[Influence of atracurium on cardiovascular parameters in horses undergoing vitrectomy during general anaesthesia, and on recovery duration and quality]

OBJECTIVE

In most ocular procedures, a central position of the eye is necessary. This can be achieved using a deep plane of anaesthesia, locoregional blocks or with neuromuscular blocking agents. The aim of this study was to evaluate the influence of atracurium on cardiovascular parameters, and on recovery quality and duration in horses.

MATERIAL AND METHODS

Thirty-four warmblood horses undergoing in total 50 vitrectomies were divided into two groups. Premedication, induction and maintenance were identical in all patients. After 20 minutes, horses of group A received atracurium (0.1 mg/kg) while in the control group (group K) the depth of anaesthesia was adapted to keep the bulbus in a central position. Dobutamine and fluids were administered to maintain the mean arterial blood pressure (MAP) above 70 mmHg. Cardiac output (CO), heart rate (HR), MAP, respiratory rate, end-expiratory isoflurane concentration (ETIso) and dobutamine requirements were determined. Position and movement of the globe during the surgical procedure were scored. Time and quality of the recovery period was scored.

RESULTS

Horses of group K required significantly higher concentrations of isoflurane (group A: 1.08 ± 0.1%; group K: 1.34 ± 0.2%) and had an overall lower MAP (group A: 88.4 ± 10.3 mmHg; group K: 76.6 ± 11.6 mmHg) and CO (group A: 36.9 ± 11.7 l/min; group K: 28.5 ± 7.2 l/min) but needed significantly more dobutamine (group A: 0.37 ± 0.17 μg/kg/min; group K: 0.99 ± 0.46 μg/kg/min) compared to group A. Complete relaxation occurred 9.5 ± 2.5 minutes after atracurium bolus and lasted for 25 ± 7.1 minutes. The score of the bulbus position and movement was significantly lower in group A, resulting in a better quality for the surgical procedure. In group A, the recovery time to standing was significantly shorter (group A: 18.1 ± 5.4 min; group K: 31.5 ± 7.1 min), with no difference in quality.

CONCLUSION AND CLINICAL RELEVANCE

The use of atracurium resulted in a better cardiovascular condition, probably because of the isoflurane-sparing effect. The recovery time was shorter in these horses without negative effects on recovery quality. No signs of residual atracurium effects were detected.

Einsatz von Atracurium bei der Vitrektomie des Pferdes

Gegenstand und Ziel: Eingriffe am Auge erfordern einen zentral und ruhig liegenden Bulbus, der sich mittels sehr tiefer Narkose, regionalanästhetischer Techniken oder peripherer Muskelrelaxanzien erreichen lässt. Ziel der Studie war, den Einfluss des peripheren Muskelrelaxans Atracurium auf den Relaxationsgrad der okulären Muskulatur, intraoperative Kreislaufparameter sowie Qualität und Dauer der Aufstehphase zu evaluieren. Material und Methoden: Die Untersuchung erfolgte an 34 Pferden (insgesamt 50 Vitrektomien), die randomisiert zwei Gruppen (je n = 17) zugeteilt wurden. Narkoseprämedikation, -induktion und -erhaltung waren identisch. Nach 20 Minuten wurde Pferden der Gruppe A Atracurium appliziert (0,1 mg/kg i. v.) und die Dauer der neuromuskulären Blockade mittels Nervenstimulator überwacht. In der Kontrollgruppe (Gruppe K) wurde bei Bedarf zur Relaxation der okulären Muskeln die Isoflurankonzentration erhöht. Die Applikation von Dobutamin erfolgte nach Wirkung, um einen mittleren arteriellen Blutdruck (MAP) von mindestens 70 mmHg zu erhalten. Folgende Parameter wurden ausgewertet: Herz- und Atemfrequenz, endexspiratorische Isoflurankonzentration (ETIso), MAP, Herzminutenvolumen (HMV), arterielle Blutgase, Dobutaminverbrauch, Dauer und Qualität der Aufstehphase. Zur Erfassung von Bulbusposition und -bewegung diente ein Score. Ergebnisse: In Gruppe K war für einen MAP von 76,6 ± 11,6 mmHg eine Dobutamindosis von 0,99 ± 0,46 μg/kg/min notwendig, in Gruppe A für einen MAP von 88,4 ± 10,3 mmHg 0,37 ± 0,17 μg/kg/min. Das durchschnittliche HMV betrug in Gruppe K 28,5 ± 7,2 l/min, in Gruppe A 36,9 ± 11,7 l/min. Dobutaminverbrauch und HMV differierten signifikant. Der mittlere ETISO war in Gruppe K mit 1,34 ± 0,16 Vol% signifikant höher als in Gruppe A mit 1,08 ± 0,1 Vol%. Innerhalb von 9,5 ± 2,5 Minuten nach Atracuriumgabe waren alle Pferde für 25 ± 7,5 Minuten vollständig relaxiert. Der Bulbus lag bis Operationsende zentral. Die Aufstehphase dauerte in Gruppe K signifikant länger als in Gruppe A (31,5 ± 7,1 vs. 18,1 ± 5,4 Minuten). Schlussfolgerung und klinische Relevanz: Eine Muskelrelaxation mit Atracurium erlaubt eine Einsparung von Inhalationsanästhetikum mit deutlich verbesserten Kreislaufparametern während der Vitrektomie. Neuromuskuläre Restblockaden konnten nicht beobachtet werden.

[Computed tomography diagnosis of a retrobulbar abscess in a white tiger]

SUBJECT

Etiologic diagnosis of a retrobulbar process is essential for the initiation of a causative therapy. Penetrating foreign bodies and tooth root abscesses, but also neoplastic processes have to be considered as a differential diagnosis for a retrobulbar swelling. The objective of this case report of a tiger with a retrobulbar process was to demonstrate the diagnostic value of computed tomography for making a causative diagnosis.

MATERIAL AND METHODS

General examination of the tiger as well as subsequent computed tomography and surgical extraction of a fractured fourth premolar tooth of the left upper jaw was carried out under general anaesthesia. Collected alveolar tissue samples underwent cytological, histopathological and microbiological analyses.

RESULTS AND CLINICAL RELEVANCE

Computed tomography was able to allocate the origin of the retrobulbar abscess to the left 4th premolar tooth of the upper jaw. The cytological, histopathological and microbiological examination of the recovered alveolar material confirmed the diagnosis of purulent-necrotic abscess-forming inflammation as a result of a mixed bacterial infection. The present case report demonstrates the diagnostic accuracy of computed tomography for the diagnosis of a retrobulbar process of unknown origin.

Chiari Malformation Type I with Concomitant Persistent Trigeminal Artery

BACKGROUND

Chiari malformation type I is a stenosis of the subarachnoid space at the level of the foramen magnum due to a small posterior fossa and herniation of the cerebellar tonsils. We present here the unusual case of a Chiari malformation in conjunction with a persistent trigeminal artery and hypoplasia of the basilar artery, also known as a Saltzman anomaly.

CASE REPORT

A 34-year-old female physician presented with recurrent headaches, bilateral weakness of deltoid muscles and numbness of the fingertips 3 to 5. A cranial MRI revealed a descent of the cerebellar tonsils to the level of C2 and a supracerebellar cyst. During surgery, a decompressive suboccipital craniectomy was performed. The supracerebellar cyst was fenestrated and the cerebellar tonsils were resected bilaterally. Two days after surgery the patient developed cranial nerve dysfunction and a right-sided hemiparesis. Cerebral angiography revealed a Saltzman type 1 anomaly with persistent primitive trigeminal artery and hypoplasia of the basilar artery.

DISCUSSION

This is the first report in the literature about the coincidence of both unusual anomalies. The latest literature of both rare anatomy and the unusual clinical course will be discussed.

Endothelin-1 in plasma, cisternal CSF and microdialysate following aneurysmal SAH

OBJECTIVE

Endothelin-1 (ET-1) is postulated to play an important role in the development of cerebral vasospasm (CVS) following SAH. This study was conducted to investigate the time course of ET-release in three different sources: CSF, plasma and microdialysate.

METHODS

In a prospective study ET-1-concentrations were measured in plasma, cisternal CSF and microdialysate in 20 patients with aneurysmal SAH for at least 8 days after hemorrhage.

RESULTS

ET-1 concentration in microdialysate was almost four times higher compared to CSF and plasma. (p<0.001) Only in CSF ET-1-release showed a significant increase over time with highest values on day 5 post ictus (p = 0.03). This was parallel to the increase of transcranial Doppler velocities. ET-1 in plasma and microdialysate did not change over time.

CONCLUSION

ET-1 may have a different biological function in different biological tissues. Only ET-1 in CSF seemed to be associated with CVS.

Closure of large patent ductus arteriosus with a self-expanding duct occluder in two dogs

Of the different catheterisation methods described for closure of patent ductus arteriosus (PDA), coil embolisation is most commonly used in dogs. However, for a PDA larger than 4 to 5 mm in diameter, coil implantation is difficult. For these cases, the Amplatzer duct occluder (ADO) offers an alternative method. This report describes the successful implantation of an ADO in two dogs with large PDAs of approximately 6 mm diameter. The self-expandible device attached to an implantation wire was advanced through a long sheath antegrade to the femoral vein through the right heart and pulmonary artery to the duct and delivered into the PDA. Thereafter the device was released by unscrewing it from the delivery cable. The large PDA in both dogs was totally occluded by these means without any residual shunt. Thus, the ADO is a controlled release implant that also allows occlusion of a large PDA. Its high costs limit its general use in veterinary medicine at the present time.

[Delayed traumatic CSF-fistulas: a retrospective analysis]

Immediate posttraumatic CSF-fistulas are a well known entity after severe head injury. Delayed onset of rhinorrhea is considered to be rare. In the last 5 years 7 patients were treated in our department, who developed rhinorrhea 2-25 years after trauma. All patients went through episodes of meningitis. In 4 cases intermittent rhinorrhea was reported. In all cases a bony defect of the anterior skull base was detected by coronal bone window CT-scan. In three of them an encephalocele was revealed by MR-scanning. Treatment consisted in reconstruction of anterior skull base with a pedicled galeal-pericranial flap via a bifrontal craniotomy and went out without any complications. Delayed rhinorrhea after severe head injury is not a rare curiosity. In cases of bony defects after head injury reconstruction of anterior skull base is recommended to prevent episodes of recurrent meningitis.

[Delayed appearance of posttraumatic cerebrospinal fluid fistulas as a cause of recurrent meningitis]

Immediate post-traumatic fistulas with rhinorrhea are well known after head injury with frontobasal trauma. Less attention is paid to the possibility of delayed onset of rhinorrhea after severe head injury. Unrecognised frontobasal injury may cause recurrent meningitis due to communication of CSF with the outside world. In the last 5 years, seven patients who developed rhinorrhea 2-25 years after trauma were treated in our department. All patients had been through at least two episodes of meningitis. Intermittent rhinorrhea was reported by four. In all cases, coronal bone window CT scan disclosed a bony defect of the anterior skull base, and in three cases an encephalocele was revealed on MRI. Treatment consisted of reconstruction of the anterior skull base with a pedicled galeal-pericranial flap via bifrontal craniotomy. Delayed traumatic CSF fistulas are not rare but must be considered in the differential diagnosis of recurrent meningitis.

Gene expression patterns of the fibroblast growth factors and their receptors during myogenesis of rat satellite cells

Satellite cells are the myogenic precursors in postnatal muscle and are situated beneath the myofiber basement membrane. We previously showed that fibroblast growth factor 2 (FGF2, basic FGF) stimulates a greater number of satellite cells to enter the cell cycle but does not modify the overall schedule of a short proliferative phase and a rapid transition to the differentiated state as the satellite cells undergo myogenesis in isolated myofibers. In this study we investigated whether other members of the FGF family can maintain the proliferative state of the satellite cells in rat myofiber cultures. We show that FGF1, FGF4, and FGF6 (as well as hepatocyte growth factor, HGF) enhance satellite cell proliferation to a similar degree as that seen with FGF2, whereas FGF5 and FGF7 are ineffective. None of the growth factors prolongs the proliferative phase or delays the transition of the satellite cells to the differentiating, myogenin(+) state. However, FGF6 retards the rapid exit of the cells from the myogenin(+) state that routinely occurs in myofiber cultures. To determine which of the above growth factors might be involved in regulating satellite cells in vivo, we examined their mRNA expression patterns in cultured rat myofibers using RT-PCR. The expression of all growth factors, excluding FGF4, was confirmed. Only FGF6 was expressed at a higher level in the isolated myofibers and not in the connective tissue cells surrounding the myofibers or in satellite cells dissociated away from the muscle. By Western blot analysis, we also demonstrated the presence of FGF6 protein in the skeletal musle tissue. Our studies therefore suggest that the myofibers serve as the main source for the muscle FGF6 in vivo. We also used RT-PCR to analyze the expression patterns of the four tyrosine kinase FGF receptors (FGFR1-FGFR4) and of the HGF receptor (c-met) in the myofiber cultures. Depending on the time in culture, expression of all receptors was detected, with FGFR2 and FGFR3 expressed only at a low level. Only FGFR4 was expressed at a higher level in the myofibers but not the connective tissue cell cultures. FGFR4 was also expressed at a higher level in satellite cells compared to the nonmyogenic cells when the two cell populations were released from the muscle tissue and fractionated by Percoll density centrifugation. The unique localization patterns of FGF6 and FGFR4 may reflect specific roles for these members of the FGF signaling complex during myogenesis in adult skeletal muscle.

Expression, activity and functional significance of inducible nitric oxide synthase in the failing human heart

OBJECTIVES

The study was designed to evaluate the functional impact of nitric oxide (NO) generation within the myocardium on cardiac contraction in the failing human heart.

BACKGROUND

Heart failure is associated with activation of cytokines and expression of inducible nitric oxide synthase (NOS II), which generates NO from L-arginine. Nitric oxide has been shown to modulate myocardial performance, raising the possibility that cardiac generation of NO by NOS II modulates cardiac contraction in the failing human heart.

METHODS

Left ventricular (LV) tissue of 24 patients with end-stage heart failure was obtained during cardiac transplantation. Gene expression of NOS II and endothelial NO-synthase (NOS III) was quantified by competitive reverse transcription-polymerase chain reaction and compared to tissues of five nonfailing donor hearts. Nitric oxide synthase II activity was determined by citrulline assay and related to changes in force of contraction induced by the beta-adrenergic agonist isoproterenol, NO-donors and/or N-mono-methyl-L-arginine (L-NMMA), an inhibitor of NOS.

RESULTS

While NOS III mRNA was reduced in failing hearts, NOS II mRNA was increased in failing LV tissue and correlated with NOS II activity. High NOS II activity was associated with early relaxation and impaired responsiveness to beta-adrenergic stimulation, that is, the inotropic response to isoproterenol in failing hearts was inversely related to NOS II activity (r=0.61, p < 0.005). Nitric oxide donors or L-NMMA did not affect myocardial performance in failing hearts at baseline. However, L-NMMA enhanced the positive inotropic response to beta-adrenergic stimulation in failing hearts with high NOS II activity. Nitric oxide donors attenuated the isoproterenol-induced increase in force of contraction of failing hearts.

CONCLUSIONS

Cardiac production of NO by NOS II attenuates the positive inotropic effects of beta-adrenergic stimulation and hastens relaxation in failing human hearts.

NAD(P)H oxidase activity in cultured human podocytes: effects of adenosine triphosphate

Reactive oxygen species contribute to glomerular damage and proteinuria. In this study, we show that cultured human podocytes produce superoxide in response to extracellular adenosine triphosphate (ATP), and we identified the oxidases involved in this process. Adenosine triphosphate (10-4 M for 4 hr) raised superoxide production from 1.28 +/- 0.15 to 2.67 &/- 0.34 nmol/mg protein/min. Studies with podocyte homogenates revealed activation of both nicotinamide adenine dinucleotide (NADH; from 2.65 +/- 0.23 to 7.43 +/- 0.57) and nicotinamide adenine dinucleotide phosphate (NADPH) dependent oxidases [from 1.74 +/- 0.13 to 4.05 +/- 0.12 (nmol O2/mg protein/min)] by ATP. Activity of xanthine-oxidases was low and unchanged by ATP. Activation of the plasma-membrane bound NAD(P)H oxidases by ATP was time and dose dependent. Reverse transcribed-polymerase chain reaction (RT-PCR) studies with primers derived from monocyte sequences amplified mRNA for the NADPH oxidase subunits p22phox, p47phox, gp91phox, and p67phox, and the latter was transiently increased by ATP. Experiments with actinomycin D and cycloheximide suggested that ATP modulates enzyme activity at the transcriptional and translational levels. In conclusion, NAD(P)H dependent, membrane associated oxidases represent the major superoxide source in human podocytes. Activation of NAD(P)H oxidase by ATP might be secondary to increased mRNA expression of the NADPH oxidase subunit gp67phox.

Left ventricular contractile effects of inducible nitric oxide synthase in the human allograft

BACKGROUND

Myocardial expression of inducible (i) nitric oxide (NO) synthase (iNOS) gene has been reported in transplant recipients and in dilated cardiomyopathy. NO derived from NO donor or from coronary endothelium has previously been shown in the human heart to reduce end-systolic left ventricular (LV) pressure, especially during beta-adrenoreceptor stimulation, because of earlier onset of LV relaxation. The present study investigated in transplant recipients whether a similar cardiodepressant effect could be attributed to NO derived from iNOS.

METHODS AND RESULTS

In 16 transplant recipients who were free of rejection or graft vasculopathy, microtip LV pressure recordings, LV angiograms, and endomyocardial biopsies were obtained at annual coronary angiography. In 8 transplant recipients, microtip LV pressure recordings were obtained during intravenous dobutamine (5 microg x kg(-1) x min(-1)). Competitive reverse transcription-polymerase chain reaction of iNOS mRNA was performed on the endomyocardial biopsies, and the intensity of iNOS mRNA expression was quantified on a scale ranging from 0 to 5+. All measures of baseline LV function were comparable in transplant recipients with low (< or = 2+) or high myocardial iNOS mRNA. During intravenous dobutamine infusion, there was a significant correlation between the abbreviation of LV electromechanical systole time (LVEST is the time from onset of QRS to dP/dt(min)) and the rise of LV dP/dt(max) (r=.79; P<.02). By use of a multiple regression analysis, addition of the intensity of iNOS mRNA expression as an independent variable significantly (P<.005) improved the correlation between deltaLVEST and deltaLV dP/dt(max) (P<.001; r=.97), implying a larger abbreviation of LV contraction for a similar rise in LV dP/dt(max), when myocardial iNOS mRNA was higher. The larger abbreviation of LV contraction in-patients with high iNOS mRNA was associated with a decrease in LV end-systolic pressure (-31+/-16 mm Hg).

CONCLUSIONS

Myocardial iNOS gene expression in the human allograft influences the LV contractile response to beta-adrenergic stimulation through earlier onset of LV relaxation and reduction of LV end-systolic pressure. These effects are similar to the LV contractile effects of NO derived from NO donor or from coronary endothelium.

Myocardial contractile effects of L-arginine in the human allograft

OBJECTIVES

In the present study, we investigated, in transplant recipients, whether L-arginine (L-arg) potentiates the myocardial contractile effects of receptor-mediated coronary endothelial stimulation. Moreover, because inducible nitric oxide synthase (iNOS) is frequently expressed in transplanted myocardium, we also performed intracoronary infusion of L-arg in the absence of receptor-mediated coronary endothelial stimulation to investigate whether similar left ventricular (LV) contractile effects could be induced by providing more substrate for iNOS.

BACKGROUND

Nitric oxide (NO), released from coronary endothelium after receptor-mediated stimulation by substance P (SP), affects vascular smooth muscle tone and modulates LV contractile performance. L-arg augments receptor-mediated endothelium-dependent coronary vasodilation in transplant recipients by increasing substrate availability for endothelial NO production.

METHODS

Sixteen transplant recipients were studied at the time of annual coronary angiography. In eight transplant recipients, microtip LV pressures were recorded before and during intracoronary (IC) SP (20 pmol/min) and after the addition of IC L-arg (160 mumol/min) to IC SP. In eight transplant recipients, microtip LV pressures were recorded before and during IC L-arg (160 mumol/min) alone, and in six of these patients, endomyocardial biopsy samples were obtained to detect the expression of iNOS gene by reverse transcription-polymerase chain reaction.

RESULTS

Addition of IC L-arg to IC SP induced a fall (mean +/- SEM) in LV peak systolic pressure (-16 +/- 4 mm Hg), which was larger (p < 0.01) than that observed during IC SP (-7 +/- 2 mm Hg). During IC L-arg alone, there was no change in LV peak systolic pressure despite the presence of iNOS mRNA in five of the six biopsy samples.

CONCLUSIONS

In transplant recipients, L-arg potentiates the paracrine myocardial contractile effects of receptor-mediated coronary endothelial stimulation, probably by providing more substrate for endothelial NO production. Despite the myocardial expression of iNOS gene, L-arg alone fails to elicit similar contractile effects.

Left ventricular wall stress and sarcoplasmic reticulum Ca(2+)-ATPase gene expression in renal hypertensive rats: dose-dependent effects of ACE inhibition and AT1-receptor blockade

BACKGROUND

Cardiac hypertrophy is associated with altered Ca2+ handling and may predispose to the development of LV dysfunction and cardiac failure. At the cellular level, the re-expression of ANF represents a well-established marker of myocyte hypertrophy while the decreased expression of the sarcoplasmatic reticulum (SR) Ca(2+)-ATPase is thought o play a crucial role in the alterations of Ca2+ handling and LV function. We assessed the dose-dependent effect of chronic ACE inhibition or AT1 receptor blockade on cardiac function in relation to the cardiac expression of the SR Ca(2+)-ATPase and ANF.

METHODS AND RESULTS

Renal hypertensive rats (2K-1C) were treated for 12 weeks with three different doses of the ACE inhibitor benazepril, the AT1-receptor antagonist valsartan (each drug 0.3, 3, and 10 mg/kg per day i.p.) or placebo. LV dimensions, hypertrophy and wall stress were determined in vivo by magnetic resonance imaging and the gene expressions of ANF and SR Ca(2+)-ATPase were quantified by Northern blot. Low doses of both drugs did not affect blood pressure, hypertrophy, systolic wall stress and the ANF and SR Ca(2+)-ATPase gene expression. High doses of each drug reduced systolic blood pressure, wall stress, and LV hypertrophy to a similar extent and to values comparable to normotensive, age-matched rats. In addition, high dose treatment reduced LV end-systolic and end-diastolic volume as compared to untreated 2K-1C animals and normalized the mRNA levels of both ANF and SR Ca(2+)-ATPase (as compared to normotensive animals).

CONCLUSIONS

We conclude that in this model, high doses of ACE inhibition and AT1-receptor blockade are necessary to normalize systolic blood pressure, LV hypertrophy and systolic LV wall stress which, in turn, is associated with restoration of a normal cardiac phenotype with respect to SR Ca(2+)-ATPase and ANF and normalization of cardiac function.

Virus-vs endotoxin-induced activation of liver macrophages

The response of liver macrophages (Kupffer cells) to distinct pathogenic material was investigated by comparing virus- and endotoxin-induced macrophage activation. Endotoxin-induced stimulation and induction with Newcastle disease virus (NDV) or Sendai virus led to the release of the same pattern of prostanoids characterized by a predominant production of prostaglandin E2 (PGE2). With respect to peptide mediators, hepatic macrophages secreted tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 after viral induction and endotoxin treatment, respectively. In response to viruses, however, much more interleukin-6 and TNF-alpha was detected than after endotoxin stimulation. Interferon type I (interferon-alpha/beta), on the other hand, was only detected in the supernatants of macrophages infected with viruses, but not of those exposed to endotoxin. This study also revealed that rat TNF-alpha exists in several soluble species, some of which are glycosylated.

Prevention of endogenous leukotriene production during anaphylaxis in the guinea pig by an inhibitor of leukotriene biosynthesis (MK-886) but not by dexamethasone

Leukotriene C4 (LTC4) underwent rapid elimination from the circulating blood and was extensively converted to LTD4 within the vascular space of the guinea pig. To mimic the elimination and metabolism of endogenous LTC4 generated during anaphylaxis, 14,15-3H-labeled LTC4 was infused intravenously over a period of 15 min, leading to a recovery in bile of 85% of the infused LT radioactivity within 2 h. Corresponding to the tracer studies, LTD4 and, to a lesser extent, LTC4 were the predominant endogenous cysteinyl LTs in guinea pig bile. The biliary production rate of endogenous LTD4 increased from 0.3 +/- 0.1 to 6.2 +/- 1.8 pmol x min-1 x kg-1 (p less than 0.001) during anaphylactic shock induced by intravenous injection of OVA (0.2 mg/kg) into sensitized guinea pigs. A novel LT biosynthesis inhibitor (MK-886; 10 mg/kg, i.v., 15 min before antigen challenge) suppressed the antigen-induced cysteinyl LT production by greater than 92% (p less than 0.001). This inhibition of systemic LTC4 formation was associated with a complete protection against lethal anaphylactic shock in animals pretreated in addition with the H1 receptor antagonist pyrilamine. Pretreatment with either the inhibitor of LT synthesis or the histamine receptor antagonist reduced the lethality during anaphylactic shock from 100 to 60 and 78%, respectively. In artificially ventilated, pyrilamine-pretreated animals, the antigen-induced decrease in dynamic lung compliance and the rise in hematocrit were significantly reduced (p less than 0.05) by pretreatment with the inhibitor of LT synthesis. Dexamethasone at high doses (10 mg/kg, i.p., once daily for 7 d, or in a single dose of 10 mg/kg, i.v., 3.5 h before challenge) had no inhibitory effect on LT generation during anaphylaxis in vivo. However, in resident peritoneal macrophages, harvested from these dexamethasone-treated sensitized guinea pigs and stimulated with zymosan, both cysteinyl LT and 6-keto-PGF1 alpha formation were strongly suppressed. These studies indicate an important role of cysteinyl LTs in systemic anaphylaxis in vivo and demonstrate the blockade of anaphylactic LT generation by a novel inhibitor of LT biosynthesis (MK-886) but not by dexamethasone.

Analysis of cysteinyl leukotrienes in human urine: enhanced excretion in patients with liver cirrhosis and hepatorenal syndrome

The cysteinyl leukotrienes, comprising leukotriene C4 and its metabolites, are biologically most active mediators, eliminated from the blood circulation by the liver and the kidneys. The urine of normal subjects and of patients with hepatic and/or renal failure was analysed for endogenous cysteinyl leukotrienes. The leukotriene metabolites were separated by reversed-phase high-performance liquid chromatography and subsequently quantified by radioimmunoassay. Leukotriene E4 was detected in all urine samples analysed. Its mean concentration increased from 0.3 nmol l-1 in healthy subjects to 0.8 nmol l-1 in patients with liver cirrhosis. In patients with hepatorenal syndrome leukotriene E4 averaged 7.8 nmol l-1; in addition, N-acetyl-leukotriene E4 was detected in an average amount of 1.5 nmol l-1. The mean leukotriene E4/creatinine ratio in urine increased from 0.02 in healthy subjects to 0.11 in patients with liver cirrhosis and to 1.2 mumol leukotriene E4 mol-1 creatinine in patients with hepatorenal syndrome. These results indicate that cysteinyl leukotrienes may play an important role in the mediator network responsible for the development of the hepatorenal syndrome in patients with severe liver disease.