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Browsing by Subject "Cardiac output"
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Item Glucagon-Like Peptide 1 Receptor Activation Augments Cardiac Output and Improves Cardiac Efficiency in Obese Swine After Myocardial Infarction(American Diabetes Association, 2017-08) Sassoon, Daniel J.; Tune, Johnathan D.; Mather, Kieren J.; Noblet, Jillian N.; Eagleson, Mackenzie A.; Conteh, Abass M.; Sturek, Joshua T.; Goodwill, Adam G.; Cellular and Integrative Physiology, School of MedicineThis study tested the hypothesis that glucagon-like peptide 1 (GLP-1) therapies improve cardiac contractile function at rest and in response to adrenergic stimulation in obese swine after myocardial infarction. Obese Ossabaw swine were subjected to gradually developing regional coronary occlusion using an ameroid occluder placed around the left anterior descending coronary artery. Animals received subcutaneous injections of saline or liraglutide (0.005-0.015 mg/kg/day) for 30 days after ameroid placement. Cardiac performance was assessed at rest and in response to sympathomimetic challenge (dobutamine 0.3-10 μg/kg/min) using a left ventricular pressure/volume catheter. Liraglutide increased diastolic relaxation (dP/dt; Tau 1/2; Tau 1/e) during dobutamine stimulation (P < 0.01) despite having no influence on the magnitude of myocardial infarction. The slope of the end-systolic pressure volume relationship (i.e., contractility) increased with dobutamine after liraglutide (P < 0.001) but not saline administration (P = 0.63). Liraglutide enhanced the slope of the relationship between cardiac power and pressure volume area (i.e., cardiac efficiency) with dobutamine (P = 0.017). Hearts from animals treated with liraglutide demonstrated decreased β1-adrenoreceptor expression. These data support that GLP-1 agonism augments cardiac efficiency via attenuation of maladaptive sympathetic signaling in the setting of obesity and myocardial infarction.Item Measurement of cardiovascular function using a novel view-sharing PET reconstruction method and tracer kinetic analysis(Springer (Biomed Central Ltd.), 2016-12) Territo, Paul R.; Riley, Amanda A.; McCarthy, Brian P.; Hutchins, Gary D.; Department of Radiology and Imaging Sciences, School of MedicineRecent advancements in PET instrumentation have made the non-invasive assessment of cardiovascular function in small animals a reality. The majority of small animal PET systems use stationary detector gantries, thus affording high temporal resolution imaging of cardiac function. Systems designed to maximize spatial resolution and detection sensitivity employing rotating gantry designs are suboptimal when high temporal resolution imaging is needed. To overcome this limitation, the current work developed a novel view-sharing data analysis scheme suitable for dynamic cardiac PET imaging using (18)F-NaF as the tracer and tracer kinetic model analysis. This scheme was tested in a rat model of cardiovascular function where the relationship between direct transonic flow measures of cardiac output were highly correlated (f(x) = 1.0216x - 24.233, R = 0.9158, p < 0.001) with the new model. Similarly, derived measures of stroke volume were also highly correlated (f(x) = 0.9655x - 0.0428, R = 0.9453, p < 0.001) with the current approach. Administration of xylazine caused a statistically significant increase in stroke volume (0.32 ± 0.07 ml, p = 0.003, n = 4) and a significant decrease in both heart rate (-155 ± 7.1 beats/min, p < 0.001, n = 4) and cardiac output (-75.9 ± 23.0 ml/kg min, p = 0.01, n = 4). These findings suggest that the new sinogram binning and kinetic modeling methods produce reliable cardiac function measures suitable for longitudinal monitoring of cardiovascular function.