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Who is L. Gabriel Navar?
From Agriculture to Biomedical Research

Luis Gabriel (Gabby) Navar was born in El Paso, Texas. In his earlier years, Gabby had little contact with anything related to science or medicine. He was mainly interested in agriculture and that was because of his father’s involvement in farming and ranching. He did enjoy his science and math courses in high school though.

Studying Agriculture
Gabby chose to attend Texas A&M University in College Station, TX, because of its well-known agricultural program. He graduated from college in 1962. Initially Gabby planned to study some discipline associated with agriculture. Instead his father advised him to go into veterinary medicine because he could combine his interests in agriculture and science. Gabby took the advice and enrolled in veterinary school.

During his studies, Gabby found that he preferred the rigorous biomedical courses, like physiology, pharmacology, biochemistry, and neuroanatomy, instead of the clinical coursework. It was that realization that made him decide to pursue a career in scientific research.

Choosing the Right Program and Mentor
Since physiology was his favorite subject, Gabby investigated graduate programs in this field. After researching the various departments and universities, he decided to go to the University of Mississippi to study under Dr. Arthur Guyton. Dr. Guyton’s famous Textbook of Medical Physiology was a great influence on Gabby’s decision to go there. In addition, Dr. Guyton’s personal style of communicating directly with students won Gabby over.

During the next few years, Gabby developed his interests in renal physiology and the unique role of the kidney in the regulation of body fluid volumes. Gabby received his Ph.D. in 1966. He remained strongly influenced by Dr. Guyton, who remained Gabby’s mentor not just during his graduate student years but during his postdoctoral training and during his early years as a faculty member.

Reaching the Top
Following the completion of his training, Dr. Navar served on faculty at the University of Mississippi for several years. Then, in 1974, he joined the faculty at the University of Alabama at Birmingham in the Department of Physiology and Biophysiology and the Nephrology Research and Training Center.

He remained there until 1988, when he accepted the position as Chair of the Physiology Department at Tulane University Health Sciences Center in New Orleans, LA. Dr. Navar has been chair there for over 15 years now. He is also Co-Director of the Tulane Renal and Hypertension Center of Excellence.

Research
Even though he is the Chair, Dr. Navar still runs a very active research program. His laboratory investigates the hormonal and paracrine mechanisms regulating renal hemodynamics, glomerular filtration rate, and sodium excretion with specific focus on the tubuloglomerular feedback mechanism and its role in renal autoregulation.

Another area of interest regards the intrarenal mechanisms mediating changes in sodium excretion that occur in response to changes in arterial pressure, a phenomenon termed "pressure natriuresis." Recent studies support a role for intrarenal nitric oxide in mediating arterial pressure-related changes in sodium excretion. Intense recent activity has been focused on the pathophysiology of hypertension and altered kidney function in angiotensin II-dependent hypertension. Using an angiotensin II-infused model of hypertension, the role of altered internalization and formation of angiotensin II in mediating changes in renal function is being evaluated.

Service to Physiology
Dr. Navar has been an active member of the APS since 1966, serving on many committees, in the Renal Section, and in the publications program. In 1991 the entire membership elected him to serve on the APS Council to assist in running the Society. The members then elected him again in 1998 to serve as President.

During his presidency, Dr. Navar coordinated an effort to increase the membership of the Society, enabling APS to hit the 10,000 member mark. He also oversaw the granting of full membership benefits to overseas members, allowing them to vote in elections, serve on committees, and serve on Council or as President.

Since becoming a Chair in 1988, Dr. Navar has been active also in a society composed of all the chairs of physiology departments, called the Association of Chairs of Departments of Physiology (ACDP). He was elected to that organization’s Council, as President-elect, and as President in 1996-97. He currently serves as the ACDP representative to the Council of Academic Societies of the American Association of Medical Colleges. In 2003, he was given the highest award the ACDP has, the Distinguished Service Award, for his service to the ACDP and the discipline of physiology.

Away From Work
Outside of work, Dr. Navar’s interests include traveling (he routinely travels all over the world), meeting with his many friends and colleagues.

He also likes fishing and playing racquetball. He spends a lot of time with his family and especially his grandchildren, whom he adores.

Advice for Postdoctoral Fellows
The postdoctoral fellowship years are also very critical ones in career development because there must be a clear emergence into an independent line of investigation. This is a very difficult challenge, considering that previous projects have been strongly influenced by the mentor. Nevertheless, a good mentor will steer an emerging scientist into a specific area of investigation that can be related to, but distinct from, the mentor’s main area of investigation. Eventually, the quest to pursue specific new questions with unique approaches leads to developments and studies that distinguish the fellow and new investigator from the mentor. Throughout these years, the ability to define specific areas of investigation can be honed by encouraging the graduate student and postdoctoral fellow to prepare and submit fellowship proposals to various grant agencies.

Recent Publications
1. Navar, L.G. The role of the kidneys in hypertension. J. Clin. Hypertens. (Greenwich) 7(9):542-549, 2005.

2. Nishiyama, A., K.E. Jackson, D.S. Majid, M. Rahman, and L.G. Navar. Renal interstitial fluid ATP responses to arterial pressure and tubuloglomerular feedback activation during calcium channel blockade. Am. J. Physiol. Heart Circ. Physiol. doi:10.1152, Oct 7, 2005.

3. Kopkan, L., A. Castillo, L.G. Navar, and D.S. Majid. Enhanced superoxide generation modulates renal function in angiotensin II - induced hypertensive rats. Am. J. Physiol. Renal Physiol. doi:10.1152, Aug 16, 2005.

4. Fuller, A.J.,B.C. Hauschild, R. Gonzalez-Villalobos, M.S. Awayda, J.D. Imig, E.W. Inscho, and L.G. Navar. Calcium and chloride channel activation by angiotensin II-AT1 receptors in preglomerular vascular smooth muscle cells. Am. J. Physiol. Renal Physiol. 289(4):F760-F767, 2005.

5. Prieto-Carrasquero, M.C., H. Kobori, Y. Ozawa, A. Gutierrez, D. Seth, and L.G. Navar. AT1 receptor-mediated enhancement of collecting duct renin in angiotensin II-dependent hypertensive rats. Am. J. Physiol. Renal Physiol. 289(3):F632-F637, 2005.

6. Gonzalez-Villalobos, R., R.B. Klassen, P.L. Allen, L.G. Navar, and T.G. Hammond. Megalin binds and internalizes angiotensin II. Am. J. Physiol. Renal Physiol. 288(2):F420-F427, 2005.

7. Feng, M.G., and L.G. Navar. Angiotensin II-mediated constriction of afferent and efferent arterioles involves T-type Ca²⁺ channel activation. Am. J. Nephrol. 24(6):641-648, 2004.

8. Navar, L.G.. The intrarenal renin-angiotensin system in hypertension. Kidney Int. 65(4):1522-1532, 2004.

9. Feng, M.G., M. Li, and L.G. Navar. T-type calcium channels in the regulation of afferent and efferent arterioles in rats. Am. J. Physiol. Renal Physiol. 286(2):F331-F337, 2004.

10. Kobori, H., M.C. Prieto-Carrasquero, Y. Ozawa, and L.G. Navar. AT1 receptor mediated augmentation of intrarenal angiotensinogen in angiotensin II-dependent hypertension. Hypertension 43(5):1126-1132, 2004.