Browsing by Author "Warne, Cooper"
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Item Cardiovascular Response to Endotoxin-Mediated Sepsis: A Dose-Response Study(2022) Aguirre, David Salinas; Martinez, Richard; Warne, Cooper; Mallet, Robert T.; Dick, Gregory; Tune, Johnathan; Hodge, LisaPurpose: Our long-term goal is to advance our understanding and treatment of sepsis, a potentially life-threatening condition that occurs when the response to infection causes tissue and organ damage. Sepsis can be caused by lipopolysaccharide (LPS), a major component of the outer membrane of Gram-negative bacteria. We used a swine model of LPS-induced sepsis to study the impact of the lymphatic and immune systems on the disease progression. Our first experiments were aimed at determining the optimal dose of Escherichia coli LPS in order to study the effect of sepsis on the cardiovascular system. We hypothesized that 2-hour intravenous infusions of 1- 50 µg/kg LPS would reveal dose- and time-dependent changes in hemodynamic parameters that are consistent with sepsis. Methods: Yorkshire pigs (61 ± 4 kg, n = 4, 2 male) were sedated, intubated, and ventilated. Femoral artery and venous lines were placed to allow measurement of blood pressure, infusion of LPS, and blood gas sampling. A thoracotomy was performed in order to secure a Transonic flow probe around the left anterior descending coronary artery and to insert a sampling catheter in the anterior cardiac vein. A dose of LPS (1, 5, 25, and 50 µg/kg) was given to each pig over 2 hours. Blood samples were collected immediately before LPS infusion and for every 30 minutes during and after LPS infusion for blood gas measurements. Vital signs were recorded as the animals developed sepsis. Results: Only the pig given the lowest dose of LPS (1 µg/kg) survived the full 6 hours (mean survival time in remaining 3 pigs was 180 ± 30 min). At 150 min, a ≈55% decrease in mean arterial pressure was observed (107 ± 4 to 48 ± 13 mmHg), resulting in a ≈60% increase in heart rate (91 ± 9 to 146 ± 14 beats/min). Coronary blood flow and myocardial oxygen consumption decreased ≈28% (0.53 ± 0.06 to 0.38 ± 0.02 ml/min/g) and ≈33% (60 ± 6 to 44 ± 2 µl/min/g), respectively. Ventricular fibrillation was the cause of death in the 3 non-surviving pigs. Conclusion: A dose of 1 µg/kg appears to be an optimal dose for future studies, as this dose was survivable in the desired time frame, while causing hypotension and tachycardia. In future studies, this model will allow us to study the effect of novel therapeutics during acute sepsis.Item Cytokine Response in an Endotoxin-Mediated Sepsis Model(2022) Martinez, Richard; Aguirre, David Salinas; Warne, Cooper; Dick, Gregory; Mallet, Robert T.; Tune, Johnathan; Hodge, LisaPurpose: Sepsis is a life-threatening condition that develops secondary to infection and can manifest acute organ dysfunction due to the body's overactive systemic response. Sepsis affects approximately 1.7 million US adults and claims 270,000 lives as a result. The long-term goal of our project is to gain a better understanding of the roles of the lymphatic and immune systems in the progression of sepsis. The purpose of this study is to collect pilot data using a translational swine model of endotoxin-mediated sepsis. We chose a swine model because it closely mimics how sepsis progresses in humans. Sepsis was induced by infusion of lipopolysaccharide (LPS) from Escherichia coli. LPS was chosen because it is a key mediator in the activation of the immune system and the development of sepsis. We hypothesized that the administration of LPS would increase the concertation of the proinflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-?) in a dose-dependent manner over time. Methods: Yorkshire pigs (61 � 4 kg, n = 4, 2 male) were sedated, intubated, and ventilated. Thoracotomy was performed under anesthesia to record flow data and sample cardiac blood for use in another study. Femoral artery and venous lines were placed to allow measurement of blood pressure and infusion of LPS. Specifically, LPS was prepared at 1, 5, 25, or 50 ?g/kg (pig body weight) in sterile saline. LPS was infused into anesthetized pigs over a 2-hour period. Blood samples were collected immediately prior to LPS administration and at 30 min intervals during 2 hours of LPS infusion up to 4 hours following LPS infusion. The plasma was analyzed via enzyme-linked immunosorbent immunoassay (ELISA) for the concentrations of IL-6 and TNF-? using commercially available kits. Results: As hypothesized, the infusion of LPS increased the concentration of the inflammatory mediators IL-6 and TNF-? over time compared to pre-LPS infusion. Specifically, the greatest increase in IL-6 was seen at 180 minutes in both the 50 and 25 ?g/kg LPS infused pigs. TNF-? concentration peaked between 30 to 90 minutes during LPS infusion in both the 50 and 25 ?g/kg LPS infused pigs. The lower doses of 1 and 5 ?g/kg LPS produced little to no IL-6 or TNF-?. Furthermore, we discovered that the pigs who received 50 or 25 ?g/kg of LPS died from septic shock within 180 minutes of LPS infusion, whereas the pigs that received 1or 5 ?g/kg of LPS survived longer. Conclusion: In this study, we identified the impact of increasing the doses of LPS on the production of IL-6 and TNF-? in swine. Our preliminary results suggest a dose range of 10-20 ?g/kg of LPS may be ideal to study the inflammatory response in this model. The acquisition of these data are essential to pursue our long-term research objective, which is to identify the role of the lymphatic and immune systems during sepsis.Item Effect of Sigma-1 Receptor Activation on Renal Injury and Hypertension in Female Mice with Lupus(2023) Dinh, Viet; Chaudhari, Sarika; Young-Stubbs, Cassandra M.; Shimoura, Caroline; Tucker, Selina; Essajee, Salman; Warne, Cooper; Luedtke, Robert R.; Mathis, Keisa W.Systemic lupus erythematosus (SLE) is a female-dominant autoimmune disease with prominent renal injury and hypertension, contributing to its morbidity and mortality. Novel therapies to reduce these detrimental outcomes could be beneficial to SLE patients. The sigma-1 receptor (S1R) is a cytoprotective ligand-regulated chaperone protein that decreases protein aggregation, cellular stress, and cell death, thus preventing tissue injury. S1R activation with pharmacological ligands enhances cytoprotection in autoimmune diseases like multiple sclerosis and Huntington’s disease; however, the efficacy of S1R agonists in SLE is unknown. We hypothesize that S1R activation via the agonist LS-1-127 will reduce renal injury and halt the progression of hypertension in SLE mice. Female SLE (NZBWF1) and control (NZW) mice were weighed and urine collected via metabolic cages weekly starting at 30 weeks of age. Albuminuria was measured via dipsticks. At 33 weeks of age, SLE and control mice were treated with LS-1-127 (10 mg/kg IP) or equal volume of vehicle (10% DMSO; IP) three times a week for two weeks. At 35 weeks, mean arterial pressure (MAP) was measured in conscious mice using indwelling carotid catheters for two consecutive days and then mice were euthanized. Wire myography was used to assess potassium chloride (KCl)-induced contraction and acetylcholine (ACh)-induced relaxation in excised aorta. Markers of renal injury – urinary neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), and creatinine – as well as plasma double-stranded (ds)DNA autoantibodies were measured by ELISA. Albuminuria was present in 44.4% (4 of 9) of SLE mice and no controls. LS-1-127 did not improve albuminuria in SLE mice (50%; 3 of 6). NGAL:creatinine ratio (ng/mg) was higher in SLE mice compared to controls (327.3 ± 119.8 vs 63.2 ± 4.3 ng/mg; n=9–12; P=0.0007). LS-1-127 did not significantly alter NGAL:creatinine ratio in SLE mice (484.3 ± 209.0; n=6) or controls (71.7 ± 5.2; n=10). KIM1:creatinine ratio (ng/mg) did not differ between groups. dsDNA autoantibodies were higher in SLE mice compared to controls (6.9e5 ± 1.1e5 vs. 1.4e5 ± 3.1e4 U/mL; n=9–10; P<0.0001). LS-1-127 did not significantly alter dsDNA autoantibodies in SLE mice (7.1e5 ± 1.2e5; n=6) or controls (1.5e5 ± 4.0e4; n=10). MAP was higher in SLE mice compared to controls (146 ± 4 vs. 123 ± 3 mmHg; n=9–10; P <0.0001). LS-1-127 did not significantly alter MAP in SLE mice (150 ± 8; n=6) or controls (124 ± 2; n=10). KCl-induced aortic contraction was similar in SLE and controls (21 ± 7 vs. 25 ± 4 mM, n=3–4). Sensitivity to KCl after LS-1-127 treatment was 11 ± 3 and 21 ± 2 mM in SLE and controls (n=2–4). ACh-induced aortic relaxation did not differ between groups. In conclusion, two weeks of S1R activation with LS-1-127 did not significantly alter markers of renal injury, autoimmunity, blood pressure, or vascular reactivity in female SLE mice with advanced disease. Further inquiry into the effect of LS-1-127 on the expression of renal proinflammatory cytokines will be conducted. S1R activation at different stages of SLE disease progression also warrants future investigation.Item The effects of esmolol on the control of coronary blood flow and myocardial oxygen supply-demand balance in sepsis(2024-03-21) Digilio, Michaela; Warne, Cooper; Heard, Michael; Tucker, Selina; Essajee, Sal; Bradford, Ni' Ja D.; Hodge, Lisa; Tune, Johnathan; Dick, GregoryPurpose: Sepsis is an acute organ dysfunction secondary to infection that results in tachycardia, tachypnea, fever, decreased blood pressure, and lactic acidosis. This results in an overall myocardial oxygen supply-demand imbalance leading to cardiac dysfunction and ultimately death. The current treatment for sepsis is antibiotic therapy, vasopressors, and fluid therapy. However, this regimen does not address the tachycardia that leads to cardiovascular decompensation. Beta-blocker therapy addresses this myocardial oxygen supply-demand imbalance and is expected to promote survival in sepsis. We hypothesize that treatment with beta-blocker therapy during acute sepsis will address the myocardial oxygen supply-demand imbalance to maintain coronary perfusion pressure, improve myocardial oxygen delivery, and promote survival. Methods: Female and male Yorkshire pigs were used as the animal model for this project. Pigs were anesthetized, intubated, and a rectal thermometer and oximeter were placed. Catheters placed in ear vein, great cardiac vein, femoral artery, and bilateral femoral veins. Pressure transducer placed in the femoral artery. A transonic flow transducer placed around the left anterior descending artery. After instrumentation, baseline values were collected. Then, infusion with Escherichia coli lipopolysaccharide (LPS) at 10 µg/kg over the course of 2 hours was used to induce sepsis. LPS was infused via the femoral vein at a rate of 0.5mL/min. After 2 hours, intervention began depending on the treatment group. Intervention lasted 4 hours. Experiment groups included Sham (without LPS, fluids, norepinephrine (NE), or esmolol), Control (with LPS, no fluids, NE, or esmolol), Standard (with LPS, fluids, and NE), and Experimental (with LPS, fluids, NE and esmolol). Doses: LPS 10 µg/kg, esmolol escalating from 100mg/hr, and NE escalating from 0.4 µg/kg/min. Goals during the intervention included keeping the mean arterial pressure (MAP) above 65mmHg and heart rate below 100. Results: All control pigs died during the 4-hour follow-up. 1 out of 3 standard treatment pigs survived. All esmolol-treated pigs survived. The esmolol group had better MAP, coronary blood flow, myocardial oxygen delivery, and oxygen extraction than the standard treatment group. Conclusion: Esmolol improves survival, coronary perfusion pressure, and myocardial oxygen delivery. This data provides support for our hypothesis and the clinical use of esmolol in sepsis.Item Effects of the thromboxane receptor antagonist S18886 in the porcine coronary circulation(2023) Tucker, Selina M.; Warne, Cooper; Essajee, Salman; Goulopoulou, Styliani; Dick, Gregory; Tune, JohnathanThromboxane A2 (TxA2) is a potent coronary vasoconstrictor that has been implicated in promoting decreases in myocardial perfusion in a variety of (patho)-physiologic conditions. S18886 is a promising orally-active TxA2 receptor antagonist currently approved for investigational clinical use. However, the coronary vascular effects of S18886 are unknown and its specificity and affinity for the thromboxane receptor in the coronary circulation remain unclear. We tested the hypothesis that administration of S18886 dose-dependently attenuates coronary vasoconstriction to the TxA2 mimetic U46619 without influencing coronary responses to prostaglandin F2α, acetylcholine, or smooth muscle depolarization (K+). Experiments to test this hypothesis were performed in male (n = 5) and female (n = 6) domestic swine. Hearts were excised and the left circumflex coronary artery isolated, cleaned of periadventitial fat, and cut into 3 mm rings. Isometric tension of coronary artery rings was measured in response to log order increments of U46619 (1 nM to 1 µM) with and without S18886 (0.1-100 nM). Similar isometric studies were conducted with prostaglandin F2α (10 nM-10 µM), acetylcholine (0.1-10 µM), and KCl (5-90 mM). U46619 induced concentration dependent increases in tension development of isolated coronary artery rings (average EC50 of 42 ± 19 nM). Incubation of coronary arteries with S18886 (1 nM) significantly attenuated coronary vasoconstriction to U46619 resulting in a rightward shift of the EC50 to 187 ± 38 nM (P < 0.02). Vehicle had no effect on U46619-induced contractions. Higher concentrations of S18886 dose-dependently reduced U46619-induced contractions. S18886 (1 nM) antagonized coronary vasoconstriction of prostaglandin F2α (10 µM) by 68% ± 5 (P < 0.0001) but had no effect on either acetylcholine or KCl-induced contraction. Data from this investigation indicate that S18886 is an effective antagonist of U46619-induced vasoconstriction in the porcine coronary circulation. While S18886 does not influence coronary smooth muscle response to either acetylcholine or activation of L-type Ca2+ channels, attenuation of prostaglandin F2α suggests antagonists specificity may extend beyond TxA2 receptor signaling.Item Impaired cardiovascular function in obese Ossabaw swine model of heart failure with preserved ejection fraction(2022) Weber, Theodore Van; Dick, Gregory; Gerlt, Deitrich; Bale, Alexander; Warne, CooperPresenter: Ted Weber Authors: Ted Weber, OMS-II; Deitrich Gerlt, Alex Bale, Cooper Warne, Gregory Dick PhD, Johnathan Tune, PhD Title: Impaired cardiovascular function in obese Ossabaw swine model of heart failure with preserved ejection fraction Background: The lack of pre-clinical large animal models of heart failure with preserved ejection fraction (HFpEF) remains a growing, yet unmet obstacle to improving understanding of this complex condition. Objective: The goal of this study was to examine cardiovascular responses to acute reductions in blood pressure in lean-control vs. obese Ossabaw swine with HFpEF (obese HF). Heart failure was induced by chronic tachycardia at 180 beats/min for ~4 weeks. We tested the hypothesis that rapid ventricular pacing would augment left ventricular end diastolic pressure, impair cardiac contractile function, and diminish regional myocardial perfusion. Methods: Following completion of pacing protocol, swine were anesthetized and instrumented for continuous measurements of hemodynamic parameters, left ventricular pressure, volume, and coronary blood flow. After measurements were obtained under baseline conditions, blood was serially removed to lower blood pressure in ~10 mmHg increments down to a mean arterial pressure of ~40 mmHg. Arterial and coronary venous blood samples were obtained at rest and during each reduction in blood pressure. Results: Chronic tachycardia significantly increased left ventricular end diastolic pressure (P < 0.001) but did not affect ejection fraction (P = 0.79) in obese HF (n = 5) vs. lean-control (n = 7) swine. Hemorrhage reduced blood pressure from 106 ± 5 mmHg to 40 ± 1 mmHg vs. 102 ± 4 mmHg to 41 ± 1 mmHg in lean-control and obese HF swine, respectively. Reductions in arterial pressure robustly increased heart rate from 73 ± 8 to 136 ± 19 beats/min in lean swine. In contrast, the reflexive heart rate response was significantly attenuated in obese HF, as evidenced by a 4-fold reduction in the slope of the relationship between heart rate and blood pressure in obese HF vs. lean-control swine (P < 0.01). These changes were associated with significant reductions in the relationship between cardiac index (cardiac output/body weight) and end diastolic volume (P < 0.01), while the ratio of subendocardial to subepicardial blood flow to the left ventricle remained consistent as blood pressure was diminished in lean-control and obese HF (P = 0.53). Conclusions: These findings support that chronic high-rate ventricular pacing of obese Ossabaw swine induces key phenotypic features of HFpEF, including elevated left ventricular end diastolic pressure with normal ejection fraction, chronotropic incompetence, and impaired ventricular contractility.Item The length-tension characteristics of small coronary arteries vary with transmural origin(2023) Essajee, Sal; Warne, Cooper; Tucker, Selina; Dick, Gregory; Tune, JohnathanThere are transmural differences in the structure of arteries across the left ventricular wall. For example, for arteries of the same size, wall thickness is greater in arteries of the epicardium than those from the endocardium. This observation suggests that there could be differences in their passive and active length-tension relationships, as different amounts of connective tissue or smooth muscle would be expected to alter these characteristics. We tested this hypothesis by studying similarly sized porcine coronary arteries from opposite transmural locations. Endocardial arteries had a diameter of 389 ± 33 µm (n = 8), while epicardial arteries measured 388 ± 50 µm (n = 6). A wire myograph was used to study the mechanical properties of these arteries under isometric conditions in KrebsHenseleit buffer at 37 oC. Arteries were cut into rings with an axial length of 2 mm. Rings were repetitively stimulated to contract at increasing lengths with the addition of high extracellular K + (80 mM). Coronary arteries developed active tension to a plateau level over approximately 3-5 min and K + -induced contractions readily washed out. Arteries from the epicardium were stiffer, as the passive-length tension curve of these vessels was elevated over arteries from the endocardium. Passive tensions at optimal length were 3.2 ± 0.4 vs. 5.6 ± 1.5 mN/mm (p < 0.05). The active tension developed in response to K + depolarization was greater in epicardial arteries. Active tensions at optimal length were 3.4 ± 1.1 vs. 2.4 ± 0.3 mN/mm (p < 0.05). Our results represent the first comparison of transmural differences in coronary arteries under isometric tension. Our findings support the hypothesis that differences exist in the passive and active length-tension relationships of epicardial and endocardial arteries that correlate with wall thickness.