Perelman School of Medicine Affiliations
Mahoney Institute of Neurological Sciences
Cell and Molecular Biology Graduate Group
Neurosciences Graduate Group
Pennsylvania Muscle Institute
B.A., Knox College, 1965
M.A., University of Illinois, 1966
M.D., Stanford University, 1971
Established Investigator of the American Heart Association
Jacob Javits Neuroscience Investigator Award (1989-1996)
Dean's Award for Excellence in Teaching of the Basic Sciences,
Society of General Physiologists
This cell physiology laboratory studies excitation-contraction
(E-C) coupling in vertebrate skeletal muscle and the role
of the calcium ion (Ca) as an intracellular chemical messenger.
The methodology relies on optical, electrical and mechanical
measurements from living single muscle fibers. Current work
tests hypotheses about calcium and E-C coupling in fast twitch
fibers of frog muscle, with some work also carried out on
fiber types of other species (e.g., fast-twitch fibers of
mouse, super-fast fibers of toadfish and rattlesnake, slow
twitch fibers of mouse and toadfish).
areas of active investigation include: (a) use of laser-scanning
microscopy to study myoplasmic calcium "sparks",
which are brief localized increases in fluorescence measurable
with a Ca-indicator such as fluo-3 and thought to reflect
the opening of one or a few Ca release channels of the sarcoplasmic
reticulum (=ryanodine receptors, RyRs); (b) estimation of
local Ca movements within the sarcomere by means of computer
modeling; (c) the role that myoplasmic Ca levels play in
activation and inactivation gating of RyRs; (d) the possibility
that either activation or inactivation of RyRs may vary with
the RyR isoform composition (RyR1, RyR3, etc.).
Hollingworth, S., U. Zeiger, and S. M. Baylor. 2008. Comparison of the myoplasmic calcium
transient elicited by an action potential in intact fibres of mdx and normal mice. J. Physiol.
Baylor, S. M. and S. Hollingworth. Simulation of Ca2+ movements within the sarcomere of fast-
twitch mouse fibers stimulated by action-potentials. J. Gen. Physiol. 130:283-302, 2007
Hollingworth, S., W. K. Chandler and S. M. Baylor. 2006. Effects of tetracaine on calcium
sparks in frog intact skeletal muscle fibers. J. Gen. Physiol. 127:291-307.
S. M., Hollingworth, S. Sarcoplasmic reticulum calcium release
compared in slow-twitch and fast-twitch
fibres of mouse muscle. J. Physiol. 551:125-138, 2003.
Hollingworth, S., K. R. Gee, and S. M. Baylor. 2009. Low-affinity Ca2+ indicators compared in
measurements of skeletal muscle Ca2+ transients. Biophys. J. 97:1864-1872.
S. M., Hollingworth, S., Chandler, W. K.. Comparison of modeled
and measured calcium sparks in intact skeletal muscle fibers
of the frog. J. Gen. Physiol. 120:349-368, 2002
A., Dantzig, J. A., Hollingworth, S., Baylor, S. M.,
Goldman, Y. E., Mitchison, T. J.,Straight, A.
small-molecule inhibitor of skeletal muscle myosin
II. Nature Cell Biology,4(1):83-88, 2002.
S., Peet, J., Chandler, W. K., Baylor, S. M. Calcium
sparks in intact frog skeletal muscle fibers. J. Gen. Physiol.,
S., Soeller, C., Baylor, S. M., Cannell, M.B. Sarcomeric
Ca2+ gradients during activation of frog skeletal muscle
fibres imaged with confocal and 2-photon microscopy. J.
Physiol., 526:551-560, 2000.
Click here for
a full list of publications
(searches the National Library of Medicine's PubMed database.)