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).

Project description:While blood vessels have muscular walls that undergo tonic contractions to alter vascular resistance and, thus, control blood flow, lymphatics at the level of the collecting vessels and higher have muscular walls capable of rapid phasic contractions that generate lymph flow in addition to tonic contractions that regulate lymph flow resistance. While the ability of lymphatics to undergo rapid phasic contractions has been known for several centuries, the biological elements governing this phenomenon remain unknown. In an attempt to gain insight into the structural and regulatory elements that give lymphatic vessels their unique contractile capabilities, we utilized two-color microarray analysis to compare the thoracic duct of the rat to the vena cava of the same donor animal. Total cellular RNA was isolated immediately following vessel isolation and amplified in the presence of amino allyl dUTP. The resulting modified aRNA was conjugated to either Cy3 or Cy5 dye prior to hybridization to a rat 5.7K oligonucleotide array. Analysis and filtering of the data obtained from the microarray image yielded several contractile and regulatory genes with altered expression in the thoracic duct relative to the vena cava. Further evaluation of the data obtained in this study may aid in illustrating the unique properties of the lymphatic vessel and its muscular wall. Keywords: Thoracic duct, lymphatics, microarray Four unique thoracic duct/vena cava sample pairs were individually analyzed via two-color microarray analysis yielding 4 biological replicates. To minimize dye bias, a dye balance design was utilized in which the orientation of dye assignment was alternated between vessel pairs (i.e. two thoracic duct samples were labeled with Cy3 and two were labeled with Cy5). Prior to analysis, the data from 2 of the replicates was transformed to accomodate the dye balance such that all thoracic duct data is interpreted as Cy5 and all vena cava data is interpreted as Cy3.

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Homo sapiens

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