Browsing by Subject "Nitric Oxide"
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Item Effects of Nitric Oxide on Right Ventricular Metabolism and Coronary Blood Flow(2000-01-09) Setty, Srinath; H. Fred Downey; Patricia A. Gwirtz; James L. CaffreySetty, Srinath Varadaraj. Effects of Nitric Oxide on Right Ventricular Metabolism and Coronary Blood Flow Doctor of Philosophy (Biomedical Sciences), January, 9, 2001, 123 pp, 3 tables, 16 figures, references, 211 titles. Nitric oxide (NO) formed from L-arginine and released from vascular endothelium causes relaxation of vascular smooth muscle via a cGMP mechanism. However, the of NO as a regulator of coronary blood flow control is unclear. NO has been shown also to reduce oxygen consumption in various in-vitro preparations, but its effect on myocardial oxygen consumption (MVO2) in the left ventricle of the working heart is controversial. The effect of NO on MVO2 in the right ventricle (RV) is unknown. This investigation delineated the effects of NO on RV MVO2 during controlled systemic and coronary hemodynamic conditions. In open chest dogs, NO synthesis was blocked by intracoronary infusion of NO synthesis with Nω-nitro-L-arginine methyl ester (L-NAME, 150 μg/min). To avoid effects of NO synthesis blockade on right coronary blood flow (RCBF), which might have altered RV MVO2, experiments were conducted during adenosine-induced maximal right coronary vasodilation (n=12). RCBF, RV MVO2, and other variables were measured at baseline and at elevated right coronary perfusion pressures (RCP). Under these conditions, L-NAME significantly increased RV MVO2 at baseline and at elevated RCP (P [less than] 0.05 vs. untreated control condition). These results indicate that NO acts to retard RV oxidative metabolism. We further characterized the role of NO on RV MVO2 during increases in RV workload, estimated as a product of heart rate X RV peak systolic pressure X RV dP/dt. RV workload, RCBF, and RV MVO2 were increased by intracoronary norepinephrine infusions at baseline RCP (n=5). L-NAME significantly reduced RCBF (P [less than] 0.05 vs. untreated control condition), and RV MVO2 was significantly higher at any measured RV workload during L-NAME (P [less than] 0.05 vs. untreated control condition). These findings indicate that NO is an important component of RCBF control and that NO blunts norepinephrine-induced increase in RV MVO2. If NO reduced RV MVO2 it may be cardioprotective during moderate right coronary hypoperfusion. Thus, we sought to determine if in fact the RV MVO2 was reduced by NO during moderate right coronary hypoperfusion (n=9). RCP was reduced to 60 (n=5) and 40 mmHg (n=4), and RCBF and RV MVO2 fell as RCP was reduced. L-NAME significantly increased RV MVO2 at RCP of 60 and 40 mmHg (P [less than] 0.05 vs. untreated control condition), although RV workload was not altered. Since NO reduced RV MVO2 without compromising RV mechanical performance, RV oxygen utilization efficiency was enhanced. Taken together, these findings demonstrate that NO has a significant dampening effect on RV MVO2.Item IN VITRO MODEL FOR ALZHEIMER'S DISEASE DRUG DISCOVERY AND DEVELOPMENT FOCUSING ON OXIDATIVE-NITROSATIVE PATHWAYS(2013-04-12) Wesp, KrystynaPurpose: The Alzheimer's Association estimates that in the absence of disease-modifying treatments the total costs of care for individuals with Alzheimer's disease by all payers will soar from about $170 billion today to more than $1 trillion in 2050. The goal of our project is to develop an in vitro model for testing drugs capable of preventing or slowing the progression of Alzheimer's disease (AD). Previous studies have demonstrated that oxidative-nitrosative stress is an important trigger for Alzheimer's disease and other neurodegenerative disorders. Different nitrosative mechanisms have been proposed for the pathology of this disease, including 3-nitrotyrosination of proteins. Nitric oxide synthase (NOS) is an enzyme that forms nitric oxide. Though important for normal brain function, nitric oxide can react with superoxide formed under oxidative stress conditions to create peroxynitrite, a damaging chemical species that reacts with tyrosine residues to produce aberrant 3-nitrotyrosinated proteins. Recent research has shown certain receptors can modulate NOS activity, but further experiments need to be done to confirm the clinical effectiveness of targeting such receptors with selective drugs as a new therapeutic approach to treating AD and other brain injury states. Our current research is aimed at establishing an in vitro model containing all the necessary elements of the oxidative-nitrosative stress signaling pathway for future drug testing in a cellular model. Methods: Towards this end we have begun to identify relevant pathway elements in a number of cell lines utilizing polymerase chain reaction (PCR) techniques to amplify RNA coding for these elements. This was achieved by culturing cells, extracting purified RNA and reverse transcribing it into DNA and then amplifying the DNA with oligonucleotide primers designed to target specific pathway components (e.g. NOS). Amplified PCR products were confirmed by size determination utilizing agarose gel DNA electrophoresis and DNA sequencing of the correctly-sized bands. Results: Three cell lines, including a neuronal and a glial cell line, have been identified so far that contain a number of the critical elements required for the in vitro model. Conclusions: The identification of a viable in vitro model will allow for further experimentation that can determine the effectiveness of new drugs acting on specific receptor targets to modulate NOS activity and thereby slow the progression of diseases with a nitrosative stress component.