\mechanical measurements from isolated cardiac myocytes using a
pipette attachment system.
Palmer, Roy E., Allan J. Brady, and Kenneth P. Roos.
The Cardiovascular Research Laboratory and Department of
Physiology, School of Medicine, University of California at Los
Angeles, Los Angeles, CA 90095-1760
APStracts 2:0301C, 1995.
Single rat left-ventricular myocytes were attached at both ends using
a newly described double-barreled micropipette technique. This
attachment procedure enabled the measurement of the active and
passive mechanical properties of chemically skinned cells which
showed little structural deformation. The force and oscillatory
stiffness (100 Hz) of the cells were measured with a high
signal/noise ratio and the sarcomere length throughout the entire
cell was monitored using image analysis. The passive properties were
investigated from the resting sarcomere length to above 3 m. Analysis
of the sarcomere behavior indicated a high level of homogeneity
throughout the cell. The attachment method supported the full
activation of the cells by increased free calcium (pCa 4.5), which
produced 22.3 mN mm-1 (mean sarcomere length 2.11 m). A force/pCa
relationship was determined which when fitted according to the Hill
equation gave parameters of: nH = 2.62, pCa50 = 5.58. The described
techniques allow the accurate study of the mechanical properties of
single myocytes with increased fidelity and reliability over the pre
-existing methods.
Received 12 June 1995; accepted in final form 10 August 1995.
APS Manuscript Number C331-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 24 August 1995.