Journal article
Myocardial contractile depression from high-frequency vibration is not due to increased cross-bridge breakage
American journal of physiology. Heart and circulatory physiology, Vol.274(4), pp.H1141-H1151
04/01/1998
Handle:
https://hdl.handle.net/2376/113600
PMID: 9575917
Abstract
Experiments were conducted in 10 isolated rabbit hearts at 25°C to test the hypothesis that vibration-induced depression of myocardial contractile function was the result of increased cross-bridge breakage. Small-amplitude sinusoidal changes in left ventricular volume were administered at frequencies of 25, 50, and 76.9 Hz. The resulting pressure response consisted of a depressive response [ΔPd( t), a sustained decrease in pressure that was not at the perturbation frequency] and an in-frequency response [ΔP f ( t), that part at the perturbation frequency]. ΔPd( t) represented the effects of contractile depression. A cross-bridge model was applied to ΔP f ( t) to estimate cross-bridge cycling parameters. Responses were obtained during Ca2+ activation and during Sr2+ activation when the time course of pressure development was slowed by a factor of 3. ΔPd( t) was strongly affected by whether the responses were activated by Ca2+ or by Sr2+. In the Sr2+-activated state, ΔPd( t) declined while pressure was rising and relaxation rate decreased. During Ca2+ and Sr2+ activation, velocity of myofilament sliding was insignificant as a predictor of ΔPd( t) or, when it was significant, participated by reducing ΔPd( t) rather than contributing to its magnitude. Furthermore, there was no difference in cross-bridge cycling rate constants when the Ca2+-activated state was compared with the Sr2+-activated state. An increase in cross-bridge detachment rate constant with volume-induced change in cross-bridge distortion could not be detected. Finally, processes responsible for ΔPd( t) occurred at slower frequencies than those of cross-bridge detachment. Collectively, these results argue against a cross-bridge detachment basis for vibration-induced myocardial depression.
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Details
- Title
- Myocardial contractile depression from high-frequency vibration is not due to increased cross-bridge breakage
- Creators
- Kenneth B Campbell - Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, and, Department of Biological Systems Engineering, Washington State University, Pullman, Washington 99164Yiming Wu - Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, andRobert D Kirkpatrick - Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, andBryan K Slinker - Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, and
- Publication Details
- American journal of physiology. Heart and circulatory physiology, Vol.274(4), pp.H1141-H1151
- Academic Unit
- Veterinary Medicine, College of; Integrative Physiology and Neuroscience, Department of
- Identifiers
- 99900547910201842
- Language
- English
- Resource Type
- Journal article