title: Characterization of cardiomyocyte excitation-contraction coupling in the FVB/N-C57BL/6 intercrossed "chocolate" brown mice.
abstract: Mice are extensively used for gene modification research and isolated cardiomyocytes are essential for evaluation of cardiac function without interference from non-myocyte contribution. This study was designed to characterize cardiomyocyte excitation-contraction coupling in FVB/N-C57BL/6 intercrossed brown mice. Mechanical and intracellular Ca(2+) properties were evaluated using an IonOptix softedge system including peak shortening (PS), time-to-PS (TPS), time-to-90% relengthening (TR(90)), maximal velocity of shortening and relengthening (+/- dL/dt), intracellular Ca(2+) rise and decay rate. Resting cell length was longer in age- and gender-matched C57BL/6 and brown mice compared to FVB strain. PS and +/- dL/dt were significantly lower in brown mice compared to FVB/N and C57BL/6 groups. TPS was shortened in C57BL/6 mice and TR(90) was prolonged in brown mice compared to other groups. Resting intracellular Ca(2+) level and single exponential intracellular Ca(2+) decay constant were comparable among all three mouse lines. Rise in intracellular Ca(2+) in response to electrical stimulus was higher in C57BL/6 mouse myocytes whereas bi-exponential intracellular Ca(2+) decay was faster in brown mice. Myocytes from all three groups exhibited similar fashion of reduction in PS in response to increased stimulus frequency. These data suggest that inherent differences in cardiomyocyte excitation-contraction coupling exist between strains, which may warrant caution when comparing data from these mouse lines.
authors.affiliation: Center for Cardiovascular Research and Alternative Medicine and Division of Pharmaceutical Sciences, University of Wyoming, Laramie, WY 82071, USA.
authors.forename: Qun
authors.initials: Q
authors.lastname: Li
authors.forename: Cindy X
authors.initials: CX
authors.lastname: Fang
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Nunn
authors.forename: Jesse
authors.initials: J
authors.lastname: Zhang
authors.forename: Karissa H
authors.initials: KH
authors.lastname: LaCour
authors.forename: Jun
authors.initials: J
authors.lastname: Ren
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D002465:Cell Movement; D004558:Electric Stimulation; D051379:Mice; D008815:Mice, Inbred Strains; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism*; D013045:Species Specificity
chemical_list: D002118:Calcium