Penn Medicine

Stephen M. Baylor, M.D.

Department of Physiology, University of Pennsylvania School of Medicine

Contact Information

Department of Physiology
University of Pennsylvania School of Medicine
A406 Richards Bldg.
3700 Hamilton Walk
Philadelphia, PA 19104-6085
Phone: (215) 898-5219
Fax: (215) 573-5851
Position: Professor


The Baylor laboratory studies excitation-contraction (E-C) coupling in vertebrate skeletal muscle and the role of calcium (Ca) as an intracellular effector. The methodology involves the measurement of optical, electrical, and /or mechanical signals from living single fibers of frog, fish, snake, and mouse. Of particular interest is how the myoplasmic Ca transient recorded with a fluorescent indicator can be used to quantify the rate of Ca release from the sarcoplasmic reticulum (SR), the diffusion of Ca within the sarcomere, the binding of Ca to sites on troponin and parvalbumin, and the re-uptake of Ca by the SR Ca pump. Areas of current activity include:

  1. characterization of the process whereby released Ca inactivates the SR release channels;
  2. comparison of myoplasmic Ca transients in fast- and slow-twitch fibers of mouse, and superfast-, fast- and slow-twitch fibers of fish and snake;
  3. use of confocal microscopy to measure Ca "spark" activity in minimally-activated fibers;
  4. estimation of local Ca movements within the sarcomere by means of confocal measurements and computer modeling.

Representative Publications

  1. Jong, D.-S., Pape, P., Baylor, S.M. and Chandler, W. K. Calcium inactivation of calcium release in frog cut muscle fibers that contain millimolar EGTA or Fura-2. J. Gen. Physiol., 106:337-388, 1995.
  2. Zhao, M., Hollingworth, S. and Baylor, S. M. Properties of tri- and tetra-carboxylate Ca2+ indicators in frog skeletal muscle fibers. Biophys. J., 70:896-916, 1996.
  3. Rome, L. C., Syme, D. A., Hollingworth, S., Lindstedt, S. and Baylor, S. M. The whistle and the rattle: the design of sound producing muscles. Proc. Natl. Acad. Sci., 93:8095- 8100, 1996.
  4. Hollingworth, S., Zhao, M. and Baylor, S. M. The amplitude and time course of the myoplasmic free [Ca2+] transient in fast-twitch fibers of mouse muscle. J. Gen. Physiol., 108:455-469, 1996.


Pennsylvania Muscle Institute
Perelman School of Medicine University of Pennsylvania
Director: E. Michael Ostap, Ph.D.

700A Clinical Research Building Philadelphia, PA 19104-6085 Phone: (215) 573-9758 Fax: (215) 898-2653