The role of nitric oxide and other gaseous mediators in cardiovascular disease models; emphasis on septic shock

THE ROLE OF NITRIC OXIDE AND OTHER GASEOUS MEDIATORS IN CARDIOVASCULAR DISEASE MODELS: EMPHASIS ON SEPTIC SHOCK FARHANA ANUAR NATIONAL UNIVERSITY OF SINGAPORE 2007 THE ROLE OF NITRIC OXIDE AND OTHER GASEOUS MEDIATORS IN CARDIOVASCULAR DISEASE MODELS: EMPHASIS ON SEPTIC SHOCK FARHANA ANUAR B.Sc.(Hons.), NUS A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY Acknowledgements I Acknowledgements I would like to thank both my supervisor and co-supervisor, Professor Philip K. Moore and A/Professor Madhav Bhatia for introducing me to the field of nitric oxide and septic shock and for allowing me the opportunity to undertake this PhD project. I am truly thankful for the continued guidance, supervision, patience and encouragement that both of you have given me throughout my whole project. I would also like to thank Abel, Baskar, Jia Ling, Mei Leng, Yibing, Yoke Ping, and Yusuf for their technical assistance and for making my stay in the cardiovascular lab an enjoyable and motivating place for me to work in. Also many thanks to the people working in the Department of Pharmacology, especially the cardiovascular lab, for their technical support and resources. And to my closest friends John, Pam, Nursha and Rangga, thank you for always being there for me and listening to my incessant complaints. Lastly, I am truly grateful to God for giving me an understanding and patient family that has provided me with their untiring encouragement. Because of you guys (Mum, Dad, Ismail, Salleh and Khalid) I did not give up writing this thesis. Not forgetting my beloved niece, Deanna, for always putting a smile on my face. This thesis I dedicate to all of you. II Abstract Abstract The effect of flurbiprofen (FLU) and its nitric oxide (NO) releasing derivative, nitroflurbiprofen (NOF), were evaluated in a caecal ligation puncture (CLP) model of septic shock in the rat. Caecal ligation puncture reduced mean arterial blood pressure accompanied by increases (P[...]... situation more akin to that seen clinically On the other hand, the LPS model results in a more direct, reproducible alteration in host responses to immune challenge Thus, for the second part of this project we decided to investigate the interaction between H2S and NO in the animal model of systemic inflammation viz E Coli LPS-induced endotoxic shock For these experiments, the NO-releasing non-steroidal... Nitric Oxide (NO) 2.1 Biosynthesis In mammalian cells, nitric oxide (NO) arises from the enzymatic oxidation of a terminal guanidino nitrogen of the amino acid, L-arginine (Furchgott & Zawadzki, 1980) (Figure 2-1) Per mole of arginine, this reaction consumes 1 mol of molecular O2 and 1.5 mol of NADPH, yielding 1 mol of NO and 1 mol of L-citrulline The responsible enzymes are a family of heme proteins... Caecal ligation and puncture (CLP)-induced septic shock model Induction of sepsis is intrinsically more challenging than inducing endotoxemia since the immune challenge is episodic in nature Some of the guidelines for progressive and lethal septic models outlined by Wichterman et al., (1980) in their review of septic modelling are stated as follows: (1) The animals should show clinical signs of sepsis... 8.4 FLU and NOF protect against septic shock in rats NOF reduces pro-inflammatory H2S formation in LPS rats 1400W reduces pro-inflammatory H2S formation in LPS rats Conclusions Bibliography 172 Introduction 1 Introduction Despite extensive studies over the last two decades, the precise role of nitric oxide (NO) in many cardiovascular disease (CVD) states remains unclear Numerous contradictory... Control) National Center for Health Statistics, sepsis is the leading cause of death in non-coronary intensive care unit patients, and the 10th most common cause of death overall in the United States alone for 2003 Similarly, according to Singapore’s Ministry of Health, sepsis is the 9th most common cause of death overall in Singapore for 2003 Despite numerous advances in our understanding of the pathophysiology... work in concert with other gaseous mediators such as hydrogen sulphide (H2S) to play an important physiological role in the control of blood vessel contractility and vascular perfusion (Zhao et al., 2003) Furthermore, a disordered biosynthesis of H2S (perhaps as a result of changes in the expression of cystathionine γ lyase (CSE) and/ or cystathionine β synthetase (CBS) which are enzymes that synthesizes... L-NAME (non-selective NOS inhibitor) and 1400W (selective iNOS inhibitor), were used in the LPS-induced endotoxic shock model, for the third part of the project (Chapter 7) In the following introductory chapters, we shall provide background information concerning, (i) the different animal models of producing septic/ endotoxic shock, (ii) the fundamental mechanisms leading to tissue and organ damage in sepsis,... heterogeneity of the clinical situations involved and the extreme complexity of the host response to overwhelming infection As such, the need to assess which animal model of inducing septic shock would best be utilized in our present project shall be discussed below Chapter 1: Sepsis, Septic Shock & Endotoxemia 7 1.2 Animal models Although often used synonymously, differences exist between the induction of sepsis... affecting the microcirculation include disturbed rheologic properties of circulating blood cells (Astiz et al., 1995) and the formation of microthromboses following disseminated intravascular coagulation and the plugging of vessels by activated platelets and leukocytes (Astiz et al., 1995; Hinshaw, 1996) All of these alterations contribute to impairment of the physiological mechanisms controlling microvascular... induction of sepsis and the induction of endotoxemia In general, for a particular animal model, sepsis induction results in a less predictable and less reproducible alteration in host responses to the immune challenge, although it is very similar to that seen clinically On the other hand, endotoxemia induction results in a more direct and reproducible alteration in host responses to the immune challenge . UNIVERSITY OF SINGAPORE 2007 THE ROLE OF NITRIC OXIDE AND OTHER GASEOUS MEDIATORS IN CARDIOVASCULAR DISEASE MODELS: EMPHASIS ON SEPTIC SHOCK FARHANA ANUAR B.Sc.(Hons.),. the heterogeneity of the clinical situations involved and the extreme complexity of the host response to overwhelming infection. As such, the need to assess which animal model of inducing septic. THE ROLE OF NITRIC OXIDE AND OTHER GASEOUS MEDIATORS IN CARDIOVASCULAR DISEASE MODELS: EMPHASIS ON SEPTIC SHOCK FARHANA ANUAR NATIONAL