Computational analysis of nitric oxide biotransport to red blood cell in the presence of free hemoglobin and NO donor
Introduction
Nitric oxide (NO) is generated in the endothelial cells as a response to shear stress from blood flow in the vasculature and acts a vasodilator (Ignarro et al., 1987, Moncada et al., 1991). The red blood cell (RBC) has emerged as a key player in the modulation of NO bioavailability (Owusu et al., 2012). Questions have been raised on the mechanisms of RBC–NO interaction and the transport of NO in physiologic and pathophysiologic conditions (Deonikar and Kavdia, 2010a). These issues have been raised for a number of reasons including the close proximity of RBCs to the endothelial cells, the high affinity of hemoglobin (Hb) for NO (Eich et al., 1996), and the probable pathway of NO escape from RBCs (Owusu et al., 2012). In addition, NO releasing drugs are being used in treatment of several pathological conditions including cancer, cardiovascular disease and wound healing (Baetta et al., 2013, Blecher et al., 2012, Cheng et al., 2012, Schade et al., 2011).
Endothelium-derived NO diffuses into the smooth muscle cell, activates soluble guanylate cyclase (sGC) that catalyzes conversion of GTP to cGMP and thus initiates vasodilation (Arnold et al., 1977). Majority of the NO enters the vascular lumen and is consumed by Hb in the RBCs (Butler et al., 1998, Gladwin et al., 2000, Joshi et al., 2002). RBC interaction with NO interaction leads to formation of methemoglobin and nitrate in oxygenated conditions and nitrosyl hemoglobin (HbNO) in deoxygenated conditions (Eich et al., 1996, Herold et al., 2001). On the other hand, RBCs can ‘store’ NO bioactivity in the form of S-nitrosohemoglobin (SNOHb) (Stamler et al., 1997) and deoxy-Hb can act as nitrite reductase to form NO (Gladwin et al., 2006, van Faassen et al., 2009). NO availability for vasodilation at the smooth muscle layer is determined by the transport barriers in the vascular lumen for NO transport from endothelium to the RBC–Hb or for transport of NO/active NO species from RBC to the vascular wall (Chen et al., 2007, Chen et al., 2008a, Deonikar and Kavdia, 2010b, Deonikar and Kavdia, 2013). NO consumption by RBC–Hb is much lower than that by extracellular free Hb due to the barriers for NO biotransport that include the extracellular free layer near the vessel wall (Deonikar and Kavdia, 2010a, Liao et al., 1999), extracellular diffusion (Liu et al., 2007), RBC membrane (Deonikar and Kavdia, 2013, Vaughn et al., 2001) and intracellular diffusion (Sakai et al., 2008).
In the absence of some of the transport barriers for free Hb, the presence of extracellular free Hb causes vasoconstriction (Doherty et al., 1998). Extracellular free Hb is also implicated in the hypertensive effects observed in pancreatitis and myocardial infarction (Winslow, 2013) as well as pulmonary hypertension seen in sickle cell disease, malaria and hemolytic anemia (Deonikar and Kavdia, 2012, Gladwin et al., 2010). Additionally, the lysis of blood or packed RBCs during storage is reported to cause post-transfusion toxicity (Donadee et al., 2011, Gladwin and Kim-Shapiro, 2009, Stapley et al., 2012). Theoretical analysis of hemolytic pathologies such as sickle cell disease (Deonikar and Kavdia, 2013) showed that even small amounts of extracellular free Hb led to insufficient NO concentrations at smooth muscle cell layer indicating insufficient vasodilation and subsequent hypertension.
In addition to its role in reducing NO bioavailability in physiological and pathophysiological conditions (Deonikar and Kavdia, 2012, Jeffers et al., 2006); extracellular free Hb is used in analyzing the various NO transport barriers in the vascular lumen and estimation of kinetic parameters for the NO–RBC interactions (Azarov et al., 2005, Liu et al., 2002, Vaughn et al., 2000). One such technique is an integrated experimental and theoretical analysis of competition for NO between extracellular free Hb and RBCs (‘competition experiments’). The ‘competition experiments’ using extracellular free Hb and well dispersed NO donor in the RBC suspension, (Vaughn et al., 2000, Vaughn et al., 2001) reported an ~ 1000–2000 times lower NO uptake by RBCs compared to that of free Hb owing to transport barriers from either the RBC membrane or intracellular diffusion. Moreover in these studies, NO–RBC interactions did not change significantly for hematocrit higher than 5%. Subsequent analyses of competition experiments implicated extracellular diffusion resistance as the main transport barrier for NO transport to RBC (Azarov et al., 2005, Liu et al., 2002) and the RBC membrane limits the NO transport effectively only under oxygenated conditions (Azarov et al., 2005).
Most of the ‘competition experiments’ to analyze NO–RBC reaction kinetics and the role of transport resistance were conducted at low hematocrit (≤~15%) (Liu et al., 1998, Liu et al., 2002, Vaughn et al., 2000, Vaughn et al., 2001). However, in a recent computational analysis, we have shown that the contribution from extracellular diffusion and RBC membrane resistance towards the overall transport resistance depended on the hematocrit and membrane permeability (Deonikar and Kavdia, 2013). These new insights indicate that the transport and kinetic characteristics of NO interactions with RBCs may be different at physiological range of hematocrit than those reported at a lower hematocrit.
To explore this possibility, an understanding of NO–RBC interactions in the presence of extracellular Hb at physiologic hematocrit is needed. For this purpose, we developed a computational model for the NO–RBC interactions for hematocrit ranging from 1 to 60% in the presence and absence of extracellular free Hb. This mathematical model also gives us a reliable platform to understand the NO–RBC interactions and NO distribution in the vascular lumen under pharmacological interventions where NO donors can be used to supplement NO activity.
Towards this end, we used two types of NO sources: 1) a constant NO source at a distance from the center of the RBC to simulate the endothelial NO transport to an RBC; and 2) homogenous NO source to simulate NO donor or NO delivery drug in the plasma layer surrounding each RBC. We quantified the NO availability inside the RBC, at the RBC membrane and at the outer edge of plasma. These results will help understand NO transport to and from RBCs and elucidate the role of RBCs in modulating the NO availability in vasculature in the presence of extracellular free Hb and an NO donor in the plasma layer. In addition, these results help us interpret results from the competition experiments.
Section snippets
Mathematical model
In order to simulate NO biotransport to an RBC, we developed a 1-dimensional model in spherical geometry based on an earlier RBC model (Deonikar and Kavdia, 2013). Briefly, the RBC core, the RBC membrane and the plasma layer surrounding the RBC are treated as concentric spheres as seen in Fig. 1. Extracellular free Hb is assumed to be uniformly dispersed in the plasma layer. We simulated two cases of NO biotransport in the present geometry. For Case 1, NO diffuses from outer boundary of the
Effect of extracellular free Hb and RBC membrane permeability on NO concentration profiles
To assess the effect of RBC membrane permeability in the presence of extracellular free Hb, we analyzed NO transport to RBC for permeability values of 0.0415, 0.4, 1 and 4 cm·s− 1. NO concentration at the edge of the plasma layer was 100 nM for these simulations. Figs. 2a and b shows the NO concentration profiles for 10% Hct and 45% Hct, respectively. The NO concentrations inside the RBC core were almost zero for all studied hematocrit, RBC membrane permeability and extracellular free Hb
Discussion
In this investigation, a 1-dimensional computational transport model of NO–RBC interactions is presented. The computational model analyzes the effects of extracellular free Hb on transport of NO to RBC at low and high hematocrit values for fixed distant NO source at the edge of the plasma layer and a uniformly distributed NO donor in the plasma. Understanding the mechanism of RBC interactions with NO in the presence of extracellular free Hb and quantification of NO supplementation in the form
Acknowledgments
This study is supported by NIH grants R01 HL084337.
References (57)
Nitric oxide scavenging by red blood cells as a function of hematocrit and oxygenation
J. Biol. Chem.
(2005)Nitric oxide-releasing nanoparticles accelerate wound healing in NOD-SCID mice
Nanomedicine
(2012)Diffusion of nitric oxide and scavenging by blood in the vasculature
Biochim. Biophys. Acta
(1998)- et al.
Conformation, co-operativity and ligand binding in human hemoglobin
J. Mol. Biol.
(1975) Diffusion and reaction of nitric oxide in suspension cell cultures
Biophys. J.
(1998)Nitric oxide from nitrite reduction by hemoglobin in the plasma and erythrocytes
Nitric Oxide
(2008)Effects of nitric oxide-releasing nonsteroidal anti-inflammatory drugs (NONO-NSAIDs) on melanoma cell adhesion
Toxicol. Appl. Pharmacol.
(2012)Nitric oxide and iron proteins
Biochim. Biophys. Acta
(1999)- et al.
A computational model for nitric oxide, nitrite and nitrate biotransport in the microcirculation: effect of reduced nitric oxide consumption by red blood cells and blood velocity
Microvasc. Res.
(2010) - et al.
Extracellular diffusion and permeability effects on NO–RBCs interactions using an experimental and theoretical model
Microvasc. Res.
(2010)
Contribution of membrane permeability and unstirred layer diffusion to nitric oxide–red blood cell interaction
J. Theor. Biol.
Oxidation of nitrogen oxides by bound dioxygen in hemoproteins
J. Inorg. Biochem.
Pulmonary hypertension and NO in sickle cell
Blood
Erythrocyte nitric oxide transport reduced by a submembrane cytoskeletal barrier
Biochim. Biophys. Acta
Nitric oxide red blood cell membrane permeability at high and low oxygen tension
Nitric Oxide
Computation of plasma hemoglobin nitric oxide scavenging in hemolytic anemias
Free Radic. Biol. Med.
Modeling of biopterin-dependent pathways of eNOS for nitric oxide and superoxide production
Free Radic. Biol. Med.
Endothelial NO and O2(−) production rates differentially regulate oxidative, nitroxidative, and nitrosative stress in the microcirculation
Free Radic. Biol. Med.
Wall shear stress differentially affects NO level in arterioles for volume expanders and Hb-based O2 carriers
Microvasc. Res.
Diffusion-limited reaction of free nitric oxide with erythrocytes
J. Biol. Chem.
Nitric oxide uptake by erythrocytes is primarily limited by extracellular diffusion not membrane resistance
J. Biol. Chem.
Estimation of nitric oxide concentration in blood for different rates of generation. Evidence that intravascular nitric oxide levels are too low to exert physiological effects
J. Biol. Chem.
Diffusion of nitric oxide in the aorta wall monitored in situ by porphyrinic microsensors
Biochem. Biophys. Res. Commun.
Encapsulation of concentrated hemoglobin solution in phospholipid vesicles retards the reaction with NO, but not CO, by intracellular diffusion barrier
J. Biol. Chem.
Erythrocytes possess an intrinsic barrier to nitric oxide consumption
J. Biol. Chem.
Erythrocyte consumption of nitric oxide: competition experiment and model analysis
Nitric Oxide
Respiration and Circulation
Nitric oxide activates guanylate cyclase and increases guanosine 3′:5′-cyclic monophosphate levels in various tissue preparations
Proc. Natl. Acad. Sci. U. S. A.
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