Dale J. Benos, Ph.D. (1950-2010).

THE UNIVERSITY OF ALABAMA AT BIRMINGHAM, the American Physiological Society, and physiologists all over the world were stunned by the untimely passing of Dale J. Benos on October 7th, 2010 (Fig. 1). In his memorial service, held November 12th, 2010 at the University of Alabama at Birmingham, a number of distinguished scientists, educators and administrators, and medical students delivered moving tributes to his intellect, his contributions to science, and his warm and engaging personality. A perspective by Dr. Catherine M. Fuller, his long-time collaborator and friend, summarized the eulogies and is a fitting memorial to Dale (6). Many disciplines claimed Dale as “one of their own” because of his fundamental contributions and the number of people he trained in many different areas. The lung community is no exception. In this brief editorial, we will summarize how his discoveries contributed significantly to our understanding of the fundamental mechanisms of lung fluid balance. While a graduate student in Dr. Tosteson’s laboratory at Duke University, Dale (in collaboration with Drs. Simon, Mandel, and Cala, his lifelong friends and collaborators) published a seminal paper on the inhibition of short-circuit current across the frog skin by amiloride and its structural analogs (3). This was the first insight into the fact that “slight structural modifications (of amiloride) can result in significant modifications of its effectiveness” (p. 43). Two short years later, Drs. Benos and Mandel published another seminal paper in Science (1) demonstrating that an analog of amiloride became an irreversible inhibitor of “the sodium entry site” (p. 199), the rate-limiting step in vectorial Na transport across epithelial tissues. Not bad for a graduate student! Even Dr. Tosteson must have been impressed (secretly, of course). At that time, Dale’s name and work on amiloride were well known to the people who established the field of lung ion transport: Dr. Mason showed that apical (but not basolateral) amiloride collapsed the spontaneous potential difference across polarized monolayers of alveolar type II (ATII) cells (14); Dr. Crandall and his collaborators showed that amiloride inhibited active sodium transport across monolayers of rat ATII cells (9); and Drs. Matthay and Staub provided the first demonstration that sheep lungs actively transported isoosmotic fluid secondary to vectorial ion transport and that amiloride blocked 50% of this process (18). A few years later, Drs. Sariban-Sohraby (still an active contributor to the field of lung fluid balance) and Benos (then an Assistant Professor at Harvard) published another seminal paper [this time in Nature (20)] in which they provided the first evidence of amiloride-sensitive single channel activity when apical membranes of A6 cells were reconstituted in a lipid bilayer. Even today, many bilayer setups are still present in Dale’s laboratory at the University of Alabama at Birmingham and have been used by his many students and collaborators to identify the mechanisms responsible for the regulation of sodium channels. I (Sadis Matalon) met Dale Benos in 1987 when I was on sabbatical at the University of Alabama at Birmingham. (I liked it so much I never left.) At that time Dale had isolated a Na channel protein from kidney papillae and developed specific antibodies which he used to demonstrate immunocytochemically the existence of sodium channel proteins in a variety of epithelial tissues (2, 22). Dale readily shared reagents, expertise, and even his only technician to help me with my studies on the identification and characterization of the epithelial sodium channels in lung epithelial cells (15–17, 19, 23). Figure 2 shows the first demonstration of immunoreactive proteins related to sodium channels in isolated ATII cells using Dale’s antibodies. Western blotting studies using this antibody showed the existence of a faint (but real) band around 150 kDa. Finally, Dale’s laboratory immunopurified a sodium channel protein from ATII cells, reconstituted the protein into bilayers, and showed that the reconstituted protein produced a Na conductance that was inhibited by amiloride and its analogs