Vol. 92, Issue 6, 2491-2500, June 2002
Effects of volatile anesthetics on elastic stiffness in
isometrically contracting ferret ventricular myocardium
Anna E.
Bartunek1,2,
Victor
A.
Claes3, and
Philippe R.
Housmans1
1 Department of Anesthesiology, Mayo Foundation,
Rochester, Minnesota 55905; 2 Department of
Cardiothoracic and Vascular Anesthesia and Intensive Care Medicine,
University of Vienna, A-1010 Vienna, Austria; and
3 Laboratory of Human Physiology and
Pathophysiology, University of Antwerp, B-2020 Antwerp,
Belgium
The effects of
halothane, isoflurane, and sevoflurane on elastic stiffness, which
reflects the degree of cross-bridge attachment, were studied in intact
cardiac muscle. Electrically stimulated (0.25 Hz, 25°C),
isometrically twitching right ventricular ferret papillary muscles
(n = 15) at optimal length
(Lmax) were subjected to sinusoidal length
oscillations (40 Hz, 0.25- 0.50% of Lmax peak to peak). The amplitude and phase relationship with the resulting force oscillations was decomposed into elastic and viscous components of total stiffness in real time. Increasing extracellular
Ca2+ concentration in the presence of anesthetics to
produce peak force equal to control increased elastic stiffness during
relaxation, which suggests a direct effect of halothane and sevoflurane
on cross bridges.
sinusoidal length oscillations; cross bridges; calcium
