Floyd Rector, MD

Dr. Floyd Rector was Chief of Nephrology at UCSF Parnassus from 1973-89. During this time, he conducted pioneering research the mechanisms of electrolyte transport in the renal tubules. Many of his trainees during this time period went on to distinguished careers of their own. Dr. Rector was President of the American Society of Nephrology from 1976-77 and became Chair of the Department at UCSF from 1989-1995.

On coming to UCSF: I had been at Southwestern Medical School in Dallas for many years, first as a medical student, then as an intern and resident in Medicine. After spending two years at the National Institutes of Health working in the Kidney and Electrolyte Laboratory, I returned to Dallas as a faculty member in the Department of Medicine. During that time a Division of Nephrology was established and I became Chief of the Division.

In 1973 Holly Smith contacted me about coming to San Francisco to replace Larry Earley as Chief of the Division of Nephrology in the Department of Medicine and as a Senior Scientist in the Cardiovascular Institute at UCSF. I found this to be a very attractive offer. The overall intellectual atmosphere of the Department of Medicine was a very high level, very research oriented. I knew several outstanding scientists (Isadore Edelman, Jay Nadel, John Severinghaus) in the CVRI, and the opportunity to interact with them was very appealing. Also Barry Brenner was chief of the Division of Nephrology at the San Francisco VA Hospital. I liked and respected Barry greatly and he was very encouraging for me to come to San Francisco. The many attractive features of UCSF as well as the opportunity to live in the Bay Area were irresistible. I came out, fell love with Sausalito, and we’ve been living there ever since.

On the state of nephrology at UCSF in the 1970’s: When I arrived there were three separate divisions of nephrology: one at Parnassus, one at San Francisco General Hospital and one at the VA Hospital. Michael Humphrey had just arrived to be chief at San Francisco General. Barry Brenner had been chief at the VA for 2 or 3 years. The divisions very isolated and interacted very little. On the initiative of Barry Brenner we began to integrate some of the activities of the three divisions and started a weekly combined research conference. When we established a presence on the Renal Transplant Service with the appointment of Bill Amend6 and Flavio Vincenti,7 fellows from all three divisions of nephrology rotated through the Kidney Transplant Service.

It was out of this sort of integrative activity that Barry and I began to collaborate on the textbook “The Kidney”. Again it was Barry’s initiative that got the book going. And he certainly carried the brunt of the workload.

On his research while at UCSF: Most of my research efforts were focused on the various mechanisms of sodium, bicarbonate, and chloride reabsorption in the proximal convoluted tubule. The research involved a variety of techniques, including micropuncture, micro perfusion of isolated tubules and membrane vesicles. Our research led to the concept that proximal reabsorption was primarily mediated by a sodium:hydrogen antiporter located in the luminal membrane. The operation of this antiporter accounted for the reabsorption of sodium and bicarbonate. The removal of bicarbonate from luminal fluid produced concentration gradients that then secondarily drove the passive reabsorption of chloride.

Robert Alpern8 and Reto Krapf initiated a series of studies using a pH sensitive fluorescent dye (BCECF) to measure intracellular pH. Using this technique in isolated perfused rabbit proximal tubules, we studied the mechanism by which bicarbonate left the cell across the basolateral membrane. We identified a coupled carrier by which two bicarbonate ions and one sodium ion moved across the basolateral membrane, driven by the negative electrical potential difference, without requiring any additional active transport.

The overall picture for proximal reabsorption that emerged was a single active transport process, the Na:K ATPase located on the basolateral membrane, which actively transported Na out and K into the cell. The concentration gradients and the resulting electrical potential difference (cell negative) supsequently passively drove all of the reabsortive processes: Na:H exchange on the luminal membrane, Na:2HCO3 co transport across the basolateral membrane, and diffusion of chloride out of the lumen along concentration gradients.

A second area of research, which was rather incidental, but which for me proved to be very exciting, was to work with Morrie Schambelan and Tony Sebastian in developing the concept that a distal chloride shunt, which by dissipating the distal electrical potential difference, interfered with potassium secretion and enhanced NaCl reabsorption. This gives rise to the syndrome of Type II pseudohypoaldosteronism with hyperkalemia and hypertension.

All of my research was done in collaboration with an outstanding group of research fellows and young faculty. Marty Cogan9 joined the faculty after completing his fellowship and was responsible for supervising most of the micro puncture studies. David Warnock10 came from the Kidney and Electrolyte Laboratory at NIH to help us set the isolated rabbit tubule micro perfusion technique. He also began to work with kidney membrane vesicles before leaving to become chief of Nephrology at the University of Alabama. Christine Berry got her PhD in physiology at Yale, joined the Division as a post doctoral fellow after which she became a faculty member. Christine was responsible for most of the studies involving micro perfusion of isolated rabbit tubules. Robert Alpern came as a fellow from Columbia and then joined the faculty. He did a number of important micro puncture studies, but most importantly was instrumental in developing the technique of measuring intracellular using the fluorescent dye BCECF. Bob left the Division to become chief of Nephrology at the University of Texas Southwestern Medical School in Dallas. With the long range goal of expanding the research activities of the Division into the area of molecular biology I recruited two research fellows with MD/PhDs: Harlan Ives11 from MIT and Columbia and Alan Verkman from MIT and Harvard.12

6. Dr. William Amend was interim Chief of Nephrology at UCSF from 1998-2003

7. Dr. Flavio Vincenti was president of the American Society of Transplantation 2007-2008

8. Dr. Robert Alpern was president of the ASN from 2000-2001 and won the ASN John Peters Award in 2008. He was Dean of UT-Southwestern Medical School (1998-2004) and is now Dean of the Yale School of Medicine (since 2004)

9. Dr. Martin Cogan was later Chief of Nephrology at San Francisco VA Medical Center (1988-1995) and winner of the ASN Young Investigator’s Award (1988).

10. Dr. David Warnock was later Chief of Nephrology at San Francisco VA Medical Center (1983-1988), Director of the Division of Nephrology at the University of Alabama at Birmingham and President of the National Kidney Foundation (2005-06)

11. Dr. Harlan Ives was Chief of Nephrology at UCSF from 1989-1998

12. Dr. Alan Verkman is Professor in the Division of Nephrology and winner of the ASN Young Investigator’s Award (1993)