Kinesiology & Applied Physiology
What are your general research interests?
In general, my research interest is in integrative cardiovascular physiology, more specifically understanding mechanisms of impaired vascular function and identifying interventions to improve vascular function.
What are your current projects and how are they funded? Who are your collaborators on these projects?
I am currently focusing on two areas of research. For the past several years, we have been studying vascular function in patients with chronic kidney disease. Patients with chronic kidney disease are at increased risk for cardiovascular disease, and impaired vascular function is thought to play a role. We are trying to determine the mechanisms of vascular impairment in kidney disease, which are important to understand for the development of interventions with the ultimate goal of reducing cardiovascular risk. These studies have been funded by the National Institute of Diabetes and Digestive and Kidney Diseases as well as the National Center for Research Resources. I collaborate with Dr. Ray Townsend at the University of Pennsylvania and Dr. Michael Stillabower from Christiana Care Health Services on these studies.
My other research focus is studying the vascular effects of dietary salt. Bill Farquhar and I recently received a grant from the National Heart, Lung, and Blood Institute to study the effects of high dietary salt intake in healthy individuals with normal blood pressure and whose blood pressure changes very little if at all when they alter their dietary salt intake. To date, our data are consistent with animal studies that suggest high dietary salt intake impairs vascular function independent of blood pressure. Typically the negative effects of salt are attributed to its effects on blood pressure, so these studies could result in a re-evaluation of the deleterious effects of salt. These studies are ongoing and involve collaboration with Dr. Shannon Lennon-Edwards from the Department of Behavioral Health and Nutrition at UD, Dr. Doug Seals from the University of Colorado, and Dr. Paul Sanders from the University of Alabama at Birmingham.
What are the likely “next steps” in your work?
We and others have identified oxidative stress as a general mechanism of vascular dysfunction in kidney disease, and we will continue this work by exploring the potential sources of reactive oxygen species in these patients. There are several candidate sources in the vasculature that we will examine. In addition, I have a grant proposal in review to examine the effects of aerobic exercise training on vascular function in kidney disease. Exercise is not routinely recommended to these patients, as it is for patients with cardiovascular disease or traditional cardiovascular risk factors, but it has great potential to improve vascular function and reduce cardiovascular risk in kidney disease.
There are two directions that our dietary salt studies can take. We will attempt to determine the mechanisms by which salt impairs vascular function using our current study design, which involves a 21-day controlled feeding study where we supply research study participants with 7 days each of low-, medium-, and high-salt foods. Although this will allow us to establish the deleterious vascular effect of salt and study mechanisms, ultimately we will need to move to dietary interventions to determine the role of long-term sodium restriction on vascular function in healthy individuals. Dr. Shannon Lennon-Edwards is also interested in examining the potential of dietary potassium to offset the negative effects of salt.
How would you describe your work’s importance to an interested lay audience?
Impaired vascular function is thought to be an important step in setting the stage for the development and progression of atherosclerosis. Therefore, understanding the reasons for impaired blood vessel function in kidney disease is very important. Similarly, it is also very important to understand the effect of dietary salt on blood vessel function.