1. Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73190;
2. Pulmonary Division, Beth Israel Deaconess Medical Center, and
3. Ina Sue Pelmutter Laboratory, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02215;
4. Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, Wisconsin 53706; and
5. Department of Pediatrics, State University of New York, Health Science Center at Brooklyn, Brooklyn, New York 11203-2098