Understanding the mechanisms of blood pressure regulation has been the focus of my research career.  My research has incorporated an integrated physiology approach to understanding how multiple organ systems contribute to the regulation of blood pressure.  During my academic career, I studied the pathology of hypertension, and how organ systems respond differently between males and females.  I have investigated how the neural, endocrine, renal and cardiovascular systems respond to hypertensive stimuli to elicit an integrated effect on blood pressure in male and female rats.  The rodent models of experimental hypertension which I have studied are spontaneously hypertensive rats, one-kidney-one wrap Grollman model, partial nephrectomy model, deoxycorticosterone acetate (DOCA)-salt model, and Dahl salt sensitive rats.  In my studies, I have recorded blood pressure and heart rate in conscious rats by chronic indwelling catheters or by radiotelemetry to determine the short-term and long-term effects of drug treatment, salt diet, sex hormone (estrogen) depletion or replacement, and aging.  I have assessed the contribution of the sympathetic nervous system by recording renal sympathetic nerve activity, measuring circulating catecholamines, and by various pharmacological techniques to assess baroreflex function.  The contribution of the renin-angiotension, vasopressin, and endothelin systems has been assessed by measuring circulating levels of various components of these endocrine systems, and by pharmacologically blocking or stimulating angiotensin, vasopressin, or endothelin receptors. Using rodent metabolic cages, I have evaluated water and electrolyte homeostasis by measuring water intake, urine output, sodium/potassium intake and excretion, and glomerular filtration rate.   

During my career as a research physiologist for the US Army, I continue to use an integrative physiology approach to study blood pressure regulation during hemorrhage.  I have used lower body negative pressure (LBNP) as an experimental model of hemorrhage to evaluate the compensatory responses to hypovolemia in conscious human volunteers. We monitor blood pressure, heart rate, respiration, cerebral blood velocity, and muscle sympathetic nerve activity during LBNP and use this information to develop sophisticated medical monitors embedded with machine learning algorithms that are able to assess blood volume status and predict the course of hemorrhage in a trauma patient.  Currently, my research focuses on the effect of pre-hospital pain control on the compensatory responses to hemorrhage.  On the battlefield, traumatic injury is usually associated with blood loss which elicits cardiovascular compensatory responses to maintain hemodynamic stability.  Pain control on the battlefield may suppress these compensatory responses. These studies will help define best practices and innovative alternatives to current medical guidelines for pre-hospital care.