Project description:Full Title: Transition from Compensated Hypertrophy to Systolic Heart Failure in the Spontaneously Hypertensive Rat: Structure, Function, and Transcript Analysis Gene expression changes and left ventricular remodeling associated with the transition to systolic heart failure (HF) were determined in the spontaneously hypertensive rat (SHR). By combining transcriptomics of left ventricles from six SHR with HF with changes in function and structure we aimed to better understand the molecular events underlying the onset of systolic HF compared to six age-matched, SHR with compensated hypertrophy. Left ventricle (LV) ejection fraction was depressed (82Â±4 to 52Â±3 %) in compensated vs. failing animals.Â Systolic blood pressure decreased and LV end-diastolic and systolic volume increased with HF.Â Failing SHR hearts also demonstrated increases in left and right ventricular mass relative to non-failing SHRs.Â Â LV papillary muscle force development and shortening velocity decreased, Î²-adrenergic responsiveness was depressed, myocardial stiffness and myocardial fibrosis increased with HF relative to non-failing animals. Initial micro-array analysis revealed that 1,431 transcripts were differentially expressed with HF compared to non-failing SHR (p<0.05). Of the identified transcripts, lipopolysaccharide binding protein, the most highly expressed transcript with HF, was negatively correlated to myocardial force while elevated expression of the collagen cross-linking enzyme lysyl oxidase correlated positively with muscle stiffness. Besides these individual transcripts, gene set enrichment analysis (GSEA) identified multiple enriched pathways with HF, most prominent of the altered signaling pathways involved TGF-Î² and insulin signaling. GESA analysis additionally identified altered gene sets involving inflammation, oxidative stress, cell degradation and cell death, among others (all p<0.01). In contrast to diastolic HF where few transcripts are reported to be altered, our data indicate multiple genes and pathways involved in a variety of biological processes characterize the onset of systolic HF, consistent with many functional and structural changes present in the failing hypertensive heart. Comprehensive gene expression profiling of heart failure Rat model vs control.

Project description:Impaired myocardial contractile function is a hallmark of heart failure (HF) which may present under resting conditions and/or during physiological stress. Previous studies reported that high fat feeding in HF is associated with improved myocardial contractile function at baseline. Our goal was to determine whether myocardial function is compromised in response to physiological stress and to evaluate the global gene expression profile of rats fed high dietary fat following infarction. Male Wistar rats underwent ligation or sham surgery and were fed normal (10% kcal fat) (SHAM+NC, HF+NC) or high fat (60% kcal saturated fat) (SHAM+SAT, HF+SAT) for 8 weeks. Myocardial contractile function was assessed using a Millar pressure-volume (PV) conductance catheter at baseline, during inferior vena caval occlusions and dobutamine (DOB) stress. Steady state indices of systolic function, left ventricular (LV)+dP/dtmax, stroke work and maximal power were increased in HF+SAT vs HF+NC; HF+NC were reduced vs SHAM+NC. Preload-recruitable measures of contractility [end systolic PV relationship, maximal elastance, preload recruitable SW and peak+dP/dtmax to end diastolic volume] were decreased in HF+NC but not HF+SAT. β-adrenergic responsiveness (delta-LV+dP/dtmax and delta-cardiac output DOB 0-10 µg•kg-1•min-1) was reduced in HF, but high fat feeding did not further impact contractile reserve in HF. Contractile reserve was reduced by high fat in SHAM+SAT. Microarray gene expression analysis reveals the majority of significantly altered pathways identified to contain multiple gene targets correspond to cell signaling pathways and energy metabolism. These findings suggest that high saturated fat improves myocardial function at rest and during physiological stress in infarcted hearts, but may negatively impact contractile reserve under non-pathological conditions. Furthermore, high fat feeding-induced alterations in gene expression related to energy metabolism and specific signaling pathways reveal promising targets through which high saturated fat potentially mediates cardioprotection in heart failure/LV dysfunction.

Project description:Impaired myocardial contractile function is a hallmark of heart failure (HF) which may present under resting conditions and/or during physiological stress. Previous studies reported that high fat feeding in HF is associated with improved myocardial contractile function at baseline. Our goal was to determine whether myocardial function is compromised in response to physiological stress and to evaluate the global gene expression profile of rats fed high dietary fat following infarction. Male Wistar rats underwent ligation or sham surgery and were fed normal (10% kcal fat) (SHAM+NC, HF+NC) or high fat (60% kcal saturated fat) (SHAM+SAT, HF+SAT) for 8 weeks. Myocardial contractile function was assessed using a Millar pressure-volume (PV) conductance catheter at baseline, during inferior vena caval occlusions and dobutamine (DOB) stress. Steady state indices of systolic function, left ventricular (LV)+dP/dtmax, stroke work and maximal power were increased in HF+SAT vs HF+NC; HF+NC were reduced vs SHAM+NC. Preload-recruitable measures of contractility [end systolic PV relationship, maximal elastance, preload recruitable SW and peak+dP/dtmax to end diastolic volume] were decreased in HF+NC but not HF+SAT. β-adrenergic responsiveness (delta-LV+dP/dtmax and delta-cardiac output DOB 0-10 µg•kg-1•min-1) was reduced in HF, but high fat feeding did not further impact contractile reserve in HF. Contractile reserve was reduced by high fat in SHAM+SAT. Microarray gene expression analysis reveals the majority of significantly altered pathways identified to contain multiple gene targets correspond to cell signaling pathways and energy metabolism. These findings suggest that high saturated fat improves myocardial function at rest and during physiological stress in infarcted hearts, but may negatively impact contractile reserve under non-pathological conditions. Furthermore, high fat feeding-induced alterations in gene expression related to energy metabolism and specific signaling pathways reveal promising targets through which high saturated fat potentially mediates cardioprotection in heart failure/LV dysfunction. Comparison of gene expression in heart failure or sham surgery hearts exposed to saturated or normal diets. Male Wistar rats (300-350g) were maintained on a reverse light-dark cycle and all procedures were done 3-6 hours into the dark phase cycle to synchronize with the normal active state of the rodents. Rats were randomly assigned to receive either a sham-operation (SH) or coronary ligation to induce cardiac dysfunction (HF). Heart failure was induced by ligating the left main coronary artery. Following surgery, rats were immediately fed either a normal rodent chow (NC) or a high saturated fat chow (SAT) with 60% caloric content derived from fat (25% palmitic, 33% stearic, 33% oleic acid, Research Diets).

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Transition from Compensated Hypertrophy to Systolic Heart Failure in the Spontaneously Hypertensive Rat

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