Browsing by Author "Gaidoo, Richard G."

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    The Effect of 17beta Estradiol on Glut1 Expression In The Right Ventricle Of Rats With Severe Pulmonary Hypertension
    (Office of the Vice Chancellor for Research, 2013-04-05) Taylor, Vanessa N.; Lahm, Tim; Cucci, Anthony; Petrache, Irina; Albrecht, Marjorie E.; Brown, Mary Beth; Chingombe, Tsungai J.; Gaidoo, Richard G.
    Pulmonary hypertension (PH) is a devastating disease that is characterized by a rise of blood pressure in the blood vessels of the lung. This puts significant strain on the right ventricle (RV) of the heart. If untreated, PH can lead to right heart failure and death. One of the hallmarks of right heart failure in PH is the development of cytoplasmic glycolysis in the cardiac muscle cells (myocytes) of the RV. This describes a compensatory process where glucose uptake into the mitochondria is inhibited, thereby leading to its conversion to lactate in the cytoplasm. Importantly, cytoplasmic glycolysis is associated with an increase in a protein called glucose transporter 1 (Glut 1). 17beta estradiol (E2) can ameliorate experimental PH, but its effects on RV glut 1 expression are not yet known. The aim of this project is to determine the RV expression of Glut 1 in a rat model of severe PH, and to investigate whether this is decreased by E2 treatment. We assessed Glut 1 via immunofluorescence staining in cryosections of RV tissue from control rats, untreated PH rats, and E2-treated PH rats. Cell nuclei were stained with DAPI (Diamidinophenyl-indole), cell membranes were stained with WGA (wheat germ agglutinin), and Glut1 was stained with a Glut1 antibody conjugated to a red immunofluorescent dye. Nuclei are stained blue; cell membranes are stained green. Glut 1 quantification occurs via visual inspection and determination of red staining via specific software (Metamorph). We were able to successfully establish the protocol for Glut1 staining. In pilot experiments, there was little Glut1 staining present in normal RVs, but we detected up-regulation of Glut 1 in the RV of animals with PH. Whether this is affected by E2 is currently under investigation.
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    Exercise Training Improves Cardiac and Skeletal Muscle Metabolism in Rats with Pulmonary Arterial Hypertension
    (Office of the Vice Chancellor for Research, 2013-04-05) Gaidoo, Richard G.; Crist, Jacob; Little, Nathaniel; Chingombe, Tsungai J.; Fisher, Amanda; Presson, Robert G.; Lahm, Tim; Petrache, Irina; Brown, Mary Beth
    In patients with pulmonary arterial hypertension (PAH), a shift from oxidative to glycolytic metabolism promotes right ventricular (RV) and skeletal muscle dysfunction that contributes to reduced exercise tolerance. As seen for other cardiopulmonary diseases, exercise training (ExT) may ameliorate this glycolytic switch in PAH and improve exercise capacity. The purpose of this research is to investigate ExT in a rat model of PAH on markers of glycolytic and oxidative metabolism in RV and skeletal muscle. Male Sprague-Dawley rats received monocrotaline (MCT, 40 mg/kg, s.q.) to induce PAH (n= 13), or saline, for healthy controls (n=5). After 2 wks, with MCT-induced PAH established, 6 wks of treadmill (TM) ExT was initiated for a subset of PAH animals (PAH-ExT, n= 6) and healthy controls (CON-ExT, n=3). ExT runs progressed up to 60 min at mild relative intensity, 50% of maximal aerobic capacity (VO2max). VO2max was assessed at baseline, in pre-training and post-training TM testing via analysis of expired gases. Abundance of Glut-1, a marker of glycolytic metabolism, was evaluated in cryosections of RV and soleus with immunofluorescent (IF) staining and quantification. Data are presented as mean±SE. MCT-ExT rats maintained aerobic capacity over 6 wks better than sedentary counterparts (MCT-SED)(VO2max= -134±109 vs. -521±129 ml/kg/hr, p=0.04) and was not different than CON-ExT (-201±31 ml/kg/hr, p=0.82). A lower abundance of Glut-1 was observed in both RV and soleus myocytes of PAH-ExT rats (MPI= 10.9 ±0.9 for RV; 13.7±0.8 for soleus) compared to PAH-SED rats (15.7±2.4, p=0.05, for RV; 17.4±1.4, p=0.04, for soleus) and was similar to CON-ExT rats (13.0±2.2, p=0.33, for RV; 9.0±2.3, p=0.26, for soleus), indicative of a shift toward greater dependency on oxidative metabolism. Exercise training attenuates functional decline following MCT administration in rats. Preservation of aerobic capacity may be explained by promotion of more efficient RV and skeletal muscle mitochondrial substrate utilization.