The University of Alabama at Birmingham has been selected as a recipient of a highly competitive American Heart Association (AHA) Strategically Focused Hypertension Center, encompassing population, clinical, and basic research projects, as well as a training component. The UAB Hypertension Center is concentrated on studying diurnal blood pressure patterns, salt sensitivity, and cardiovascular (CVD) risk. Dr. Paul Muntner, professor and vice chair in UAB’s department of epidemiology, is the center principal investigator (PI) and population project PI; Dr. David Calhoun, professor in the division of cardiovascular disease and medical director of the Vascular Biology & Hypertension Program, is the clinical project PI; and Dr. Jennifer Pollock, professor in the division of nephrology, is the basic science project PI. Additionally, the center has a partnership with investigators at Columbia University, led by Dr. Daichi Shimbo.
The center program is designed to change how hypertension is diagnosed and then treated in the United States. Blood pressure is typically measured in a doctor’s office, which does not identify patients who have high blood pressure outside of that setting; conversely, ambulatory blood pressure monitoring allows blood pressure to be measured over a 24-hour period. This is of particular interest since recent studies from Europe and Asia have shown that many people have high blood pressure when they are asleep. These studies also found high blood pressure at night to be associated with an increased risk for cardiovascular disease and mortality independent of clinic-measured blood pressure. As ambulatory blood pressure monitoring is currently not routinely used in the United States, many individuals with high blood pressure at night may not be diagnosed.
Therefore, the researchers seek to determine the percentage of middle-aged U.S. adults with hypertension at night and with blood pressure that does not decline between daytime and nighttime. They will also establish whether these occurrences are associated with cardiovascular and kidney disease,as well as provide policy information by determining whether it is cost-effective to diagnose and treat hypertension using ambulatory blood pressure monitoring. With a major question to be addressed being how salt sensitivity is linked to increased blood pressure during the night, Dr. Calhoun and his colleagues will be conducting a randomized controlled trial to determine if a high-salt diet increases nighttime blood pressure by worsening sleep apnea. Dr. Pollock will determine whether a high-salt diet increases the production of reactive oxygen species that mediate dysfunction in small arteries of the kidney that are critical for maintaining blood pressure. In addition, Dr. Pollock’s team will also examine whether genes that regulate circadian control are not regulating the small arteries function in the salt-sensitive rat model. Drs. Pollock and Calhoun will also measure the circadian control genes in humans on high- or low-salt diets, as well as blood pressure throughout the day and night. The center has a training component that will allow three post-doctoral fellows to gain experience in population, clinical, and basic science research related to hypertension.
By appropriately diagnosing and treating high blood pressure, this study is poised to help the AHA achieve its goal of reducing cardiovascular disease by 20 percent.