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Volatile anesthetics decrease calcium content of isolated myocytes
M Katsuoka1, K Kobayashi, S T Ohnishi
1Membrane Research Institute, University City Science Center, Philadelphia, Pennsylvania 19104.
Anesthesiology
|June 1, 1989
Summary
Volatile anesthetics like halothane and caffeine affect cardiac calcium levels. Both substances decrease myocyte calcium content by impacting the sarcoplasmic reticulum, suggesting similar mechanisms of action.
Area of Science:
- Cardiology
- Pharmacology
- Cell Physiology
Background:
- The calcium transient is crucial for myocyte contraction.
- Volatile anesthetics are widely used in surgery.
- Caffeine is known to affect intracellular calcium handling.
Purpose of the Study:
- To investigate the effects of volatile anesthetics (halothane, enflurane, isoflurane) and caffeine on myocyte calcium levels.
- To compare the mechanisms of action of volatile anesthetics and caffeine on the sarcoplasmic reticulum.
Main Methods:
- Myocyte calcium transients were measured using the fluorescent dye Fura-2.
- Experiments involved pretreatment with anesthetics and caffeine to assess calcium release.
- Changes in resting calcium levels, calcium transient amplitude, and total myocyte calcium content were quantified.
Main Results:
- Halothane, enflurane, and isoflurane, along with caffeine, increased resting calcium levels and reduced the calcium transient amplitude.
- Pretreatment with halothane suppressed caffeine-induced calcium release, and vice versa, indicating similar effects on the sarcoplasmic reticulum.
- These agents decreased total myocyte calcium content by 10-70%.
Conclusions:
- Volatile anesthetics decrease cardiac sarcoplasmic reticulum calcium content by enhancing its calcium permeability.
- The mechanism of action for volatile anesthetics in myocytes shares similarities with caffeine's effects.
- These findings have implications for understanding anesthetic-induced cardiac dysfunction.