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1.
Nephrol Dial Transplant ; 33(12): 2128-2138, 2018 12 01.
Article in English | MEDLINE | ID: mdl-29660027

ABSTRACT

Background: Mitochondrial dysfunction plays an important role in kidney damage in various pathologies, including acute and chronic kidney injury and diabetic nephropathy. In addition to the well-studied ischaemia/reperfusion (I/R) injury, hypothermia/rewarming (H/R) also inflicts acute kidney injury. Substituted 6-hydroxychromanols are a novel class of mitochondrial medicines that ameliorate mitochondrial oxidative stress and protect the mitochondrial network. To identify a novel 6-hydroxychromanol that protects mitochondrial structure and function in the kidney during H/R, we screened multiple compounds in vitro and subsequently assessed the efficacy of the 6-hydroxychromanol derivatives SUL-109 and SUL-121 in vivo to protect against kidney injury after H/R in rats. Methods: Human proximal tubule cell viability was assessed following exposure to H/R for 48/4 h in the presence of various 6-hydroxychromanols. Selected compounds (SUL-109, SUL-121) or vehicle were administered to ketamine-anaesthetized male Wistar rats (IV 135 µg/kg/h) undergoing H/R at 15°C for 3 h followed by rewarming and normothermia for 1 h. Metabolic parameters and body temperature were measured throughout. In addition, renal function, renal injury, histopathology and mitochondrial fitness were assessed. Results: H/R injury in vitro lowered cell viability by 94 ± 1%, which was counteracted dose-dependently by multiple 6-hydroxychomanols derivatives. In vivo, H/R in rats showed kidney injury molecule 1 expression in the kidney and tubular dilation, accompanied by double-strand DNA breaks and protein nitrosylation. SUL-109 and SUL-121 ameliorated tubular kidney damage, preserved mitochondrial mass and maintained cortical adenosine 5'-triphosphate (ATP) levels, although SUL-121 did not reduce protein nitrosylation. Conclusions: The substituted 6-hydroxychromanols SUL-109 and SUL-121 ameliorate kidney injury during in vivo H/R by preserving mitochondrial mass, function and ATP levels. In addition, both 6-hydroxychromanols limit DNA damage, but only SUL-109 also prevented protein nitrosylation in tubular cells. Therefore SUL-109 offers a promising therapeutic strategy to preserve kidney mitochondrial function.


Subject(s)
Acute Kidney Injury/prevention & control , Chromans/chemistry , Cryoprotective Agents/pharmacology , Hypothermia/complications , Reperfusion Injury/prevention & control , Rewarming/adverse effects , Acute Kidney Injury/etiology , Acute Kidney Injury/pathology , Animals , Chromans/pharmacology , Chromans/therapeutic use , Cryoprotective Agents/chemistry , Humans , Male , Mitochondria/metabolism , Organ Preservation Solutions , Oxidative Stress , Rats , Rats, Wistar
2.
Mol Imaging Biol ; 18(5): 715-23, 2016 10.
Article in English | MEDLINE | ID: mdl-27091332

ABSTRACT

PURPOSE: Small animal positron emission tomography (PET) can be used to detect small changes in neuroreceptor availability. This often requires rapid arterial blood sampling. However, current catheterization procedures do not allow repeated blood sampling. We have developed a procedure which allows arterial sampling on repeated occasions in the same animal. PROCEDURES: Eleven male Wistar rats were two times catheterized via a superficial branch of a femoral artery and scanned with [(11)C]MPDX and blood sampling. PET images were co-registered to a magnetic resonance imaging (MRI) template. Regional tracer distribution volumes (V T) in the brain were calculated by the Logan analysis. The procedure was repeated after 1 week. RESULTS: Surgery was successful in 90 % of the cases, and discomfort was minor. The V T data showed small differences between test and retest, low between subject variability, and a strong agreement between and within subjects. CONCLUSION: Repeated quantitative imaging with a high reproducibility is possible with this approach.


Subject(s)
Blood Specimen Collection/methods , Positron-Emission Tomography/methods , Xanthines/chemistry , Animals , Body Weight , Ligands , Male , Rats, Wistar , Receptor, Adenosine A1/metabolism , Reproducibility of Results
3.
Eur J Pharmacol ; 769: 225-33, 2015 Dec 15.
Article in English | MEDLINE | ID: mdl-26593431

ABSTRACT

Hypothermia and rewarming produces organ injury through the production of reactive oxygen species. We previously found that dopamine prevents hypothermia and rewarming-induced apoptosis in cultured cells through increased expression of the H2S-producing enzyme cystathionine ß-Synthase (CBS). Here, we investigate whether dopamine protects the kidney in deep body cooling and explore the role of H2S-producing enzymes in an in vivo rat model of deep hypothermia and rewarming. In anesthetized Wistar rats, body temperature was decreased to 15°C for 3h, followed by rewarming for 1h. Rats (n≥5 per group) were treated throughout the procedure with vehicle or dopamine infusion, and in the presence or absence of a non-specific inhibitor of H2S-producing enzymes, amino-oxyacetic acid (AOAA). Kidney damage and renal expression of three H2S-producing enzymes (CBS, CSE and 3-MST) was quantified and serum H2S level measured. Hypothermia and rewarming induced renal damage, evidenced by increased serum creatinine, renal reactive oxygen species production, KIM-1 expression and influx of immune cells, which was accompanied by substantially lowered renal expression of CBS, CSE, and 3-MST and lowered serum H2S levels. Infusion of dopamine fully attenuated renal damage and maintained expression of H2S-producing enzymes, while normalizing serum H2S. AOAA further decreased the expression of H2S-producing enzymes and serum H2S level, and aggravated renal damage. Hence, dopamine preserves renal integrity during deep hypothermia and rewarming likely by maintaining the expression of renal H2S-producing enzymes and serum H2S.


Subject(s)
Dopamine/pharmacology , Hydrogen Sulfide/metabolism , Hypothermia/enzymology , Kidney/enzymology , Kidney/injuries , Rewarming/adverse effects , Aminooxyacetic Acid/pharmacology , Anesthesia, General , Animals , Enzyme Inhibitors/pharmacology , Gene Expression Regulation, Enzymologic/drug effects , Hemodynamics/drug effects , Hydrogen Sulfide/blood , Hypothermia/metabolism , Hypothermia/pathology , Hypothermia/physiopathology , Kidney/drug effects , Kidney/physiopathology , Male , Rats , Rats, Wistar
4.
PLoS One ; 9(5): e97196, 2014.
Article in English | MEDLINE | ID: mdl-24819611

ABSTRACT

BACKGROUND: Cardiopulmonary bypass (CPB) may induce systemic inflammation and vascular dysfunction. Sphingosine 1-phosphate (S1P) modulates various vascular and immune responses. Here we explored whether agonists of the S1P receptors, FTY720 and SEW2871 improve vascular reactivity after CPB in the rat. METHODS: Experiments were done in male Wistar rats (total n = 127). Anesthesia was induced by isoflurane (2.5-3%) and maintained by fentanyl and midazolam during CPB. After catheterization of the left femoral artery, carotid artery and the right atrium, normothermic extracorporeal circulation was instituted for 60 minutes. In the first part of the study animals were euthanized after either 1 hour, 1 day, 2 or 5 days of the recovery period. In second part of the study animals were euthanized after 1 day of postoperative period. We evaluated the contractile response to phenylephrine (mesenteric arteries) or to serotonin (coronary artery) and vasodilatory response to acethylcholine (both arteries). RESULTS: Contractile responses to phenylephrine were reduced at 1 day recovery after CPB and Sham as compared to healthy control animals (Emax, mN: 7.9 ± 1.9, 6.5 ± 1.5, and 11.3 ± 1.3, respectively). Mainly FTY720, but not SEW2871, caused lymphopenia in both Sham and CPB groups. In coronary and mesenteric arteries, both FTY720 and SEW2871 normalized serotonin and phenylephrine-mediated vascular reactivity after CPB (p<0.05) and FTY720 increased relaxation to acetylcholine as compared with untreated rats that underwent CPB. CONCLUSION: Pretreatment with FTY720 or SEW2871 preserves vascular function in mesenteric and coronary artery after CPB. Therefore, pharmacological activation of S1P1 receptors may provide a promising therapeutic intervention to prevent CPB-related vascular dysfunction in patients.


Subject(s)
Cardiopulmonary Bypass/adverse effects , Coronary Vessels/physiology , Lymphocytes/cytology , Mesenteric Arteries/physiology , Receptors, Lysosphingolipid/metabolism , Animals , Blood Gas Analysis , Cell Count , Coronary Vessels/drug effects , Fingolimod Hydrochloride , Follow-Up Studies , Interleukin-6/blood , Lymphocytes/drug effects , Male , Mesenteric Arteries/drug effects , Oxadiazoles/pharmacology , Propylene Glycols/pharmacology , Rats , Rats, Wistar , Receptors, Lysosphingolipid/agonists , Sphingosine/analogs & derivatives , Sphingosine/pharmacology , Thiophenes/pharmacology , Vasoconstriction/drug effects , Vasodilation/drug effects
5.
PLoS One ; 9(4): e93218, 2014.
Article in English | MEDLINE | ID: mdl-24722364

ABSTRACT

Hibernation is an energy-conserving behavior in winter characterized by two phases: torpor and arousal. During torpor, markedly reduced metabolic activity results in inactivity and decreased body temperature. Arousal periods intersperse the torpor bouts and feature increased metabolism and euthermic body temperature. Alterations in physiological parameters, such as suppression of hemostasis, are thought to allow hibernators to survive periods of torpor and arousal without organ injury. While the state of torpor is potentially procoagulant, due to low blood flow, increased viscosity, immobility, hypoxia, and low body temperature, organ injury due to thromboembolism is absent. To investigate platelet dynamics during hibernation, we measured platelet count and function during and after natural torpor, pharmacologically induced torpor and forced hypothermia. Splenectomies were performed to unravel potential storage sites of platelets during torpor. Here we show that decreasing body temperature drives thrombocytopenia during torpor in hamster with maintained functionality of circulating platelets. Interestingly, hamster platelets during torpor do not express P-selectin, but expression is induced by treatment with ADP. Platelet count rapidly restores during arousal and rewarming. Platelet dynamics in hibernation are not affected by splenectomy before or during torpor. Reversible thrombocytopenia was also induced by forced hypothermia in both hibernating (hamster) and non-hibernating (rat and mouse) species without changing platelet function. Pharmacological torpor induced by injection of 5'-AMP in mice did not induce thrombocytopenia, possibly because 5'-AMP inhibits platelet function. The rapidness of changes in the numbers of circulating platelets, as well as marginal changes in immature platelet fractions upon arousal, strongly suggest that storage-and-release underlies the reversible thrombocytopenia during natural torpor. Possibly, margination of platelets, dependent on intrinsic platelet functionality, governs clearance of circulating platelets during torpor.


Subject(s)
Blood Platelets/cytology , Hypothermia, Induced , Torpor , Adenosine Diphosphate/chemistry , Animals , Arousal/physiology , Body Temperature , Cricetinae , Female , Hibernation , Male , Mesocricetus , Mice , Mice, Inbred C57BL , P-Selectin/metabolism , Rats , Rats, Wistar , Seasons , Thrombocytopenia/physiopathology , Time Factors
6.
Eur J Anaesthesiol ; 30(8): 492-500, 2013 Aug.
Article in English | MEDLINE | ID: mdl-23344121

ABSTRACT

CONTEXT: Cardiopulmonary bypass (CPB) is a commonly used technique in cardiac surgery but is associated with acute, transient, renal dysfunction that has a negative impact on long-term survival. OBJECTIVE: To unravel the molecular pathogenesis of renal injury following CPB. DESIGN: To obtain insight into the pathogenesis of renal dysfunction following CPB, we performed a microarray analysis of renal gene expression in the rat. SETTING: University Medical Centre Groningen. INTERVENTION: Rats underwent CPB or a sham procedure for 60 min and were sacrificed at 60 min, 1 and 5 days after the procedure. MAIN OUTCOME MEASURES: Renal gene expression profile as determined by microarray analysis. RESULTS: Expression of 420 genes was significantly altered in CPB compared to the sham procedure, and in 407 genes, this was evident in the acute phase (60 min) following CPB. Gene ontology analysis revealed 28 of these genes were involved in inflammatory responses, with high expression of genes downstream of mitogen-activated protein-kinase (MAP-kinase) signalling pathways. Potent inducers identified are from the interleukin-6 cytokine family that consists of interleukin-6 and oncostatin M (OSM), which signal through the gp130-cytokine receptor complex. The plasma concentration of interleukin-6 was hugely increased by CPB as measured by ELISA. Expression of genes downstream of these signalling pathways that lead to production of chemokines, adhesion molecules and molecules involved in coagulative pathways, was upregulated. CONCLUSION: CPB induces an acute and local inflammatory response in the kidney, which might contribute to renal injury. The signalling pathways involved identified by gene expression analysis may represent pharmacological targets to limit renal injury following CPB.


Subject(s)
Cardiopulmonary Bypass/adverse effects , Inflammation/pathology , Kidney/metabolism , Transcriptome , Animals , Gene Expression Profiling , Gene Expression Regulation , Kidney/injuries , Kidney/physiopathology , MAP Kinase Signaling System , Oligonucleotide Array Sequence Analysis , Rats , Rats, Wistar , Signal Transduction , Time Factors
7.
J Pharmacol Toxicol Methods ; 67(2): 82-90, 2013.
Article in English | MEDLINE | ID: mdl-23328058

ABSTRACT

INTRODUCTION: Rat models of cardiopulmonary bypass (CPB) have been used to examine the mechanisms of associated organ damage and to test intervention strategies. However, these models only partly mimic the clinical situation, because of the use of blood transfusion and arterial inflow via the tail artery. Thus a model using arterial inflow in the aorta and a miniaturized CPB circuit without need of transfusion was validated by examining intra-procedure characteristics, mortality and the effects of CPB on biomarkers of inflammation and cerebral injury during 5days follow-up. METHODS: Male Wistar rats (n=95) were anesthetized with isoflurane (2.5%) and fentanyl/midazolam during CPB. Animals were assigned to Control (n=6), Sham (n=40) or normothermic CPB (n=49) groups. Both Sham and CPB were cannulated in the aorta via the left carotid artery and in the right common jugular vein for access into the right heart. Extracorporeal circulation (ECC) was instituted for 60min only in CPB at a flow rate of 120mLkg(-1)min(-1) employing a CPB circuit of 15ml primed with 6% hydroxyethyl starch 60mgml(-1) solution. Rats were sacrificed at either 1h or 1, 2 or 5days after Sham or weaning from CPB. Plasma IL-6 and s100Beta levels were measured and blood cell counts were performed. RESULTS: Mortality in CPB animals (3 out of 49) and Sham (4 out of 40) did not differ (chi-square=0.46, dF=1, P>0.5). Compared to baseline (1.87±0.46∗10^9cells/L), Sham procedure (cannulation and anesthesia) significantly increased blood neutrophil count at the end of the period matching ECC (6.34±2.36∗10^9cells/L, P<0.05). CPB induced neutrophilia which persisted during 24h recovery. Also, CPB caused a rapid and prominent increase in plasma IL-6 from the first hour of the postoperative period (~1200pg/ml) with continuation (50-90pg/ml) up to 5th day of recovery. S100Beta levels were above detection level only in 3 out of 42 samples from CPB animals. DISCUSSION: Our rat model of CPB without homologous blood transfusion produces a reproducible and reliable systemic inflammatory response, with low mortality rates on long term follow up. The model more closely mimics the human situation in respect to arterial inflow site and avoidance of blood transfusion. Thus, our CPB model is suitable to study its influence on systemic inflammation, ischemia-reperfusion injury, microcirculation and vascular dysfunction in vivo, and to evaluate potential therapeutic interventions.


Subject(s)
Brain Diseases/prevention & control , Cardiopulmonary Bypass/adverse effects , Inflammation/etiology , Medical Errors/prevention & control , Postoperative Complications/prevention & control , Problem Solving , Animals , Artifacts , Biomarkers/blood , Blood Transfusion , Brain Diseases/blood , Brain Diseases/etiology , Cardiopulmonary Bypass/methods , Cardiopulmonary Bypass/mortality , Equipment Design , Inflammation/blood , Interleukin-6/blood , Male , Models, Animal , Postoperative Complications/etiology , Rats , Rats, Wistar , Survival Rate
8.
Anesthesiology ; 117(1): 126-36, 2012 Jul.
Article in English | MEDLINE | ID: mdl-22634873

ABSTRACT

BACKGROUND: The incidence of acute kidney injury following severe sepsis is higher in the elderly. We hypothesized that microvascular endothelium is "primed" by aging and that sepsis represents a "second hit," resulting in more severe microvascular complications. METHODS: Three- and 18-months-old mice were intraperitoneally injected with 1,500 EU/g body weight lipopolysaccharide and sacrificed after 8 h. Flow cytometry and myeloperoxidase ELISA determined neutrophils in plasma. Quantitative reverse transcription polymerase chain reaction was used to analyze messenger ribonucleic acid levels of cell adhesion molecules P-selectin and E-selectin, vascular cell adhesion protein-1, intercellular adhesion molecule-1, angiopoietin receptor TIE-2, and angiopoietins Ang1 and Ang2. In kidney tissue we assessed neutrophil influx and E-selectin protein expression. Neutrophils were depleted with the monoclonal antibody NIMP. RESULTS: At basal conditions, microvascular endothelial cell activation status was similar in both groups, except for a higher Ang-2 expression (P < 0.05) in the kidney of aged mice. Lipopolysaccharide-induced increase in neutrophil count was higher in old (3.3-fold change) compared with young mice (2.2-fold change). Messenger ribonucleic acid analysis showed higher upregulation of P- and E-selectin (P = 0.0004, P = 0.0007) after lipopolysaccharide administration in kidneys of elderly mice, which was confirmed at the protein level for E-selectin. Renal neutrophil influx in lipopolysaccharide-treated aged mice was increased (2.5-fold induction in aged and 2.1-fold in young, P < 0.0001). Polymorphonuclear cell depletion exaggerated the lipopolysaccharide-induced kidney injury. CONCLUSION: Ang-2 is increased in older mice, which might cause priming of the endothelial cells. Endothelium responded by a more extensive increase in expression of P- and E-selectin in older mice and increased polymorphonuclear cell influx.


Subject(s)
Acute Kidney Injury/chemically induced , Endothelial Cells/physiology , Lipopolysaccharides/toxicity , Neutrophils/physiology , Age Factors , Angiopoietin-2/genetics , Animals , E-Selectin/analysis , Female , Mice , Mice, Inbred C57BL , Microvessels/physiology , P-Selectin/analysis , Receptor, TIE-2/genetics
9.
Anesthesiology ; 115(3): 474-82, 2011 Sep.
Article in English | MEDLINE | ID: mdl-21778876

ABSTRACT

INTRODUCTION: The interaction between neutrophils and activated endothelium is essential for the development of multiple organ dysfunction in patients with hemorrhagic shock (HS). Mechanical ventilation frequently is used in patients with HS. The authors sought to investigate the consequences of mechanical ventilation of mice subjected to HS on microvascular endothelial activation in the lung and kidney. METHODS: Anesthetized wild type C57BL/6 male mice were subjected to controlled hemorrhage; subgroups of mice were mechanically ventilated during the HS insult. To study the effect of acute hypoxia on the mice, the animals were housed in hypoxic cages. Gene expression levels was assessed by quantitative real-time polymerase chain reaction. Protein expression was assessed by immunohistochemistry and enzyme-linked immunosorbent assay. RESULTS: Ninety minutes after the shock induction, a vascular bed-specific, heterogeneous proinflammatory endothelial activation represented by E-selectin, vascular cell adhesion molecule 1, and intercellular adhesion molecule 1 expression was seen in kidney and lung. No differences in adhesion molecules between the spontaneously breathing and mechanically ventilated mice were found. Concentrations of the proinflammatory cytokines chemokine (C-X-C motif) ligand 1 (11.0-fold) and interleukin-6 (21.7-fold) were increased after 90 min of HS. Two hours of 6% oxygen did not induce the expression of E-selectin, vascular cell adhesion molecule 1, and intercellular adhesion molecule 1 in the kidneys and the lung. CONCLUSIONS: Hemorrhagic shock leads to an early and reversible proinflammatory endothelial activation in kidney and lung. HS-induced endothelial activation is not changed by mechanical ventilation during the shock phase. Hypoxia alone does not lead to endothelial activation. The observed proinflammatory endothelial activation is mostly ischemia- or reperfusion-dependent and not related to hypoxia.


Subject(s)
Endothelial Cells/pathology , Hypoxia/pathology , Inflammation/pathology , Respiration, Artificial/adverse effects , Respiratory Mechanics/physiology , Shock, Hemorrhagic/pathology , Animals , Chemokine CX3CL1/metabolism , E-Selectin/metabolism , Enzyme-Linked Immunosorbent Assay , Gene Expression/drug effects , Immunohistochemistry , Intercellular Adhesion Molecule-1/metabolism , Male , Mice , Mice, Inbred C57BL , Microcirculation/drug effects , Oxygen/pharmacology , Platelet Endothelial Cell Adhesion Molecule-1/metabolism , Pulmonary Circulation/drug effects , Renal Circulation/drug effects , Reverse Transcriptase Polymerase Chain Reaction , Vascular Cell Adhesion Molecule-1/metabolism
10.
Anesthesiology ; 111(3): 600-8, 2009 Sep.
Article in English | MEDLINE | ID: mdl-19672168

ABSTRACT

BACKGROUND: Hemorrhagic shock is associated with changes in vascular responsiveness that may lead to organ dysfunction and, ultimately, multiple organ dysfunction syndrome. Volatile anesthetics interfere with vasoresponsiveness, which may contribute to organ hypoperfusion. In this study, the authors examined the influence of adjunct nitrous oxide on the vascular responsiveness after short-term hemorrhagic shock under isoflurane anesthesia. METHODS: Spontaneously breathing mice (n = 31, 27.6 +/- 0.31 g) were anesthetized with isoflurane (1.4%) or with isoflurane (1.4%) and adjunct nitrous oxide (66%). Both groups were divided into Sham, Shock, and Resuscitated groups. Vascular reactivity to phenylephrine and acetylcholine and expression of cyclooxygenases were studied in the aorta. RESULTS: In the isoflurane-anesthetized groups, the contractile response to phenylephrine was increased in the Shock as compared with the Sham and Resuscitated groups (Emax = 3.2 +/- 0.4, 1.2 +/- 0.4, and 2.5 +/- 0.5 mN, respectively). Adjunct nitrous oxide increased phenylephrine contraction to a similar level in all three groups. In the Sham isoflurane group, acetylcholine caused a biphasic response: An initial relaxation followed by a contractile response sensitive to cyclooxygenases inhibition by indomethacine. The contractile response was abrogated in the isoflurane-anesthetized groups that underwent shock. In all groups, adjunct nitrous oxide preserved the contractile phase. Shock induced a down-regulation of cyclooxygenases-1, which was normalized by adjunct nitrous oxide. CONCLUSION: Adjunct nitrous oxide attenuates shock-induced changes in vascular reactivity and cyclooxygenases expression of mice under isoflurane anesthesia. This implies that vascular reactive properties during anesthesia in hemorrhagic shock conditions may be influenced by the choice of anesthetics.


Subject(s)
Anesthesia, Inhalation , Anesthetics, Inhalation/therapeutic use , Blood Vessels/drug effects , Blood Vessels/physiopathology , Isoflurane , Nitrous Oxide/therapeutic use , Shock, Hemorrhagic/drug therapy , Shock, Hemorrhagic/physiopathology , Acetylcholine/pharmacology , Animals , Blood Gas Analysis , Blood Pressure/physiology , Blotting, Western , Cyclooxygenase 1/biosynthesis , Cyclooxygenase 2/biosynthesis , Mice , Muscle, Smooth, Vascular/drug effects , Muscle, Smooth, Vascular/physiology , Nitric Oxide Donors/pharmacology , Nitroprusside/pharmacology , Vasoconstriction/drug effects , Vasodilator Agents/pharmacology
11.
Anesthesiology ; 98(1): 133-42, 2003 Jan.
Article in English | MEDLINE | ID: mdl-12502989

ABSTRACT

BACKGROUND: In myasthenic patients, the sensitivity for nondepolarizing relaxants is increased and the time course of effect is prolonged due to a reduced number of functional acetylcholine receptors at the neuromuscular junction. The authors investigated both the performance of the link model proposed by Sheiner and a pharmacodynamic-pharmacokinetic model taking into account the number of unbound acetylcholine receptors in myasthenic pigs. METHODS: After obtaining the approval of the Animal Experiments Committee of their institution, the authors studied eight myasthenic pigs and eight control pigs. Myasthenia gravis was induced by injecting Torpedo acetylcholine receptors in weeks 1 and 4. On the day of the experiments, the pigs were anesthetized and intubated, and the appropriate muscles and nerves were prepared for the measurements. Rocuronium was administered by infusion to reach 90% twitch height block. Arterial blood was sampled during onset and offset of effect, and the plasma concentration of rocuronium was measured with high-performance liquid chromatography. Plasma concentration-time effect data were analyzed using two different pharmacokinetic-pharmacodynamic models, the link model according to Sheiner and a pharmacokinetic-pharmacodynamic model taking into account the unbound receptor concentration. Muscles were removed after the experiment for laboratory analysis of the acetylcholine receptor concentration. RESULTS: All eight pigs of the myasthenic group developed clinical signs of myasthenia gravis (muscle weakness) and showed increased sensitivity toward rocuronium. Pharmacokinetic modeling revealed no significant differences between myasthenic and control pigs. In pharmacokinetic-pharmacodynamic analysis, visual inspection as well as the Akaike Information Criterion (3,605 3,769) and the residual SD (3.2 3.6%) revealed a better fit for the unbound receptor model in myasthenic animals compared to the Sheiner model. Pharmacokinetic-pharmacodynamic analysis with the unbound receptor model demonstrated a decreased EC50 of 0.27 micro m (ranging from 0.17 to 0.59 micro m) compared to 2.71 micro m (ranging from 2.42 to 4.43 micro m) in control animals. The results of the Sheiner pharmacokinetic-pharmacodynamic analysis were in the same range. Both the laboratory analysis and pharmacokinetic-pharmacodynamic modeling showed a decrease in receptor concentration of more than 75%. CONCLUSION: Both the Sheiner model and the unbound receptor model may be used to fit plasma concentration-effect data of rocuronium in pigs. The unbound receptor concentration model, however, can explain the observed differences in the time course of effect, based on receptor concentration.


Subject(s)
Androstanols/pharmacology , Androstanols/pharmacokinetics , Neuromuscular Nondepolarizing Agents/pharmacology , Neuromuscular Nondepolarizing Agents/pharmacokinetics , Receptors, Cholinergic/drug effects , Algorithms , Androstanols/blood , Animals , Female , Immunohistochemistry , Models, Biological , Myasthenia Gravis, Autoimmune, Experimental/metabolism , Neuromuscular Junction/drug effects , Neuromuscular Junction/metabolism , Neuromuscular Nondepolarizing Agents/blood , Receptors, Cholinergic/immunology , Rocuronium , Swine , Torpedo
12.
Anesthesiology ; 96(4): 963-70, 2002 Apr.
Article in English | MEDLINE | ID: mdl-11964606

ABSTRACT

BACKGROUND: A model of an antegrade, perfused, isolated rat peroneal nerve anterior tibial muscle was developed to study potentially important factors governing the time course of action of (nondepolarizing) neuromuscular blocking agents such as concentration, blood flow, and temperature. The model allows observation of the effects of selective changes in these factors. METHODS: The authors isolated the anterior tibial muscle and cannulated the anterior tibial artery and vein, providing a way for single-pass perfusion with blood from a donor rat. A force transducer was connected to the tibialis anterior muscle and a stimulator was connected to the tibial nerve. The influence of intrinsic potency (EC90) and muscle blood flow rate on the time course of pancuronium and rocuronium was investigated. RESULTS: The model remained stable for at least 4 h with respect to twitch height, muscle structure and function, and blood chemistry. Doubling the muscle-blood flow resulted in a significantly faster onset and offset for both pancuronium and rocuronium. Trebling the intrinsic potency (EC90) was not associated with significant changes in the time course of action of the relaxants. CONCLUSION: The authors developed and validated a model that allows us to study biophase kinetics of neuromuscular blocking agents in the anterior tibial muscle of the rat. In this model, muscle-blood flow rather than EC90 appears to predominantly determine the onset and offset time of nondepolarizing muscle relaxants.


Subject(s)
Neuromuscular Blocking Agents/pharmacology , Neuromuscular Junction/drug effects , Peroneal Nerve/drug effects , Androstanols/pharmacology , Animals , Male , Neuromuscular Blocking Agents/pharmacokinetics , Neuromuscular Junction/physiology , Pancuronium/pharmacology , Perfusion , Rats , Rats, Wistar , Regional Blood Flow , Rocuronium , Tibia
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