Key result
Isoflurane and sevoflurane caused a greater depression of contractility and a greater decrease in peak intracellular calcium in tissues from animals with pressure-overload hypertrophy.
Why the study?
Do isoflurane and sevoflurane affect contractility and intracellular calcium differently in pressure-overload hypertrophy compared to normal myocardium?
Do isoflurane and sevoflurane affect contractility and intracellular calcium differently in pressure-overload hypertrophy compared to normal myocardium?
Answers are grounded in this paper and cite their sources.
Changes in intracellular calcium and altered calcium sensitivity mediate the exaggerated depressant effects of volatile anesthetics on contractility in pressure-overload hypertrophy.
BACKGROUND: Depression of myocardial contractility as a result of isoflurane appears to be greater in myocardial hypertrophy, and the cellular basis for this difference in susceptibility is not clear. In this study we examined the effects of isoflurane and sevoflurane on contractility and intracellular calcium in an animal model of pressure-overload hypertrophy. METHODS: Pressure-overload hypertrophy was established in young male ferrets by banding the main pulmonary artery for 1 month and the effects of isoflurane and sevoflurane on contractility and intracellular calcium ([Ca]i) were examined in isolated right ventricular papillary muscles, trabeculae, and myocytes. Intracellular calcium was measured with the bioluminescent photoprotein aequorin in isolated papillary muscles, and also with the fluorescent indicator fluo-3 in isolated ventricular myocytes. In addition, Ca sensitivity was assessed in isolated trabeculae after disruption of the surface membrane with a nonionic detergent (skinned fibers). RESULTS: In the presence of isoflurane and sevoflurane, papillary muscles from banded animals exhibited a greater depression of contractility and isolated ventricular myocytes showed a greater decrease in peak [Ca]i. Furthermore, baseline calcium sensitivity was decreased and the slope of the relationship between [Ca] and force was increased in skinned trabeculae from banded animals. Isoflurane decreased calcium sensitivity in trabeculae from both normal and banded animals. CONCLUSIONS: These results suggest that changes in [Ca]i and altered calcium sensitivity are both responsible for the exaggerated effects of some volatile anesthetics on contractility in pressure-overload hypertrophy.
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Hannon et al. (2004) studied Pressure-overload hypertrophy. Isoflurane and sevoflurane vs. Normal animals was evaluated on Contractility and intracellular calcium ([Ca]i). Isoflurane and sevoflurane caused a greater depression of contractility and a greater decrease in peak intracellular calcium in tissues from animals with pressure-overload hypertrophy.
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