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Myocardial contractile response to physiological stress improves with high saturated fat feeding in heart failure

ABSTRACT: 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).

ORGANISM(S): Rattus norvegicus

SUBMITTER: Molly Bray

PROVIDER: E-GEOD-21021 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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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:We studied the effect of dietary fat type, varying in polyunsaturated/saturated fatty acid ratio's (P/S) on development of metabolic syndrome. C57Bl/6J mice were fed purified high-fat diets (45E% fat) containing palm oil (HF-PO; P/S 0.4), olive oil (HF-OO; P/S 1.1) or safflower oil (HF-SO; P/S 7.8) for 8 weeks. A low-fat palm oil diet (LF-PO; 10E% fat) was used as a reference. Additionally, we analyzed diet-induced changes in gut microbiota composition and mucosal gene expression. The HF-PO diet induced a higher body weight gain and liver triglyceride content compared to the HF-OO, HF-SO or LF-PO diet. In the intestine, the HF-PO diet reduced microbial diversity and increased the Firmicutes/Bacteroidetes ratio. Although this fits a typical obesity profile, our data clearly indicate that an overflow of the HF-PO diet to the distal intestine, rather than obesity itself, is the main trigger for these gut microbiota changes. A HF-PO diet-induced elevation of lipid metabolism-related genes in the distal small intestine confirmed the overflow of palm oil to the distal intestine. Some of these lipid metabolism-related genes were previously already associated with the metabolic syndrome. In conclusion, our data indicate that saturated fat (HF-PO) has a more stimulatory effect on weight gain and hepatic lipid accumulation than unsaturated fat (HF-OO and HF-SO). The overflow of fat to the distal intestine on the HF-PO diet induced changes in gut microbiota composition and mucosal gene expression. We speculate that both are directly or indirectly contributive to the saturated fat-induced development of obesity and hepatic steatosis. Keywords: Diet intervention study Nine-week-old C57Bl/6J mice were fed a low-fat diet (LF-PO) and three different types of high-fat diet, based on palm oil (HF-PO; P/S1.0), olive oil (HF-OO; P/S4.6) and safflower oil (HF-SO; P/S10.1) for 8 weeks. Body weight was recorded weekly and after 7 weeks of diet intervention an oral glucose tolerance test was performed. After 2 weeks of diet intervention, 6 mice per high-fat diet group were anaesthetized with a mixture of isofluorane (1.5%), nitrous oxide (70%) and oxygen (30%) and the small intestines were excised. Adhering fat and pancreatic tissue were carefully removed. The small intestines were divided in three equal parts along the proximal to distal axis (SI 1, SI 2 and SI 3) and microarray analysis was performed on mucosal scrapings.

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Myocardial contractile response to physiological stress improves with high saturated fat feeding in heart failure

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