As an anesthesiologist, John H. Eisenach, M.D., is fascinated by how people respond so differently to blood pressure medications that are administered daily in operating rooms and intensive care units. He's also interested in how job strain and mental stress can predict the future development of hypertension in some individuals, but not others.
A major mechanism for how blood pressure is regulated is through a heart and blood vessel receptor called the beta-adrenergic receptor. Dr. Eisenach conducts research into how genetic variation in beta-adrenergic receptors influences blood pressure regulation in humans.
- Beta-adrenergic receptor gene variation. During his anesthesia residency at Mayo Clinic, Dr. Eisenach began conducting research in the Mayo Clinic Human Integrative Physiology Laboratory. Upon joining Mayo Clinic's staff, he received a five-year mentored patient-oriented career development award grant (K23) from the National Institutes of Health (NIH).
In studies performed under that award, Dr. Eisenach discovered that small variations (polymorphisms) in the gene encoding the beta-2 adrenergic receptor alter heart and blood vessel responsiveness to pharmacologic and physiologic stimulation, and that dietary salt restriction modulates these genetic influences.
This work allowed Dr. Eisenach to obtain a five-year R01 grant from NIH. To study beta-2 adrenergic receptor gene variation, his laboratory performed detailed and mechanistic human physiology studies to define the relationship between the blood pressure response to stress maneuvers such as mental stress and handgrip, and determine whether dietary sodium manipulation affects the blood pressure responses based on genotype.
- Blood vessel function. While studying beta-2 adrenergic receptor gene variation through his R01 grant, Dr. Eisenach found that depending on dietary sodium, blood vessel function is different in young men compared with young women. Blood vessel function in healthy young men appears to respond to high- and low-sodium diets, but blood vessel function in healthy young women appears to be resistant to high- and low-sodium diets.
With these findings, Dr. Eisenach is applying for a five-year renewal of this NIH R01 grant, which will enable him to compare how dietary salt affects heart and blood vessel function in men and women as they age, particularly for postmenopausal women.
These proposals are consistent with the NIH Roadmap for Medical Research and Mayo's NIH Clinical and Translational Science Award.
Significance to patient care
A major problem in the U.S. is high salt intake, which leads to an increased prevalence of hypertension and heart disease. While major health initiatives such as the DASH diet recommend decreased salt intake, it is unclear why blood pressure is sensitive to salt reduction in some people but resistant to salt reduction in others.
Dr. Eisenach's studies will lead to a better understanding of the mechanisms that cause women to have an accelerated risk of high blood pressure and cardiovascular disease after menopause compared with young women. His studies will also improve our understanding of how dietary salt intake affects blood vessel function in men versus women, earlier and later in adulthood.
- Continuous research funding from the National Institutes of Health, 2002-present
- President, Mayo Foundation Chapter, Sigma Xi, The Scientific Research Society, 2009
- Presidential Scholar Award (for an outstanding early career in anesthesiology practice and research), American Society of Anesthesiologists, 2008
- GCRC Outstanding Trainee Award, GCRC Plenary Session, Clinical Research, Washington D.C., 2005
- Richard A. Theye Award for Clinical Anesthesia Residency Research, Department of Anesthesiology, Mayo Clinic, 2002