Research Interests

Research in my lab focuses on renal and metabolic adaptations to perturbations such as hypertension and prolonged fasting, in either a natural or induced state. Questions regarding electrolyte and water regulation and natural prolonged food deprivation in a variety of animal models including seals and dolphins help us better understand the adaptations these animals have evolved to deal with these seemingly extreme conditions. Comparative species are viable models to address several of the pathophysiological conditions commonly seen in humans.

In addition, our lab is interested in the contributions of aldosterone and angiotensin II to the manifestation of hypertension, and renal and cardiovascular disease. We are also pursuing studies that address the link between diabetes and obesity with hypertension. The role of oxidative stress and inflammation in hypertension and diabetes is of research interest as well as the adaptive mechanisms evolved by seals to counter oxidative stress during prolonged fasting and diving- and sleep apnea-induced hypoxia.

The focus of my dissertation research was on the regulation of kidney function and the hormonal responses to fasting in northern elephant seal (Mirounga angustirostris) pups. After nursing for approximately one month, elephant seal pups are weaned, and fast for approximately 2.5 - 3 months on land before entering the water for the first time. Obviously, these animals have adapted to this life history strategy, but my interests lied with the physiological mechanisms that these animals employ to endure the extended fasting period.

One of the most important adaptations elephant seal pups have developed is reducing water loss by decreasing urine output, however the mechanisms involved with urine formation and excretion have not been well defined in this species. Another important adaptation that has allowed these animals to fast for such prolonged periods is a shift in metabolized substrate from protein within the first week to fat for the remainder of the fast. Periods of food restriction and fasting induce dramatic changes in a number of different hormones that help regulate a person's metabolic rate. However, an examination of these hormones in elephant seals is lacking. The intent of this research was to provide a much better understanding of the physiological mechanisms used to regulate kidney function and metabolism in a species adapted to prolonged periods of fasting, and to use this information to help elucidate the biomedical consequences of anorexia, diabetes, obesity, and renal dysfunctions in humans, as well.

Rudy M. Ortiz's Lab Group