Transgenic rabbit model for human troponin I-based hypertrophic cardiomyopathy. Circulation 2005 May 10;111(18):2330-8
Date
05/04/2005Pubmed ID
15867176Pubmed Central ID
PMC1314982DOI
10.1161/01.CIR.0000164234.24957.75Scopus ID
2-s2.0-20844459661 (requires institutional sign-in at Scopus site) 64 CitationsAbstract
BACKGROUND: Transgenic and gene-targeted models have focused on the mouse. Fundamental differences between the mouse and human exist in Ca2+ handling during contraction/relaxation and in alterations in Ca2+ flux during heart failure, with the rabbit more accurately reflecting the human system.
METHODS AND RESULTS: Cardiac troponin I (cTnI) mutations can cause familial hypertrophic cardiomyopathy. An inhibitory domain mutation, arginine146-->glycine (cTnI(146Gly)), was modeled with the use of transgenic expression in the rabbit ventricle. cTnI(146Gly) levels >40% of total cTnI were perinatally lethal, whereas replacement levels of 15% to 25% were well tolerated. cTnI(146Gly) expression led to a leftward shift in the force-pCa2+ curves with cardiomyocyte disarray, fibrosis, and altered connexin43 organization. In isolated cTnI(146Gly) myocytes, twitch relaxation amplitudes were smaller than in normal cells, but [Ca]i transients and sarcoplasmic reticulum Ca2+ load were not different. Detrended fluctuation analysis of the QT(max) intervals was used to evaluate the cardiac repolarization phase and showed a significantly higher scaling exponent in the transgenic animals.
CONCLUSIONS: Expression of modest amounts of cTnI(146Gly) led to subtle defects without severely affecting cardiac function. Aberrant connexin organization, subtle morphological deficits, and an altered fractal pattern of the repolarization phase of transgenic rabbits, in the absence of entropy or other ECG abnormalities, may indicate an early developing pathology before the onset of more obvious repolarization abnormalities or major alterations in cardiac mechanics.
Author List
Sanbe A, James J, Tuzcu V, Nas S, Martin L, Gulick J, Osinska H, Sakthivel S, Klevitsky R, Ginsburg KS, Bers DM, Zinman B, Lakatta EG, Robbins JMESH terms used to index this publication - Major topics in bold
AnimalsAnimals, Genetically Modified
Calcium
Cardiomegaly
Cardiomyopathy, Hypertrophic, Familial
Connexin 43
Disease Models, Animal
Electrocardiography
Fibrosis
Heart Function Tests
Heart Ventricles
Humans
Mutation, Missense
Myocytes, Cardiac
Phenotype
Rabbits
Transgenes
Troponin I