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Caffeine effects on heart muscle energetics: species differences.
P Bonazzola1, J E Ponce-Hornos, M T Márquez
1Instituto de Investigaciones Cardiológicas, Facultad de Medicina, Universidad de Buenos Aires, Argentina.
Acta Physiologica, Pharmacologica Et Therapeutica Latinoamericana : Organo De La Asociacion Latinoamericana De Ciencias Fisiologicas Y [De] La Asociacion Latinoamericana De Farmacologia
|January 1, 1992
Summary
Caffeine negatively impacts rat heart muscle function and economy by affecting calcium handling. However, it shows a slight positive effect on toad heart muscle, suggesting species-specific mechanisms.
Area of Science:
- Cardiovascular Physiology
- Pharmacology
- Cellular Metabolism
Background:
- Caffeine is a widely consumed stimulant known to affect cardiac function.
- Understanding caffeine's impact on cardiac energy expenditure and mechanical properties is crucial for cardiovascular research.
Purpose of the Study:
- To investigate the effects of caffeine (1mM) on energy expenditure and mechanical parameters in rat and toad perfused heart ventricles.
- To explore species-specific differences in caffeine's cardiac effects, particularly concerning contractile economy and calcium handling mechanisms.
Main Methods:
- Isolated perfused rat and toad heart ventricles were subjected to various stimulation frequencies.
- Measurements included developed tension, rates of contraction and relaxation, active and resting heat production, and tension-time integral.
- Analysis focused on changes in contractile economy and energy expenditure in the presence of caffeine.
Main Results:
- Caffeine significantly depressed developed tension and contraction/relaxation rates in rat ventricles, indicating impaired contractility.
- In rat ventricles, caffeine decreased contractile economy, evidenced by increased active heat production relative to tension.
- Toad ventricles exhibited a slight positive inotropic effect with caffeine, and contractile economy remained unchanged.
Conclusions:
- Caffeine's negative impact on contractile economy in rat ventricles suggests inhibition of the sarcoplasmic reticulum Ca2+ pump, necessitating alternative ATP-consuming calcium removal pathways.
- The absence of these effects in toad ventricles indicates a different or less active SR-Ca pump system, highlighting species-specific responses to caffeine.
- Caffeine increased resting heat production in both species, correlating with the degree of sarcoplasmic reticulum activity.