OBJECTIVES: We examined the effects of energy delivered with electrical defibrillation on myocyte contractility and intracellular Ca2+ dynamics. We hypothesized that increasing the defibrillation energy would produce correspondent reduction in myocyte contractility and intracellular Ca2+ dynamics. DESIGN: Randomized prospective study. SETTING: University-affiliated research laboratory. SUBJECTS: Ventricular myocytes from male Sprague-Dawley rat hearts. MATERIALS AND METHODS: Ventricular cardiomyocytes loaded with Fura-2/AM were placed in a chamber mounted on an inverted microscope and superfused with a buffer solution at 37 degrees C. The cells were field stimulated to contract and mechanical properties were assessed using a video-based edge-detection system. Intracellular Ca2+ dynamics were evaluated with a dual-excitation fluorescence photomultiplier system. Myocytes were then randomized to receive 1) a single 0.5-J biphasic shock; 2) a single 1-J biphasic shock; 3) a single 2-J biphasic shock; and 4) a control group without shock. After the shock, myocytes were paced for an additional 4 mins. RESULTS: A single 0.5-J shock did not have effects on contractility and intracellular Ca2+ dynamics. Higher energy shocks, i.e., 1- or 2-J shocks, significantly impaired contractility and intracellular Ca2+ dynamics. The adverse effects were greater after a 2-J shock compared with a 1-J shock. CONCLUSIONS: Higher defibrillation energy significantly impairs ventricular contractility at the myocyte level. Reductions in cardiomyocyte shortening and intracellular Ca2+ dynamics abnormalities were greater when higher energy shock was used.

High-energy defibrillation impairs myocyte contractility and intracellular calcium dynamics / G. Ristagno, T. Wang, W. Tang, S. Sun, C. Castillo, M. Weil. - In: CRITICAL CARE MEDICINE. - ISSN 0090-3493. - 36:11 suppl.(2008), pp. 422-427.

High-energy defibrillation impairs myocyte contractility and intracellular calcium dynamics

G. Ristagno
;
2008

Abstract

OBJECTIVES: We examined the effects of energy delivered with electrical defibrillation on myocyte contractility and intracellular Ca2+ dynamics. We hypothesized that increasing the defibrillation energy would produce correspondent reduction in myocyte contractility and intracellular Ca2+ dynamics. DESIGN: Randomized prospective study. SETTING: University-affiliated research laboratory. SUBJECTS: Ventricular myocytes from male Sprague-Dawley rat hearts. MATERIALS AND METHODS: Ventricular cardiomyocytes loaded with Fura-2/AM were placed in a chamber mounted on an inverted microscope and superfused with a buffer solution at 37 degrees C. The cells were field stimulated to contract and mechanical properties were assessed using a video-based edge-detection system. Intracellular Ca2+ dynamics were evaluated with a dual-excitation fluorescence photomultiplier system. Myocytes were then randomized to receive 1) a single 0.5-J biphasic shock; 2) a single 1-J biphasic shock; 3) a single 2-J biphasic shock; and 4) a control group without shock. After the shock, myocytes were paced for an additional 4 mins. RESULTS: A single 0.5-J shock did not have effects on contractility and intracellular Ca2+ dynamics. Higher energy shocks, i.e., 1- or 2-J shocks, significantly impaired contractility and intracellular Ca2+ dynamics. The adverse effects were greater after a 2-J shock compared with a 1-J shock. CONCLUSIONS: Higher defibrillation energy significantly impairs ventricular contractility at the myocyte level. Reductions in cardiomyocyte shortening and intracellular Ca2+ dynamics abnormalities were greater when higher energy shock was used.
myocyte; defibrillation; energy; contractility; intracellular calcium; energy
Settore MED/41 - Anestesiologia
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/620131
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