Browsing by Author "Schultz, Kyle A."

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    Biphasic alterations in coronary smooth muscle Ca2+ regulation in a repeat cross-sectional study of coronary artery disease severity in metabolic syndrome
    (Elsevier, 2016-06) McKenney-Drake, Mikaela L.; Rodenbeck, Stacey D.; Owen, Meredith K.; Schultz, Kyle A.; Alloosh, Mouhamad; Tune, Johnathan D.; Sturek, Michael; Department of Cellular and Integrative Physiology, School of Medicine
    BACKGROUND AND AIMS: Coronary artery disease (CAD) is progressive, classified by stages of severity. Alterations in Ca(2+) regulation within coronary smooth muscle (CSM) cells in metabolic syndrome (MetS) have been observed, but there is a lack of data in relatively early (mild) and late (severe) stages of CAD. The current study examined alterations in CSM Ca(2+) regulation at several time points during CAD progression. METHODS: MetS was induced by feeding an excess calorie atherogenic diet for 6, 9, or 12 months and compared to age-matched lean controls. CAD was measured with intravascular ultrasound (IVUS). Intracellular Ca(2+) was assessed with fura-2. RESULTS: IVUS revealed that the extent of atherosclerotic CAD correlated with the duration on atherogenic diet. Fura-2 imaging of intracellular Ca(2+) in CSM cells revealed heightened Ca(2+) signaling at 9 months on diet, compared to 6 and 12 months, and to age-matched lean controls. Isolated coronary artery rings from swine fed for 9 months followed the same pattern, developing greater tension to depolarization, compared to 6 and 12 months (6 months = 1.8 ± 0.6 g, 9 months = 5.0 ± 1.0 g, 12 months = 0.7 ± 0.1 g). CSM in severe atherosclerotic plaques showed dampened Ca(2+) regulation and decreased proliferation compared to CSM from the wall. CONCLUSIONS: These CSM Ca(2+) regulation data from several time points in CAD progression and severity help to resolve the controversy regarding up-vs. down-regulation of CSM Ca(2+) regulation in previous reports. These data are consistent with the hypothesis that alterations in sarcoplasmic reticulum Ca(2+) contribute to progression of atherosclerotic CAD in MetS.
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    Metabolic Syndrome Abolishes Glucagon-Like Peptide 1 Receptor Agonist Stimulation of SERCA in Coronary Smooth Muscle
    (American Diabetes Association, 2015-09) Dineen, Stacey L.; McKenney, Mikaela L.; Bell, Lauren N.; Fullenkamp, Allison M.; Schultz, Kyle A.; Alloosh, Mouhamad; Chalasani, Naga; Sturek, Michael; Department of Cellular & Integrative Physiology, IU School of Medicine
    Metabolic syndrome (MetS) doubles the risk of adverse cardiovascular events. Glucagon-like peptide 1 (GLP-1) receptor agonists induce weight loss, increase insulin secretion, and improve glucose tolerance. Studies in healthy animals suggest cardioprotective properties of GLP-1 receptor agonists, perhaps partially mediated by improved sarco-endoplasmic reticulum Ca(2+) ATPase (SERCA) activity. We examined the acute effect of GLP-1 receptor agonists on coronary smooth muscle cells (CSM) enzymatically isolated from lean, healthy Ossabaw miniature swine. Intracellular Ca(2+) handling was interrogated with fura-2. The GLP-1 receptor agonist exenatide activated SERCA but did not alter other Ca(2+) transporters. Further, we tested the hypothesis that chronic, in vivo treatment with GLP-1 receptor agonist AC3174 would attenuate coronary artery disease (CAD) in swine with MetS. MetS was induced in 20 swine by 6 months' feeding of a hypercaloric, atherogenic diet. Swine were then randomized (n = 10/group) into placebo or AC3174 treatment groups and continued the diet for an additional 6 months. AC3174 treatment attenuated weight gain, increased insulin secretion, and improved glucose tolerance. Intravascular ultrasound and histology showed no effect of AC3174 on CAD. MetS abolished SERCA activation by GLP-1 receptor agonists. We conclude that MetS confers vascular resistance to GLP-1 receptor agonists, partially through impaired cellular signaling steps involving SERCA.
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    Repeat cross-sectional data on the progression of the metabolic syndrome in Ossabaw miniature swine
    (Elsevier, 2016-04-13) McKenney-Drake, Mikaela L.; Rodenbeck, Stacey D.; Owen, Meredith K.; Schultz, Kyle A.; Alloosh, Mouhamad; Tune, Johnathan D.; Sturek, Michael; Department of Cellular & Integrative Physiology, IU School of Medicine
    Ossabaw miniature swine were fed an excess calorie, atherogenic diet for 6, 9, or 12 months. Increased body weight, hypertension, and increased plasma cholesterol and triglycerides are described in Table 1. For more detailed interpretations and conclusions about the data, see our associated research study, "Biphasic alterations in coronary smooth muscle Ca(2+) regulation during coronary artery disease progression in metabolic syndrome" McKenney-Drake, et al.