Robert F. Furchgott: A Pharmacologist’s Pharmacologist
Robert Furchgott generally describes his contributions to pharmacology largely as the result of happenstance—or even of experimental “accidents” just waiting to happen, and he speaks of his “good luck” in stumbling upon the work that led, in 1998, to bestowal of the Nobel Prize in Physiology or Medicine (to Furchgott, as well as to Louis Ignarro and Ferid Murad). If you read any of the biographical material available on Furchgott, however, it is clear that such “accidents” could have easily been dismissed by minds any less prepared or less enthusiastic for research. (For an autobiographical sketch, see http:/www.nobel.se/medicine/laureates.) Receiving his PhD in 1940, Furchgott began his career at a time when the existence of cell surface receptors was theoretical, well before radioisotopes became commonplace in biomedical research, and long before molecular biology would supply techniques for studying individual macromolecules. He had attained wide recognition in his profession and had been founding Chair of the Department of Pharmacology at SUNY Downstate for over two decades when, at an age when many begin the transition into retirement, he embarked on the work that would open up a new and vigorous field of research in nitric oxide signaling. During the colder months, he now works from an office at the Medical University of South Carolina in his hometown of Charleston (where the following interview transpired), keeping in close contact with his laboratory at SUNY, where he resides during the academic year.
MI: What was your view of science when you were growing up?
RF: I had and early interest in natural history. I grew up, until I was thirteen, in Charleston, South Carolina, where there was a very good summer program for young people at the Charleston Museum. Some very good naturalists at the Museum took us on field trips, and I became a shell collector and a bird watcher and generally interested in nature and science. My parents gave me a small microscope and a chemistry set and things like that, and there were articles on science in the Sunday New York Times, which got me interested, too. I also remember being impressed by the books Microbe Hunters and Arrowsmith.
MI: You grew up in the Depression Era—did that influence your decision to pursue science?
RF: No, I just liked science. In high school, in Orangeburg, S.C., I had a good science teacher for physics, and chemistry interested me. Because my father’s business was poor during the Depression, I couldn’t afford to go to my first-choice school as a freshman, the University of North Carolina, and so I went to the University of South Carolina as an in-state student. By the end of that year, my family had moved to North Carolina, and so I went to UNC for the rest of my undergraduate college years; my major interest was physical chemistry. I graduated in 1937, still during the Depression, and graduate assistantships were not easy to find. But I was lucky that someone in the chemistry department at UNC directed me to Henry Bull, who was in the biochemistry department at Northwestern.
MI: How did you feel about going into a biochemistry department after having prepared yourself to be a physical chemist?
RF: Well, I liked biochemistry very much, and I was able to focus on sort of the physical chemistry parts of biochemistry at Northwestern; I began doing some work on egg albumin proteins. But in the summer of 1938, Henry Bull was invited to give a talk at an extended protein symposium at Cold Spring Harbor Laboratory. I was able to go along because Henry had arranged that I could get room and board there if I would take care of the slide projector during the symposium.
MI: So, you got to go to all the talks—and had to pay attention!
RF: Oh, I took part in discussions sometimes. I criticized Langmuir (Irving Langmuir, Nobel laureate 1932) once on his interpretation of some of the monolayers of proteins that he presented—I had worked on the subject to some extent in one of the courses I took. I got to know a number of people who were quite distinguished even then, and some who would become so later on.
MI: Were there people at that time presenting work that you particularly wanted to pursue?
RF: Actually, I had been thinking of trying to get into the physical chemistry of proteins, but my thesis work progressed in another area because the head of Cold Spring Harbor Laboratory, Dr. Eric Ponder, and a physician scientist named Harold Abramson invited me to stay on after the symposium and do some laboratory work. I was asked to study whether the membrane of red blood cells remained the same when you made so-called “ghosts” of blood cells by hemolysis—I was to compare the movement of ghost cells with that of intact erythrocytes in an electrophoresis cell.
MI: People were trying to find out the functions of cell membranes at that time…
RF: Yes. I started to work the summer there and I became interested in the shape changes in red blood cells under the microscope. Red blood cells are, of course, biconcave disks, but when you spin them down in a centrifuge and resuspend them in isotonic saline, and then place a drop of the diluted suspension under a glass cover slip on a microscope slide, they go through a sequence of shape changes from biconcave disks to perfect spheres. I continued to study red blood cells when I returned to Northwestern after the summer, and the shape-change work became the subject of my thesis, with Dr. Ponder as a mentor. So, I was very lucky early on about meeting people at Cold Spring Harbor and discussing things with them, and I went to the two succeeding symposia after the one on proteins—one was on the biochemical aspects of endocrinology and another one was on cell membranes. At the last one, Davson and Danielli described their model of the membrane lipid bilayer. I had met them at the first symposium, as well. Anyway, although Northwestern was officially my school, I was given credit on my thesis for my summer research at Cold Spring Harbor and I was able to complete my PhD in three years. I graduated in 1940 wanting to get a job in a laboratory where they were studying cell membranes, but it was hard to get fellowships or assistantships.
MI: Did the difficulty have anything to do with the fact that World War II was starting up at that time?
RF: No, I don’t think so. The war had started in Europe, but we didn’t get into it until the Japanese attacked Pearl Harbor in December of 1941. It was at a FASEB meeting, in New Orleans in 1940, that I had an interview with Dr. Ephraim Shorr for a postdoctoral position, and I began working with him at Cornell University Medical School in the fall. But when the war did begin, I was deferred from military service for the first year or so because I had no sight in one eye because of a detached retina. Later, around 1944 or so, I was called up again by the draft board, but by that time we were working on irreversible shock of the circulatory system due to blood loss and trauma—it was a wartime project partly supported by government funds, so I was deferred because of the research. I had also begun to teach in the Physiology Department at the Medical School, where they were short of faculty because of the war.
MI: So, from having started out with an interest in physical biochemistry, you were now really becoming a physiologist.
RF: In some ways—I still liked the idea of biochemistry, but the work was becoming physiologic as well. We were doing a lot of work on tissue metabolism, such as it was at that time. And Shorr was very interested even before the war in the metabolism of carbohydrates and fatty acids in relation to diabetes and bio-energetics. We were working with the Warburg apparatus, where you made tissue slices and put them in a vessel hooked up to a manometer, so that you could measure the uptake of O2 in the system or CO2 production. We were also doing some of the very first work with radioactive phosphorus to study turnover of ATP and the uptake of phosphate.
MI: That was the cutting edge, wasn’t it?
RF: Yes, it was. My first paper in the Journal of Biological Chemistry (published in 1943) had to do with the turnover of radioactive phosphate. But I was also becoming very interested in smooth muscle from working on circulatory shock. We thought we had two factors, produced in dogs undergoing hemorrhage, that regulated the course of irreversible shock. We assayed these plasma factors by monitoring their effects on the peripheral vasculature of the rat mesentery; Benjamin Zweifach, a wonderful vascular physiologist recruited to Cornell by Shorr, had developed a system where you could look, under the microscope, at how these dog plasma factors, upon injection into the tail vein of anesthetized rats, would alter the sensitivity of rat mesentery vessels to topically applied epinephrine. We observed the time-dependent appearance of both vasoexcitatory and vasodepressor materials (VEM and VDM, respectively).
MI: And how far did you get in identifying what those materials were?
RF: Not very far. Abraham Mazur, one of my colleagues, fractionated VDM down to a pure protein—and it proved to be ferritin. We could never get ferritin to cause a fall in blood pressure, however, and I had some evidence that VEM might be a small polypeptide coming from kidney, but it was never clear.
But the work on VEM and VDM was responsible for getting me into the pharmacology of smooth muscle. Originally I thought that maybe we could detect the effects of VEM and VDM on isolated smooth muscle preparations, such as isolated segments from the rabbit duodenum. We set up these in classical organ bath systems, recording contractions with isotonic levers on a kymograph, but we didn’t see any response to VEM or VDM. But we were able to use this system to test certain agents—fatty acids and Krebs-cycle intermediates—for the ability to be used as energy sources for contraction. We were also doing work on acetylcholine and epinephrine (we didn’t use norepinephrine at that time) on smooth muscle from these intestinal strips, and we did some studies on the exhaustion of carbohydrate-type sources of energy to see what that did to the actions of hormones and neurotransmitters. When I moved on to Oliver Lowry’s Department of Pharmacology at Washington University, in 1949, I continued the work on the effects of drugs on intestinal smooth muscle, but also began studies on isolated vascular smooth muscle, using helical strips of rabbit thoracic aorta.
MI: So, you were regarded as a “pharmacologist” by the time you went to Washington University.
RF: Yes, but I used the summer before I went there to read Goodman and Gilman. I had never had a pharmacology course!
MI: But soon you would be concentrating on problems that we now consider very basic to pharmacology. One was “receptor reserve.” What was that about?
RF: Well, based on the responses of tissues to agonists and antagonists, you could try to develop a theoretical analysis that would allow you to estimate responses in terms of receptor binding. With certain agonists, you could essentially attain a full response (contraction or relaxation) of smooth muscle and still have a large fraction of receptors not occupied by the agonist—so that there was a receptor reserve. In other words, you could block a certain fraction of receptors and still get a full response with strong agonists. And certain agonists that acted on the same receptor might show different levels of reserve. These were new concepts at that time in the 1950s, just around the time R.P. Stephenson developed the idea of efficacy and partial agonists and so on. I remember, when I moved to the State University of New York (SUNY) Downstate in 1956, the head of the Physiology Department was a very distinguished scientist, Chandler Brooks. He was one of the people who selected me as head of Pharmacology there, and he always liked to argue a bit and say that there may be no such thing as specific receptors. Nobody then dreamed that we were going to be able to isolate and characterize all of the receptors that we know today!
MI: You worked, over decades, to establish aspects of pharmacology that we take for granted today. If you hadn’t made your Nobel Prize–winning discovery of nitric oxide as an endothelium-derived relaxing factor (EDRF), would you yourself have seen that finding as a career culmination, or would you regard it as one among many contributions that you had made?
RF: It would be the biggest finding anyway, and as a matter of fact it was recognized to be important with several prizes before the Nobel Prize was awarded. I consider myself very lucky to have happened across—rather accidentally—our work in that direction.
MI: How did you get into studying EDRF?
RF: Actually, we had begun with studies on strips of guinea pig tracheal smooth muscle, and we were comparing different catecholamines for their potency as relaxing agents.
MI: This was at SUNY—in the late 1970s, right?
RF: Yes, and when we would compare the potencies of epinephrine, norepinephrine, and some other catecholamines as relaxing agents at beta receptors (having blocked alpha receptors irreversibly with dibenamine), we would find that the relative potencies could vary considerably from one experiment to another, indicating that there was more than one type of beta receptor giving rise to relaxation. Because of this unexpected finding on tracheal smooth muscle (i.e., variability in relative responsiveness to a series of drugs), I began to wonder whether our early findings on the relative potencies of catecholamines on the smooth muscle of rabbit aorta were correct.
MI: So, you decided to return to your previous work on rabbit aorta to verify the responsiveness of smooth muscle to those drugs?
RF: I thought we better re-look at this business about receptors and catecholamines in vascular smooth muscle. In our early studies on relaxation, we similarly blocked the alpha-receptors by pretreatment with dibenamine. Additionally, we had always used acetylcholine in the past (after blocking the alpha receptors with dibenamine) to cause contraction of our aorta preparations, and it was on that contracted muscle that we studied relaxation with the adrenergic agents. In going back to do this re-examination, my technician was to conduct some preliminary tests to make sure that the aorta preparations contracted well with both norepinephrine and acetylcholine before pretreating them with dibenamine, but the technician, deviating from the protocol I had prepared, after contracting the preparations with norepinephrine (since the alpha receptors were not yet blocked), failed to wash out the nor-epinephrine before testing acetylcholine for its contracting effect. Surprisingly, the acetylcholine caused the contracted muscle tissue to relax—contrary to the decades-long experimental use of acetyl-choline to elicit contraction!
MI: And you followed up on this “experimental mishap” as a real phenomenon because in vivo…
RF: That’s right! In vivo, acetylcholine is a wonderful vasodilator; it drops blood pressure very dramatically when given intravenously, but this was the first time that we had ever seen relaxation of rabbit aorta in response to acetylcholine, and so I thought we were on to something. Now, in our early studies with acetylcholine we had always used helical strips of aorta, but by 1978 we were using transverse rings from the aorta. The next day we tried preparations of helical strips and transverse rings from the same aorta and contracted both types of preparations with norepinephrine: with the helical strips, acetylcholine caused no relaxation, but with the rings we always saw relaxation. It took a little while to demonstrate that we had unknowingly been rubbing the endothelium away in our procedure for making helical strips, and that was the beginning of our studies on endothelium as a source of something that caused smooth muscle relaxation. We called it EDRF, for endothelium-derived relaxing factor. (We considered calling it EDRS, for endothelium-derived relaxing substance, but my initials are RF!)
MI: Were your results accepted right away?
RF: Not right away—my 1980 paper was submitted to Nature and it went out to two reviewers. One responded with criticism saying we must have done something wrong—that this couldn’t be. The other reviewer was quite in favor of our results. I had hoped that the paper would be accepted as an Article, but the editor commented that my writing was too colloquial, and that it would have to be shortened into a Letter. Anyway, I revised it, and on the approval of the editor and one reviewer it was published.
MI: And you knew that EDRF was going to be taking up your time from then on?
RF: Yes, we did. We knew that what was coming out of the endothelium was very fleeting, and we had some ideas.
MI: So, how long did it take you to find out what EDRF was?
RF: Oh, it’s embarrassing that it took so long! Really. Well, I guess it’s not that embarrassing—there were many people working at that time on EDFR, and some very good pharmacologists and biochemists, and they hadn’t figured it out, either.
MI: It was the first of its kind, right?
RF: Well, Lou Ignarro had a very active group working on nitro-sothiols, among other things, and he got into the thick of the action, and we both quite independently, at the same meeting in 1986, proposed that EDRF is nitric oxide.
MI: When you first discovered EDRF, you were already well established and at a time where others might begin to think about retirement. If you hadn’t made that initial discovery at that time, might you have retired?
RF: I don’t know. I think you’re right in what you perhaps infer. Many people were so much ahead of me on receptor work. Radioactive labeling and molecular biology were becoming more prevalent, and I didn’t feel that comfortable in those areas. I did in fact retire from the chairmanship at SUNY in 1982, although I still taught medical students until 1989.
MI: So, the lesson for researchers is to persevere—that the big discovery could still be coming?
RF: Well, we’re still doing some research work!
- © American Society for Pharmacology and Experimental Theraputics 2004
