti-hypertension drugs. When Rac1 inhibitors were administered to the rats in Dr. Fujita’s study, the team was successful in lowering the animals’ blood pressure. “Our data indicate that the Rac1-mediated pathway in the kidneys can be an alternative therapeutic target for salt-sensitive hypertension and salt-mediated kidney injury,” said Dr. Fujita.
According to the Centers for Disease Control and Prevention, 33% percent of American adults age 20 and older have high blood pressure. The latest statistics on obesity closely match this, with 33.8% of US adults having a BMI of 30 or above (the clinical measure of obesity).
“Aberant Rac1-MR Pathway in Salt-Sensitive Hypertension and Metabolic Syndrome,” presented at the 7th International Symposium on Aldosterone and the ENaC/Degenerin Family of Ion Channels, held September 18-22 in Pacific Grove, Calif. The conference is sponsored by the American Physiological Society.
PubMed Health, US National Library of Medicine, National Institutes of Health
Centers for Disease Control and Prevention
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