Two-thirds of patients' high blood pressure remains beyond control inspite of the best efforts of doctors, according to a medical expert. "We are trying to identify the mechanisms through which blood pressure is regulated under normal everyday conditions - which is what stress is - and take that information back to the clinic to better determine what sort of therapy is going to be most effective at treating your blood pressure," said Gregory Harshfield, a director at Georgia Medical College (GMC). More than a dozen researchers have teamed up to do parallel studies in animal models and young adults to learn more about what factors like genes, stress and obesity contribute to BP and ways to control this. "This research will give us information that allows us to identify what treatment is going to be effective in what individual by genotype, by obesity and other factors. What kind of treatment is going to be effective at keeping an individual's blood pressure down or maybe preventing it from ever getting high," said Harshfield, principal investigator of the project funded by National Institutes of Health's National Heart, Lung and Blood Institute. Some 72 million Americans are hypertensive, according to the institute. Studies will explore fundamentals such as why about 30 percent of young healthy blacks and 15 percent of whites can't effectively excrete sodium, a problem that raises blood pressure by increasing the body's fluid volume. "We think there is a defect in their kidneys, in the normal mechanisms that allow them to excrete salt," said David Pollock, renal physiologist at GMC. "When blood pressure goes up due to stress, their kidneys ought to get rid of more salt so their blood pressure will come down, and they don't."