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Myocardial contractile depression from high-frequency vibration is not due to increased cross-bridge breakage.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Campbell, Kenneth B. Wu, Yuguo Kirkpatrick, Robert D. Slinker, Bryan K. |
| Copyright Year | 1998 |
| Abstract | Experiments were conducted in 10 isolated rabbit hearts at 25 degrees 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 [delta Pd(t), a sustained decrease in pressure that was not at the perturbation frequency] and an infrequency response [delta Pf(t), that part at the perturbation frequency]. delta Pd(t) represented the effects of contractile depression. A cross-bridge model was applied to delta Pf(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. delta Pd(t) was strongly affected by whether the responses were activated by Ca2+ or by Sr2+. In the Sr(2+)-activated state, delta Pd(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 delta Pd(t) or, when it was significant, participated by reducing delta Pd(t) rather than contributing to its magnitude. Furthermore, there was no difference in cross-bridge cycling rate constants when the Ca(2+)-activated state was compared with the Sr(2+)-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 delta Pd(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. |
| Starting Page | 1 |
| Ending Page | 4 |
| Page Count | 4 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://ajpheart.physiology.org/content/ajpheart/274/4/H1141.full.pdf |
| PubMed reference number | 9575917v1 |
| Volume Number | 274 |
| Issue Number | 4 |
| Part | 2 |
| Journal | The American journal of physiology |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Calcium ion Cardiomyopathies Contribution Delta aminolevulinate/Creatinine:SRto:24H:Urine:Qn Delta aminolevulinate:SRat:24H:Urine:Qn Depressive disorder Heart Hertz (Hz) Myocardium gamma-delta T-Cell Receptor |
| Content Type | Text |
| Resource Type | Article |
