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[Mechanical noise of the myocardium as an index of sarcoplasmic reticulum activity]
Abstract:
The effects of caffeine (0.5-12 mM) and cooling on the mechanical noise (MN) and relaxation rate of contractile response (RR) were studied in experiments on rat papillary muscles. Mean frequency of MN and RR were found to have similar temperature dependences from 12 to 32 degrees C. MN amplitude was more sensitive to the action of sarcoplasmic reticulum activity blocker, caffeine, than RR one. MN as an index of sarcoplasmic reticulum activity made it possible to demonstrate a competition between caffeine and local anaesthetics described earlier for skeletal muscles.
Insights
Caffeine and cooling affect rat heart muscle contractions. Mechanical noise, indicating sarcoplasmic reticulum activity, is more sensitive to caffeine than relaxation rate, suggesting a competition mechanism.
Area of Science:
- Cardiology
- Muscle Physiology
- Pharmacology
Context:
- Investigates the mechanical noise (MN) and relaxation rate (RR) of contractile responses in rat papillary muscles.
- Examines the influence of varying caffeine concentrations (0.5-12 mM) and temperature changes on muscle function.
Purpose:
- To elucidate the distinct effects of caffeine and temperature on cardiac muscle mechanical noise and relaxation.
- To assess the sensitivity of MN and RR to caffeine as a sarcoplasmic reticulum activity blocker.
- To explore potential interactions between caffeine and local anesthetics in cardiac muscle.
Summary:
- Both caffeine and cooling demonstrated similar temperature dependencies for the mean frequency of mechanical noise and relaxation rate between 12 and 32 degrees C.
- Mechanical noise amplitude showed higher sensitivity to caffeine, a sarcoplasmic reticulum activity blocker, compared to the relaxation rate.
- Mechanical noise serves as a reliable index for sarcoplasmic reticulum activity, enabling the observation of a competitive interaction between caffeine and local anesthetics.
Impact:
- Provides insights into the role of sarcoplasmic reticulum in cardiac muscle contractility and relaxation.
- Highlights the differential effects of pharmacological agents on specific aspects of muscle response.
- Establishes mechanical noise as a valuable tool for studying sarcoplasmic reticulum function and drug interactions in cardiac tissue.