Protection against ventricular arrhythmias and cardiac death using adenosine and lidocaine during regional ischemia in the in vivo rat

2004 ◽  
Vol 287 (3) ◽  
pp. H1286-H1295 ◽  
Author(s):  
Sarah J. Canyon ◽  
Geoffrey P. Dobson
Keyword(s):  
Infarct Size ◽  
Rat Model ◽  
Cardiac Death ◽  
Constant Infusion ◽  
Therapeutic Window ◽  
High Dose ◽  
Sprague Dawley ◽  
Myocardial Ischemia And Reperfusion ◽  
Regional Ischemia

Despite decades of research, there are few effective ways to treat ventricular fibrillation (VF), ventricular tachycardia (VT), or cardiac ischemia that show a significant survival benefit. Our aim was to investigate the combined therapeutic effect of two common antiarrhythmic compounds, adenosine and lidocaine (AL), on mortality, arrhythmia frequency and duration, and infarct size in the rat model of regional ischemia. Sprague-Dawley rats ( n = 49) were anesthetized with pentobarbital sodium (60 mg·ml−1·kg−1 ip) and instrumented for regional coronary occlusion (30 min) and reperfusion (120 min). Heart rate, blood pressure, and a lead II electrocardiogram were recorded. Intravenous pretreatment began 5 min before ischemia and extended throughout ischemia, terminating at the start of reperfusion. After 120 min, hearts were removed for infarct size measurement. Mortality occurred in 58% of saline controls ( n = 12), 50% of adenosine only (305 μg·kg−1·min−1, n = 8), 0% in lidocaine only (608 μg·kg−1·min−1, n = 8), and 0% in AL at any dose (152, 305, or 407 μg·kg−1·min−1 adenosine plus 608 μg·kg−1·min−1 lidocaine, n = 7, 8, and 6). VT occurred in 100% of saline controls (18 ± 9 episodes), 50% of adenosine-only (11 ± 7 episodes), 83% of lidocaine-only (23 ± 11 episodes), 60% of low-dose AL (2 ± 1 episodes, P < 0.05), 57% of mid-dose AL (2 ± 1 episodes, P < 0.05), and 67% of high-dose AL rats (6 ± 3 episodes). VF occurred in 75% of saline controls (4 ± 3 episodes), 100% of adenosine-only-treated rats (3 ± 2 episodes), and 33% lidocaine-only-treated rats (2 ± 1 episodes) of the rats tested. There was no deaths and no VF in the low- and mid-dose AL-treated rats during ischemia, and only one high-dose AL-treated rat experienced VF (25.5 sec). Infarct size was lower in all AL-treated rats but only reached significance with the mid-dose treatment (saline controls 61 ± 5% vs. 38 ± 6%, P < 0.05). We conclude that a constant infusion of a solution containing AL virtually abolished severe arrhythmias and prevented cardiac death in an in vivo rat model of acute myocardial ischemia and reperfusion. AL combinational therapy may provide a primary prevention therapeutic window in ischemic and nonischemic regions of the heart.

scholarly journals Effects of Pentoxifylline in a Rat Model of Manganism: Evaluation of the Possible Toxicity

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Romina Tanideh ◽  
Omid Farshad ◽  
Akram Jamshidzadeh ◽  
Aida Iraji
Keyword(s):  
Rat Model ◽  
Muscle Relaxation ◽  
Tissue Perfusion ◽  
Smooth Muscle Relaxation ◽  
Control Group ◽  
High Dose ◽  
Sprague Dawley ◽  
Total Antioxidant ◽  
The Brain

Objective. Manganese (Mn) has been reported, through dietary and occupational overexposure, to induce neurotoxicity named manganism. Pentoxifylline (PTX) administration attracts much attention considering the beneficial properties of PTX, as an anti-inflammatory and smooth muscle relaxation agent. This in vivo study aims to evaluate the effect of PTX on manganism in rat model. Materials and Methods. Thirty adult male Sprague Dawley rats received MnCl2 (100 mg/kg, i.p. on days 1, 3, and 7) during a week alone or in combination with PTX (300 mg/kg, i.p. every day for 8 consecutive days on manganism rat model). Several locomotor activity indices, as well as biomarkers of oxidative stress, were monitored in the brain tissue of Mn-exposed animals. Results. It was found that PTX supplementation (300 mg/kg, i.p.) deteriorated the Mn-induced locomotor deficit. This drug also increased the Mn brain accumulation as well as reactive oxygen species (ROS) and lipid peroxidation products in the manganism rat model. Moreover, the levels of total antioxidant capacity (TAC) and glutathione (GSH) were shown to be reduced significantly compared to the control group. Conclusion. The results of this study revealed that PTX at a high dose (300 mg/kg) might increase manganism complications. PTX lowers the blood viscosity, improves the tissue perfusion, and increases the Mn levels in the brain.

scholarly journals Intra-articular Injection of Cell-laden 3D Microcryogels Empower Low-dose Cell Therapy for Osteoarthritis in a Rat Model

2020 ◽  
Vol 29 ◽  
pp. 096368972093214
Author(s):  
Dan Xing ◽  
Wei Liu ◽  
Bin Wang ◽  
Jiao Jiao Li ◽  
Yu Zhao ◽  
...  
Keyword(s):  
Cell Therapy ◽  
Rat Model ◽  
Low Dose ◽  
High Rate ◽  
Saline Control ◽  
High Dose ◽  
Sprague Dawley ◽  
Osteoarthritic Joint

Intra-articular injection of mesenchymal stem cells (MSCs) in an osteoarthritic joint can help slow down cartilage destruction. However, cell survival and the efficiency of repair are generally low due to mechanical damage during injection and a high rate of cell loss. We, thus, investigated an improved strategy for cell delivery to an osteoarthritic joint through the use of three-dimensional (3D) microcryogels. MSCs were seeded into 3D microcryogels. The viability and proliferation of MSCs in microcryogels were determined over 5 d, and the phenotype of MSCs was confirmed through trilineage differentiation tests and flow cytometry. In Sprague Dawley rats with induced osteoarthritis (OA) of the knee joint, a single injection was made with the following groups: saline control, low-dose free MSCs (1 × 105 cells), high-dose free MSCs (1 × 106 cells), and microcryogels + MSCs (1 × 105 cells). Cartilage degeneration was evaluated by macroscopic examination, micro-computed tomographic analysis, and histology. MSCs grown in microcryogels exhibited optimal viability and proliferation at 3 d with stable maintenance of phenotype in vitro. Microcryogels seeded with MSCs were, therefore, primed for 3 d before being used for in vivo experiments. At 4 and 8 wk, the microcryogels + MSCs and high-dose free MSC groups had significantly higher International Cartilage Repair Society macroscopic scores, histological evidence of more proteoglycan deposition and less cartilage loss accompanied by a lower Mankin score, and minimal radiographic evidence of osteoarthritic changes in the joint compared to the other two groups. In conclusion, intra-articular injection of cell-laden 3D microcryogels containing a low dose of MSCs can achieve similar effects as a high dose of free MSCs for OA in a rat model. Primed MSCs in 3D microcryogels can be considered as an improved delivery strategy for cell therapy in treating OA that minimizes cell dose while retaining therapeutic efficacy.

scholarly journals In Vivo Measurement of Neurochemical Abnormalities in the Hippocampus in a Rat Model of Cuprizone-Induced Demyelination

Diagnostics ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 45
Author(s):  
Do-Wan Lee ◽  
Jae-Im Kwon ◽  
Chul-Woong Woo ◽  
Hwon Heo ◽  
Kyung Won Kim ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Rat Model ◽  
Resonance Spectroscopy ◽  
Chow Diet ◽  
Gamma Aminobutyric Acid ◽  
Sprague Dawley ◽  
In Vivo Measurement ◽  
Hippocampal Lesions ◽  
Total Creatine

This study quantitatively measured the changes in metabolites in the hippocampal lesions of a rat model of cuprizone-induced demyelination as detected using in vivo 7 T proton magnetic resonance spectroscopy. Nineteen Sprague Dawley rats were randomly divided into two groups and fed a normal chow diet or cuprizone (0.2%, w/w) for 7 weeks. Demyelinated hippocampal lesions were quantitatively measured using a 7 T magnetic resonance imaging scanner. All proton spectra were quantified for metabolite concentrations and relative ratios. Compared to those in the controls, the cuprizone-induced rats had significantly higher concentrations of glutamate (p = 0.001), gamma-aminobutyric acid (p = 0.019), and glutamate + glutamine (p = 0.001); however, creatine + phosphocreatine (p = 0.006) and myo-inositol (p = 0.001) concentrations were lower. In addition, we found that the glutamine and glutamate complex/total creatine (p < 0.001), glutamate/total creatine (p < 0.001), and GABA/total creatine (p = 0.002) ratios were significantly higher in cuprizone-treated rats than in control rats. Our results showed that cuprizone-induced neuronal demyelination may influence the severe abnormal metabolism in hippocampal lesions, and these responses could be caused by microglial activation, mitochondrial dysfunction, and astrocytic necrosis.

scholarly journals Translational Research in FLASH Radiotherapy—From Radiobiological Mechanisms to In Vivo Results

Biomedicines ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 181
Author(s):  
Loredana G. Marcu ◽  
Eva Bezak ◽  
Dylan D. Peukert ◽  
Puthenparampil Wilson
Keyword(s):  
Dose Rate ◽  
High Dose Rate ◽  
Current Status ◽  
Therapeutic Window ◽  
High Dose ◽  
Linear Accelerators ◽  
Radiation Delivery ◽  
Tissue Sparing

FLASH radiotherapy, or the administration of ultra-high dose rate radiotherapy, is a new radiation delivery method that aims to widen the therapeutic window in radiotherapy. Thus far, most in vitro and in vivo results show a real potential of FLASH to offer superior normal tissue sparing compared to conventionally delivered radiation. While there are several postulations behind the differential behaviour among normal and cancer cells under FLASH, the full spectra of radiobiological mechanisms are yet to be clarified. Currently the number of devices delivering FLASH dose rate is few and is mainly limited to experimental and modified linear accelerators. Nevertheless, FLASH research is increasing with new developments in all the main areas: radiobiology, technology and clinical research. This paper presents the current status of FLASH radiotherapy with the aforementioned aspects in mind, but also to highlight the existing challenges and future prospects to overcome them.

scholarly journals Comparison of different techniques for estimating rates of protein synthesis in vivo in healthy and bacteraemic rats

1985 ◽  
Vol 226 (1) ◽  
pp. 37-42 ◽  
Author(s):  
J J Pomposelli ◽  
J D Palombo ◽  
K J Hamawy ◽  
B R Bistrian ◽  
G L Blackburn ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Rectus Muscle ◽  
Stochastic Modelling ◽  
Whole Body ◽  
Constant Infusion ◽  
Second Phase ◽  
Sprague Dawley ◽  
Body Protein ◽  
To Receive

Previous studies have reported that use of a flooding dose of radiolabelled amino acid is a more precise technique than the constant infusion of tracer quantities for determining rates of protein synthesis in rapidly turning-over tissues in the rat. However, there has been little direct investigation comparing different methods under comparable conditions. Initially, 12 healthy male Sprague-Dawley rats, weighing approx. 100 g, were randomized to receive either a bolus intravenous injection of 100 mumol of L-leucine (containing 30 microCi of [1-14C]leucine)/100 g body wt., or a continuous 2 h tracer infusion of [14C]leucine. In the second phase of the experiment, 12 additional rats were intravenously injected with 1 × 10(8) colony-forming units of Pseudomonas aeruginosa and 16 h later randomized to receive one of two infusions described above. Total protein synthesis as well as fractional synthesis rates were determined in liver, rectus muscle and whole body. Synthesis rates measured in liver, muscle and whole body were significantly higher in bacteraemic rats than in healthy rats. The flooding-dose methodology gave significantly higher estimates of protein synthesis in the liver, skeletal muscle and whole body than did the continuous-infusion method using direct measurement of the acid-soluble fraction from the respective tissue. Indirect estimates of whole-body protein synthesis based on plasma enrichments and stochastic modelling gave the lowest values.

scholarly journals Effect of GuiXiong Xiaoyi Wan in Treatment of Endometriosis on Rats

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Zhixing Jin ◽  
Li Wang ◽  
Zhiling Zhu
Keyword(s):  
Cell Proliferation ◽  
Rat Model ◽  
Flow Cytometric Analysis ◽  
Lesion Size ◽  
Negative Control ◽  
Terminal Deoxynucleotidyl Transferase ◽  
High Dose ◽  
Sprague Dawley ◽  
Induced Apoptosis ◽  
Cd4 Lymphocytes

Objective. To evaluate the effect of GuiXiong Xiaoyi Wan (GXXYW) on the development of endometriosis in a rat model.Methods. Sprague-Dawley rats with surgically induced endometriosis were randomly treated with low-dose GXXYW, high-dose GXXYW, or vehicle (negative control) for 28 days. Immunohistochemistry was used to assess cell proliferation in the lesions. The terminal deoxynucleotidyl transferase- (TdT-) mediated dUTP biotin nick end labelling (TUNEL) method was performed to analyse the apoptosis induced by GuiXiong Xiaoyi Wan. The percentages of CD3+ lymphocytes, CD4+ lymphocytes, and CD8+ lymphocytes in the spleens of the rats were evaluated using flow cytometric analysis.Results. Treatment with GXXYW significantly decreased the lesion size, inhibited cell proliferation, and induced apoptosis in endometriotic tissue. The spleens of GXXYW-treated rats also demonstrated a significant increase in the percentage of CD4+ lymphocytes and a significant decrease in the percentage of CD8+ lymphocytes.Conclusions. These results suggest that, in a rat model, GXXYW may be effective in the suppression of the growth of endometriosis, possibly through the inhibition of cell proliferation, the induction of apoptosis of endometriotic cells, and the regulation of the immune system.

Endogenous myocardial norepinephrine is not essential for ischemic preconditioning in rabbit heart

1996 ◽  
Vol 270 (3) ◽  
pp. H1078-H1084 ◽  
Author(s):  
J. L. Ardell ◽  
X. M. Yang ◽  
B. A. Barron ◽  
J. M. Downey ◽  
M. V. Cohen
Keyword(s):  
Infarct Size ◽  
Ischemic Preconditioning ◽  
Rabbit Heart ◽  
Chemical Sympathectomy ◽  
Single Cycle ◽  
Risk Zone ◽  
Regional Ischemia ◽  
Norepinephrine Content ◽  
Ischemic Period

To determine whether endogenous cardiac catecholamines mediate ischemic preconditioning (PC) in the rabbit heart, myocardial catecholamines were depleted by reserpine (5 mg/kg, 18-24 h pre-PC) or surgical sympathectomy (2 wk pre-PC). In vivo hearts were subjected to 30 min of regional ischemia and 3 h of reperfusion. PC involved either one or four cycles of 5-min ischemia and 10-min reperfusion before the 30-min ischemic period. Right ventricular norepinephrine content (pmol/mg protein), 51.4 +/- 11.1 in untreated rabbits, was reduced to 0.6 +/- 0.2 and 1.8 +/- 0.5 by surgical sympathectomy and reserpine, respectively. Infarct size (IS) was measured by tetrazolium and expressed as percentage of the risk zone. In untreated animals exposed solely to 30 min of regional ischemia IS was 35.5 +/- 1.6% and was unchanged by reserpine (43.3 +/- 5.4%) or surgical sympathectomy (33.4 +/- 3.5%). compared with infarction in the respective non-PC controls, IS in untreated (7.4 +/- 1.5%, P < 0.0001) and surgically sympathectomized (11.2 +/- 1.5%, P < 0.0001) animals was significantly diminished by a single cycle of PC, but the latter exerted less protection in reserpinized animals (27.6 +/- 3.5%, P < 0.0025). Four cycles of PC, however, reduced IS to 10.3 +/- 1.2% in reserpinized animals. Therefore, despite comparable depression of myocardial norepinephrine content, surgical and chemical sympathectomy had different effects on the level of protection afforded by ischemic PC. These data demonstrate that endogenous myocardial catecholamines are not essential for protection from PC in the rabbit.

scholarly journals The FLASH effect depends on oxygen concentration

2020 ◽  
Vol 93 (1106) ◽  
pp. 20190702 ◽  
Author(s):  
Gabriel Adrian ◽  
Elise Konradsson ◽  
Michael Lempart ◽  
Sven Bäck ◽  
Crister Ceberg ◽  
...  
Keyword(s):  
Oxygen Concentration ◽  
Underlying Mechanism ◽  
Oxygen Depletion ◽  
Therapeutic Window ◽  
High Dose ◽  
Dose Rates ◽  
Conventional Dose ◽  
Oxygen Concentrations

Objective: Recent in vivo results have shown prominent tissue sparing effect of radiotherapy with ultra-high dose rates (FLASH) compared to conventional dose rates (CONV). Oxygen depletion has been proposed as the underlying mechanism, but in vitro data to support this have been lacking. The aim of the current study was to compare FLASH to CONV irradiation under different oxygen concentrations in vitro. Methods: Prostate cancer cells were irradiated at different oxygen concentrations (relative partial pressure ranging between 1.6 and 20%) with a 10 MeV electron beam at a dose rate of either 600 Gy/s (FLASH) or 14 Gy/min (CONV), using a modified clinical linear accelerator. We evaluated the surviving fraction of cells using clonogenic assays after irradiation with doses ranging from 0 to 25 Gy. Results: Under normoxic conditions, no differences between FLASH and CONV irradiation were found. For hypoxic cells (1.6%), the radiation response was similar up to a dose of about 5–10 Gy, above which increased survival was shown for FLASH compared to CONV irradiation. The increased survival was shown to be significant at 18 Gy, and the effect was shown to depend on oxygen concentration. Conclusion: The in vitro FLASH effect depends on oxygen concentration. Further studies to characterize and optimize the use of FLASH in order to widen the therapeutic window are indicated. Advances in knowledge: This paper shows in vitro evidence for the role of oxygen concentration underlying the difference between FLASH and CONV irradiation.

The effect of an adenosine and lidocaine intravenous infusion on myocardial high-energy phosphates and pH during regional ischemia in the rat model in vivo

2006 ◽  
Vol 84 (8-9) ◽  
pp. 903-912 ◽  
Author(s):  
Sarah J. Canyon ◽  
Geoffrey P. Dobson
Keyword(s):  
Body Mass ◽  
Rat Model ◽  
Intravenous Infusion ◽  
High Energy ◽  
Coronary Artery Ligation ◽  
Ischemia And Reperfusion ◽  
High Energy Phosphates ◽  
Regional Ischemia ◽  
Significant Difference

We have previously shown that an intravenous infusion of adenosine and lidocaine (AL) solution protects against death and severe arrhythmias and reduces infarct size in the in vivo rat model of regional ischemia. The aim of this study was to examine the relative changes of myocardial high-energy phosphates (ATP and PCr) and pH in the left ventricle during ischemia–reperfusion using 31P NMR in AL-treated rats (n = 7) and controls (n = 6). The AL solution (A: 305 μg·(kg body mass)–1·min–1; L: 608 μg·(kg body mass)–1·min–1) was administered intravenously 5 min before and during 30 min coronary artery ligation. Two controls died from ventricular fibrillation; no deaths were recorded in AL-treated rats. In controls that survived, ATP fell to 73% ± 29% of baseline by 30 min ischemia and decreased further to 68% ± 28% during reperfusion followed by a sharp recovery at the end of the reperfusion period. AL-treated rats maintained relatively constant ATP throughout ischemia and reperfusion ranging from 95% ± 6% to 121% ± 10% of baseline. Owing to increased variability in controls, these results were not found to be significant. In contrast, control [PCr] was significantly reduced in controls compared with AL-treated rats during ischemia at 10 min (68% ± 7% vs. 99% ± 6%), at 15 min (68% ± 10% vs. 93% ± 2%), and at 20 min (67% ± 15% vs. 103% ± 5%) and during reperfusion at 10 min (56% ± 22% vs. 99% ± 7%), at 15 min (60% ± 10% vs. 98% ± 7%), and at 35 min (63% ± 14% vs. 120% ± 11%) (p < 0.05). Interestingly, changes in intramyocardial pH between each group were not significantly different during ischemia and fell by about 1 pH unit to 6.6. During reperfusion, pH in AL-treated rats recovered to baseline in 5 min but not in controls, which recovered to only around pH 7.1. There was no significant difference in the heart rate, mean arterial pressure, and rate-pressure product between the controls and AL treatment during ischemia and reperfusion. We conclude that AL cardioprotection appears to be associated with the preservation of myocardial high-energy phosphates, downregulation of the heart at the expense of a high acid-load during ischemia, and with a rapid recovery of myocardial pH during reperfusion.

scholarly journals Pharmacodynamic Activity and Efficacy of Linezolid in a Rat Model of Pneumococcal Pneumonia

2002 ◽  
Vol 46 (5) ◽  
pp. 1345-1351 ◽  
Author(s):  
Martha J. Gentry-Nielsen ◽  
Keith M. Olsen ◽  
Laurel C. Preheim
Keyword(s):  
Rat Model ◽  
Pneumococcal Pneumonia ◽  
Free Fraction ◽  
Lavage Fluid ◽  
Treated Group ◽  
High Dose ◽  
Time Curve ◽  
A Value

ABSTRACT Linezolid is a new oxazolidinone antibiotic with potent activity against gram-positive bacteria, including Streptococcus pneumoniae. The pharmacodynamic activity and in vivo efficacy of linezolid were compared to those of ceftriaxone in an immunocompetent rat model of pneumococcal pneumonia. Rats infected intratracheally with 8 × 107 CFU of a penicillin-sensitive (MIC, 0.032 μg/ml) strain of S. pneumoniae were treated for 5 days beginning 18 h postinfection. Groups of rats were sham treated with oral phosphate-buffered saline or received oral liquid linezolid at 25 or 50 mg/kg of body weight twice a day (b.i.d.) or subcutaneous ceftriaxone at 100 mg/kg once daily. Mortality was monitored for 10 days postinfection; blood culturing was performed on day 1 (pretreatment) and on days 3, 5, and 10 postinfection for the determination of bacteremia. Serum also was collected for the determination of pharmacokinetic and pharmacodynamic parameters at 30 min and at 3, 5, and 12 h (linezolid) or 3, 5, and 24 h (ceftriaxone) postdose. The cumulative mortality rates were 100% for the sham-treated group, 58.3% for the low-dose linezolid group, 8.3% for the high-dose linezolid group, and 0% for the ceftriaxone group. Rats in each of the antibiotic treatment groups had significantly fewer bacteria (P < 0.00001) in their bronchoalveolar lavage fluid (BALF) on day 3 postinfection than sham-treated rats. There also were significantly fewer organisms in the BALF of rats treated with ceftriaxone than in the BALF of rats treated with either dose of linezolid. Oral linezolid at 50 mg/kg b.i.d. therefore was as effective as ceftriaxone in experimental pneumococcal pneumonia, whereas the 25-mg/kg b.i.d. dose was significantly less effective. All pharmacodynamic parameters reflected efficacy and were significantly different for the two dosage regimens of linezolid (P < 0.01). However, the free-fraction pharmacodynamic parameters predictive of outcome were a value of >39% for the percentage of time in the experimental dosing interval during which the linezolid concentration exceeded the MIC and a value of >147 for the ratio of the area under the serum concentration-time curve to the MIC.

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