== A total of 90 animals were anesthetized by intraperitoneal injection of 30 mg ketamine along with 1,000 U heparin and euthanized by decapitation after a negative response to a noxious stimulus. as BN hearts in mitochondrial and myocardial function and viability compared with SS hearts. These findings not only link myocardial and mitochondrial protection in a genetic model but also suggest that genetic information on rat chromosome 6 is critical for mitochondrial preservation and IR tolerance. Keywords:Brown Norway, Dahl salt sensitive, SS6BN, myocardium cardiovascular disease continuesto be the most common cause of death, accounting for nearly 40% of the deaths in the developed world (13). In the United LX-4211 States alone, one in every six deaths is caused by coronary artery disease (CAD) (25). Various behavioral and metabolic risk factors can be modified by treatment or prevention. Although each of these factors may be in part genetically determined, family history is an independent predisposing factor suggesting that additional susceptibility genes exist (6). Greater knowledge of the relationship between genetic determinants and outcome after myocardial ischemia-reperfusion (IR) injury would help to identify target genes and pathways that convey higher tolerance to IR. Interestingly, profound differences in individual IR tolerance have been found among (27) and even within different species. For example, Brown Norway (BN) rats exhibit more resistance to myocardial IR injury than does the Dahl salt-sensitive (SS) strain (3). Moreover, introgression of BN chromosome 6 into an SS background (SS6BN) conferred significant cardioprotection (17). In other words, one or more genes on chromosome 6 with or RGS17 without linkage to other chromosomes may be responsible for higher IR tolerance. Furthermore, since human studies have implicated genes on LX-4211 chromosome 14 to increase the risk for myocardial infarction (MI) (6) and human chromosome 14 is homologous to rat LX-4211 chromosome 6, the consomic SS6BNstrain constitutes a unique and promising model to study the genetic basis of cardioprotection. To date, studies have focused primarily on differences in the cardiac functional phenotype between BN, SS6BN, and SS strains undergoing IR. The impact of BN chromosome 6 substitution on mitochondrial function is unknown. Altered mitochondrial function has been demonstrated to be both a trigger and effector of cardioprotection (7,8,22). Therefore, the objective of our study was to link mitochondrial preservation with genome-dependent endogenous cardioprotection in BN, SS6BN, and SS rats. == MATERIALS AND METHODS == Our methods have been described in detail previously (1,12,2123). Unless otherwise indicated, all drugs were purchased from Sigma (St. Louis, MO). All indicated concentrations are final. == == == Animals. == All investigations conformed to theGuide for the Care and Use of Laboratory Animals(Institute for Laboratory Animal Research, National Academy of Sciences, 8th edition, 2011) and were approved by the Institutional Animal Care and Use Committee (AUA 1147, Medical College of Wisconsin, and ACORP 7435-1, VA Medical Center, Milwaukee, WI). The use of BN and SS rat strains as animal models to study cardiovascular disease processes is well established (10,17,28). The SS6BNpanel was constructed by crossing parental BN and SS to generate a heterozygous Fl population; a male F1 is then backcrossed with a female SS to generate N2 rats that are subsequently backcrossed for up to 10 generations to yield offspring with an isogenic SS background for all but chromosome 6 (10). Because the N2 is generated from an SS mother, the mitochondrial genome is derived from the SS strain. To avoid the confounding influence of sex (19) or increasing phenotypical LX-4211 baseline differences developed over time, we used only 8 wk old normoxic male BN/NHsdMcwi, SS6BN, and SS/JrHsdMcwi rats on a 0.4% NaCl diet. == Langendorff heart preparation. == A total of 90 animals were anesthetized by intraperitoneal injection of 30 mg ketamine along with 1,000 U heparin and euthanized by decapitation after a negative response to a noxious stimulus. After thoracotomy, the LX-4211 aorta was cannulated distal to.