John Osborn
University of Minnesota
Professor
Marvin and Hadassah Bacaner Chair of Cardiovascular Physiology
Department of Integrative Biology and Physiology
Education and Training
B.S., Physiology, Michigan State University, 1981
Ph.D., Physiology, Medical College of Wisconsin, 1986
Post Doc, Biomedical Engineering, Johns Hopkins School of Medicine
Overview of the role of the Osborn Laboratory in the NCDC
According to our Central Hypothesis, angiotensin II administered over long periods of time will activate the sympathetic nervous system resulting in hypertension. My laboratory is investigating mechanisms whereby acute and chronic changes in sympathetic nerve activity alter regional and systemic hemodynamic function in conscious rats. We propose that angiotensin II stimulates sympathetic activity is in organ specific manner (i.e. differentially) rather than in an “all or none fashion”. We employ a number of techniques to address these issues.
Measurement of regional hemodynamic function
In order to determine the role of different vascular beds (i.e., renal, splanchnic, skeletal muscle) in the development of AngII-salt hypertension, we are also measuring regional blood flow and arterial pressure continuously in chronically instrumented rats. In this example, a Transonic flow probe was implanted on the left renal artery to continuously measure renal blood flow over an 80 day period (Panel A). Panel B shows the acute response of mean arterial pressure (MAP), renal blood flow (RBF) and renal vascular resistance (RVR) to the vasoconstrictor phenylephrine (PE) and the vasodilator
nitroprusside (NP) on days 54, 55, 59 and 80 after instrumentation.
Long-term measurement of sympathetic nerve activity in conscious rats
The most technically challenging aspect of research in this area is direct measurement of sympathetic nerve activity in conscious animals over long periods of time. Dr. Kenju Miki of Nara Womens University in Nara Japan has recently developed this method for long-term recording of sympathetic activity in conscious rats. Dr. Misa Yoshimoto, shown below, obtained her Ph.D. with Dr. Miki and is currently a post-doctoral fellow in our laboratory. The laboratory is now equipped with custom designed amplifiers for this purpose and Dr. Yoshimoto is measuring renal and lumbar sympathetic nerve activity in conscious rats for as long as 6 weeks following instrumentation.
Current NCDC Investigators in the Osborn Laboratory
Pilar Guzman, DVM, Senior Scientist and Lab Manager
Misa Yoshimoto,Ph.D.; Post-doctoral fellow
Professor Kenju Miki, Ph.D., (Nara Women’s University); collaborator
Past NCDC Investigators in the Osborn Laboratory
Michael Hendel, Ph.D.; Post doctoral fellow
