Porcine hepatocyte-Kupffer cell co-culture as an in vitro model for testing the efficacy of anti-inflammatory substances.

As Kupffer cells are highly involved in the regulation of hepatic inflammatory response, the main goal of this study was to improve and to characterize a hepatocyte-Kupffer cell co-culture of pig origin for modelling endotoxin-induced hepatic inflammation and for testing the efficacy of potential anti-inflammatory substances. This monolayer co-culture was prepared from primary isolated swine hepatocytes and Kupffer cells in the ratio of 6:1 and 2:1, mimicking different states of liver inflammation. The prepared cell cultures were characterized by immunohistochemical CD-68 detection. Lipopolysaccharide (LPS) challenge of both co-cultures resulted in elevated interleukin-8 (IL-8) and that of 6:1 co-cultures in increased IL-6 production with a higher extent than on hepatocyte monocultures, justifying the key role of Kupffer cells in pro-inflammatory cytokine production. LPS-induced IL-8 production was successfully attenuated by concomitant application of both sodium butyrate and terpinen-4-ol on hepatocyte monocultures, but not on co-cultures, demonstrating the importance of the presence of Kupffer cells in cell cultures as inflammatory models. Based on these initial data, the applied porcine primary hepatocyte-Kupffer cell co-culture is suggested to be a proper tool for in vitro investigations on liver physiology and hepatic inflammation in pigs and can be used as a useful model mimicking in vivo conditions in veterinary research.

Feed-drug interaction of orally applied butyrate and phenobarbital on hepatic cytochrome P450 activity in chickens.

The expression of hepatic drug-metabolizing cytochrome P450 (CYP) enzymes may be affected by several nutrition-derived compounds, such as by the commonly applied feed additive butyrate, possibly leading to feed-drug interactions. The aim of this study was to provide some evidence if butyrate can alter the activity of hepatic CYPs in chickens exposed to CYP-inducing xenobiotics, monitoring for the first time the possibility of such interaction. Ross 308 chickens in the grower phase were treated with daily intracoelomal phenobarbital (PB) injection (80 mg/kg BW), applied as a non-specific CYP-inducer, simultaneously with two different doses of intra-ingluvial sodium butyrate boluses (0.25 and 1.25 g/kg BW) for 5 days. Activity of CYP2H and CYP3A subfamilies was assessed by specific enzyme assays from isolated liver microsomes. According to our results, the lower dose of orally administered butyrate significantly attenuated the PB-triggered elevation of both hepatic CYP2H and CYP3A activities, which might be in association with the partly common signalling pathways of butyrate and CYP-inducing drugs, such as that of PB. Based on these data, butyrate may take part in pharmacoepigenetic interactions with simultaneously applied drugs or other CYP-inducing xenobiotics, with possible consequences for food safety and pharmacotherapy. Butyrate was found to be capable to maintain physiological CYP activity by attenuating CYP induction, underlining the safety of butyrate application in poultry nutrition.

Effects of oral butyrate application on insulin signaling in various tissues of chickens.

The influence of butyrate on insulin signaling in chickens was studied because butyrate is produced during microbial fermentation in the large intestine of birds, and butyrate is widely used as a feed additive in animal production. Ross 308 broiler chickens received a daily intraingluvial bolus of sodium butyrate (0.25 g/kg body weight) on days 20-24 of life (n = 10). Plasma butyrate concentration increased after receiving oral butyrate treatment (P < 0.001). Oral butyrate application was associated with decreased protein expression of insulin receptor ß subunit (IRß) in liver (P = 0.008) and both abdominal (P = 0.003) and subcutaneous adipose tissue (P < 0.001), but with elevated IRß expression in muscle (P = 0.045), assessed by Western blotting. The quantity of hepatic phosphatidyl-inositol-3-kinase was reduced in the butyrate-treated group (P = 0.007); further, mammalian target of rapamycin was downregulated by butyrate in liver (P < 0.001) and subcutaneous adipose tissue (P = 0.038). Oral butyrate application provoked reduced systemic insulin sensitivity in chickens, indicated by elevated fasting blood glucose and subsequently, insulin level. However, responses of insulin signaling cascade to butyrate were tissue specific, suggesting that butyrate could act on glucose shifting among tissues by selectively increasing the glucose uptake of skeletal muscle via IRß upregulation.

Effects of Lactobacillus plantarum 2142 and sodium n-butyrate in lipopolysaccharide-triggered inflammation: comparison of a porcine intestinal epithelial cell line and primary hepatocyte monocultures with a porcine enterohepatic co-culture system.

This study was based on our previously developed double-layered enterohepatic co-culture system, composed of nontumorigenic porcine intestinal epithelial cell line (IPEC-J2) and primary culture of porcine hepatocytes. The anti-inflammatory effect of spent culture supernatant of Lactobacillus plantarum 2142 (Lp2142; 13.3%) and sodium n-butyrate (2 mM) was tested on IPEC-J2 and hepatocyte monocultures as well as on the gut-liver co-culture. To mimic inflammation, lipopolysaccharide (LPS; 1 and 10 µg/mL) was applied. Production of IL-8 and IL-6 was measured as a marker of inflammatory responses. The paracellular permeability of the intestinal epithelium was also monitored by fluoresceinisothiocyanate-labeled dextran 4 assay. Significant increase of IL-8 concentration was observed in the IPEC-J2 monoculture (P < 0.01) while the level of IL-6 was not changed following LPS treatment. Concentration of IL-8 and IL-6 was grown significantly in hepatocyte monocultures (P < 0.05 and P < 0.001) as well as in the co-culture after 10 µg/mL LPS treatment (P < 0.001 and P < 0.001). One microgram per milliliter LPS caused elevated IL-8 level in the co-culture (P < 0.001) and in the hepatocyte monoculture (P < 0.01), while it caused increased IL-6 level only in the hepatocytes (P < 0.001). Production of IL-8 was significantly decreased by butyrate in case of 1 µg/mL as well as 10 µg/mL LPS exposure in the co-culture (P < 0.001). Application of butyrate also reduced IL-6 level in the co-culture after 10 µg/mL LPS treatment (P < 0.01). Lactobacillus plantarum 2142 decreased IL-8 level after incubation with 1 µg/mL LPS (P < 0.001), while in case of 10 µg/mL LPS treatment only a marginal lowering in IL-8 (P = 0.064) release was measured. The IL-6 concentration was significantly reduced (P < 0.01 in case of 1 µg/mL LPS treatment) by Lp2142 in the co-culture. Contrarily, the elevated IL-8 and IL-6 level of hepatocytes has not been reduced in case of either butyrate or Lp2142 addition. The enterohepatic co-culture model offers a possibility for fast and reliable screening of new candidates against enteric inflammation, which are of special interest in porcine medicine and health management. According to our results, Lp2142 and butyrate both seem to be effective as anti-inflammatory agents in LPS-triggered inflammatory response, tested in the gut-liver co-culture model.

Effects of dietary sodium butyrate on hepatic biotransformation and pharmacokinetics of erythromycin in chickens.

Butyrate, a commonly applied feed additive in poultry nutrition, can modify the expression of certain genes, including those encoding cytochrome P450 (CYP) enzymes. In comparative in vitro and in vivo experiments, the effect of butyrate on hepatic CYP genes was examined in primary cultures of chicken hepatocytes and in liver samples of chickens collected from animals that had been given butyrate as a feed additive. Moreover, the effect of butyrate on the biotransformation of erythromycin, a marker substance for the activity of enzymes of the CYP3A family, was investigated in vitro and in vivo. Butyrate increased the expression of the avian-specific CYP2H1 both in vitro and in vivo. In contrast, the avian CYP3A37 expression was decreased in hepatocytes following butyrate exposure, but not in the in vivo model. CYP1A was suppressed by butyrate in the in vitro experiments, and overexpressed in vivo in butyrate-fed animals. The concomitant incubation of hepatocytes with butyrate and erythromycin led to an increased CYP2H1 expression and a less pronounced inhibition of CYP3A37. In in vivo pharmacokinetic experiments, butyrate-fed animals given a single i.m. injection of erythromycin, a slower absorption phase (longer T(half-abs) and delayed T(max)) but a rapid elimination phase of this marker substrate was observed. Although these measurable differences were detected in the pharmacokinetics of erythromycin, it is unlikely that a concomitant application of sodium butyrate with erythromycin or other CYP substrates will cause clinically significant feed-drug interaction in chickens.

Genetic relatedness in wintering groups of house sparrows (Passer domesticus).

Social behaviour of group-living animals is often influenced by the relatedness of individuals, thus understanding the genetic structure of groups is important for the interpretation of costs and benefits of social interactions. In this study, we investigated genetic relatedness in feeding aggregations of free-living house sparrows (Passer domesticus) during the nonbreeding season. This species is a frequent model system for studies of social behaviour (e.g. aggression, social foraging), but we lack adequate information on the kin structure of sparrow flocks. During two winters, we ringed and observed sparrows at feeding stations, and used resightings to identify stable flock-members and to calculate association indices between birds. We genotyped the birds using seven highly polymorphic microsatellite loci, and estimated pairwise relatedness coefficients and relatedness categories (close kin vs. unrelated) by maximum likelihood method. We found that most birds were unrelated to each other in the flocks (mean +/- SE relatedness coefficient: 0.06 +/- 0.002), although most individuals had at least a few close relatives in their home flock (14.3 +/- 0.6% of flock-mates). Pairwise association between individuals was not significantly related to their genetic relatedness. Furthermore, there was no difference between within-flock vs. between-flock relatedness, and birds had similar proportions of close kin within and outside their home flock. Finally, relatedness among members of different flocks was unrelated to the distance between their flocks. Thus, sparrow flocks were not characterized by association of relatives, nevertheless the presence of some close kin may provide opportunity for kin-biased behaviours to evolve.

Bilateral striatal lesion associated with varicella.

Bilateral striatal lesion is characterised by a specific clinical syndrome (encephalopathy with rigidity, irritability, variable pyramidal, and extrapyramidal symptoms, speech abnormalities) and symmetrical lesion of the basal ganglia including the caudate nucleus, the putamen, and occasionally other nuclei. We report three cases in whom bilateral striatal lesion developed in association with varicella. Each patient recovered completely and showed no signs of cognitive deficiency, chorea or hyperkinetic syndrome, all of which have been reported as sequelae of BSL associated with other conditions. These cases suggest that bilateral striatal lesion may be an immune-mediated complication of varicella.

Photocycle of dried acid purple form of bacteriorhodopsin.

The photocycle of dried bacteriorhodopsin, pretreated in a 0.3 M HCl solution, was studied. Some properties of this dried sample resemble that of the acid purple suspension: the retinal conformation is mostly all-trans, 15-anti form, the spectrum of the sample is blue-shifted by 5 nm to 560 nm, and it has a truncated photocycle. After photoexcitation, a K-like red-shifted intermediate appears, which decays to the ground state through several intermediates with spectra between the K and the ground state. There are no other bacteriorhodopsin-like intermediates (L, M, N, O) present in the photocycle. The K to K' transition proceeds with an enthalpy decrease, whereas during all the following steps, the entropic energy of the system decreases. The electric response signal of the oriented sample has only negative components, which relaxes to zero. These suggest that the steps after intermediate K represent a relaxation process, during which the absorbed energy is dissipated and the protein returns to its original ground state. The initial charge separation on the retinal is followed by limited charge rearrangements in the protein, and later, all these relax. The decay times of the intermediates are strongly influenced by the humidity of the sample. Double-flash experiments proved that all the intermediates are directly driven back to the ground state. The study of the dried acid purple samples could help in understanding the fast primary processes of the protein function. It may also have importance in technical applications.

Characterization of the proton-transporting photocycle of pharaonis halorhodopsin.

The photocycle of pharaonis halorhodopsin was investigated in the presence of 100 mM NaN(3) and 1 M Na(2)SO(4). Recent observations established that the replacement of the chloride ion with azide transforms the photocycle from a chloride-transporting one into a proton-transporting one. Kinetic analysis proves that the photocycle is very similar to that of bacteriorhodopsin. After K and L, intermediate M appears, which is missing from the chloride-transporting photocycle. In this intermediate the retinal Schiff base deprotonates. The rise of M in halorhodopsin is in the microsecond range, but occurs later than in bacteriorhodopsin, and its decay is more accentuated multiphasic. Intermediate N cannot be detected, but a large amount of O accumulates. The multiphasic character of the last step of the photocycle could be explained by the existence of a HR' state, as in the chloride photocycle. Upon replacement of chloride ion with azide, the fast electric signal changes its sign from positive to negative, and becomes similar to that detected in bacteriorhodopsin. The photocycle is enthalpy-driven, as is the chloride photocycle of halorhodopsin. These observations suggest that, while the basic charge translocation steps become identical to those in bacteriorhodopsin, the storage and utilization of energy during the photocycle remains unchanged by exchanging chloride with azide.

Singular value decomposition with self-modeling applied to determine bacteriorhodopsin intermediate spectra: analysis of simulated data.

An a priori model-independent method for the determination of accurate spectra of photocycle intermediates is developed. The method, singular value decomposition with self-modeling (SVD-SM), is tested on simulated difference spectra designed to mimic the photocycle of the Asp-96 --> Asn mutant of bacteriorhodopsin. Stoichiometric constraints, valid until the onset of the recovery of bleached bacteriorhodopsin at the end of the photocycle, guide the self-modeling procedure. The difference spectra of the intermediates are determined in eigenvector space by confining the search for their coordinates to a stoichiometric plane. In the absence of random noise, SVD-SM recovers the intermediate spectra and their time evolution nearly exactly. The recovery of input spectra and kinetics is excellent although somewhat less exact when realistic random noise is included in the input spectra. The difference between recovered and input kinetics is now visually discernible, but the same reaction scheme with nearly identical rate constants to those assumed in the simulation fits the output kinetics well. SVD-SM relegates the selection of a photocycle model to the late stage of the analysis. It thus avoids derivation of erroneous model-specific spectra that result from global model-fitting approaches that assume a model at the outset.

Intermediate spectra and photocycle kinetics of the Asp96 --> asn mutant bacteriorhodopsin determined by singular value decomposition with self-modeling.

Singular value decomposition with self-modeling is applied to resolve the intermediate spectra and kinetics of the Asp96 --> Asn mutant bacteriorhodopsin. The search for the difference spectra of the intermediates is performed in eigenvector space on the stoichiometric plane. The analysis of data at pH values ranging from 4 to 8 and temperatures between 5 and 25 degrees C reveals significant, early partial recovery of the initial state after photoexcitation. The derived spectra are not biased by assumed photocycles. The intermediate spectra derived in the initial step differ from spectra determined in prior analyses, which results in intermediate concentrations with improved stoichiometric properties. Increasingly more accurate photocycles follow with increasing assumed complexity, of which parallel models are favored, consistent with recent, independent experimental evidence.

Interpretation of the spatial charge displacements in bacteriorhodopsin in terms of structural changes during the photocycle.

We have recently introduced a method, made possible by an improved orienting technique using a combination of electric and magnetic fields, that allows the three-dimensional detection of the intramolecular charge displacements during the photocycle of bacteriorhodopsin. This method generates electric asymmetry, a prerequisite for the detection of electric signal on the macroscopic sample, in all three spatial dimensions. Purple membrane fragments containing bacteriorhodopsin were oriented so that their permanent electric dipole moment vectors were perpendicular to the membrane plane and pointed in the same direction. The resulting cylindrical symmetry was broken by photoselection, i. e., by flash excitation with low intensity linearly polarized light. From the measured electric signals, the three-dimensional motion of the electric charge center in the bacteriorhodopsin molecules was calculated for the first 400 microseconds. Simultaneous absorption kinetic recording provided the time-dependent concentrations of the intermediates. Combining the two sets of data, we determined the discrete dipole moments of intermediates up to M. When compared with the results of current molecular dynamics calculations, the data provided a decisive experimental test for selecting the optimal theoretical model for the proton transport and should eventually lead to a full description of the mechanism of the bacteriorhodopsin proton pump.

Cellular basis of biventricular hypertrophy and arrhythmogenesis in dogs with chronic complete atrioventricular block and acquired torsade de pointes.

BACKGROUND: In the dog with chronic complete atrioventricular block (AVB), torsade de pointes arrhythmias (TdP) can be induced reproducibly by class III antiarrhythmic agents. In vivo studies reveal important electrophysiological alterations of the heart at 5 weeks of AVB, resulting in increased proarrhythmia. Autopsy studies indicate the presence of biventricular hypertrophy. In this study, the cellular basis of proarrhythmia and hypertrophy in chronic AVB was investigated. METHODS AND RESULTS: From chronic-AVB dogs with increased heart weights and TdP, left midmyocardial and right ventricular myocytes were isolated by enzymatic dispersion. These myocytes were significantly larger than sinus rhythm (SR) controls. In chronic AVB, the action potential spike-and-dome configuration was preserved. However, the action potential duration (APD) at 95% and 50% of repolarization of the left midmyocardium was significantly larger in chronic AVB than in SR, with little change in the right ventricle, causing enhanced interventricular dispersion of repolarization at slow pacing rates. Treatment with the class III agent almokalant increased the APD to a much larger extent in chronic-AVB than in SR myocytes and resulted in a higher incidence of early afterdepolarizations (EADs). EADs had their takeoff potential between -35 and 0 mV. There was no evidence that spontaneous sarcoplasmic reticulum Ca2+ release underlies these EADs. CONCLUSIONS: In the dog, chronic AVB leads to hypertrophy of both right and left ventricular myocytes. The repolarization abnormalities predisposing for class III-dependent TdP in vivo are the results of cellular electrophysiological remodeling.

Further observations to elucidate the role of interventricular dispersion of repolarization and early afterdepolarizations in the genesis of acquired torsade de pointes arrhythmias: a comparison between almokalant and d-sotalol using the dog as its own control.

OBJECTIVES: We sought to further elucidate the role of early afterdepolarizations (EADs) and interventricular dispersion of repolarization (deltaAPD) in the genesis of acquired torsade de pointes (TdP) arrhythmias. BACKGROUND: Administration of class III agents can be associated with TdP. We developed a dog model in which TdP can be reproducibly induced by pacing after d-sotalol. This model shows reproducible results over weeks. METHODS: In 14 anesthetized dogs with chronic complete atrioventricular block, two separate experiments were performed in which d-sotalol (2 mg/kg body weight) or almokalant (0.12 mg/kg) was administered. Monophasic action potentials were simultaneously recorded from the endocardium of the right and left ventricle to register EADs and to measure the action potential duration (APD). DeltaAPD was defined as the APD of the left ventricle minus that of the right ventricle. RESULTS: Baseline conditions were identical in the serially performed experiments. The cycle length and QT time increased by 16% and 26% after d-sotalol and by 15% and 31% after almokalant, respectively. After both drugs the action potential of the left ventricle prolonged more than that of the right ventricle, thereby increasing deltaAPD (almokalant [mean +/- SD]: 110 +/- 60 ms; d-sotalol: 80 +/- 45 ms, p < 0.05). The incidence of EADs (18 of 22 vs. 11 of 24, p < 0.05) and single ectopic beats (EBs) (1.5 +/- 2 vs. 24 +/- 32, p < 0.01) was more frequently observed after almokalant than after d-sotalol. Moreover, multiple EBs only occurred after almokalant. These beats interfered with the basic rhythm, leading to dynamic changes in left ventricular APD and to additional increases in deltaAPD. Spontaneous TdP was observed in 9 of 14 dogs after almokalant and could be increased to 12 of 14 with programmed electrical stimulation. After d-sotalol, TdP could only be induced by programmed electrical stimulation (5 of 14, p < 0.05). CONCLUSIONS: In the same dog, almokalant induced more delay in repolarization, more EADs, multiple EBs and more ventricular inhomogeneity in APD than d-sotalol. These changes were related to a higher incidence of TdP and thereby confirm a strong association of the occurrence of EADs, multiple EBs and deltaAPD in the genesis of TdP. These findings also show the possible value of our model for evaluating the proarrhythmic potential of different drugs.

Similarities between early and delayed afterdepolarizations induced by isoproterenol in canine ventricular myocytes.

OBJECTIVES: This study aims at clarifying the role of cellular Ca2+ overload and spontaneous sarcoplasmic reticulum (SR) Ca2+ release in the generation of early afterdepolarizations (EAD) by isoproterenol. The involvement of a Ca(2+)-activated membrane current in isoproterenol-induced EAD is investigated. METHODS: Membrane potential and contraction (an indicator of SR Ca2+ release) were recorded in canine left ventricular myocytes at pacing cycle lengths (CL) of 300-4000 ms. Threshold concentration for EAD was 20-50 mmol/l isoproterenol. Ni2+ (2.0-5.0 mmol/l) was used at normal and high (5.4 mmol/l) [Ca2+]o to examine the role of Ca2+ current and/or Na(+)-Ca2+ exchange (1Na-Ca) in EAD. RESULTS: In all cells delayed afterdepolarizations (DAD) appeared during isoproterenol. In most (approximately equal to 70%) cells EAD were also generated, which were fast-pacing dependent, occurring only at CL of 400-1000 ms. EAD were always initiated by a delay in repolarization. Early aftercontractions preceded the EAD upstrokes, often occurring without them. They coincided with the initial delays in repolarization. During treatment with isoproterenol, Ni2+ and high [Ca2+]o, EAD and DAD were suppressed despite the continued presence of early and delayed aftercontractions. CONCLUSIONS: Our data indicate that beta-adrenergic EAD share a common ionic mechanism with DAD in terms of cellular Ca2+ overload and spontaneous SR Ca2+ release. beta-Adrenergic EAD consist of two phases: (1) a conditional phase coinciding with the onset of an early aftercontraction, often followed by (2) an EAD upstroke. A Ca2(+)-activated membrane current, probably I Na-Ca, is necessary at least for the initiation of these EAD.

Studies on the effect of ursodesoxycholic acid on rats with acute carbontetrachloride injury.

Bilirubin is a sensitive marker of toxic liver injury. Carbontetrachloride (CCl4) is used in some manufactures and laboratories. An acute intoxication is a peril. We have performed experiments to state total, indirect and direct bilirubin levels in rats exposed to a single CCl4 dose of 1.25 ml/kg. Total bilirubin in normal rats is 3.13 +/- 0.13 mumol/l. 58.6% is direct conjugated and 41.3% indirect unconjugated bilirubin. One hour after CCl4 administration bilirubin started to increase and reached its peak in the second hour. 24 h later a decrease began but even 72 h after intoxication it was not normalized. Ursodesoxycholic acid (UDCA, CAS 128-13-2, Ursofalk) treatment (25 mg/kg/dose) lowered bilirubin, returning to normal level 24 h after CCl4 administration. Hypothermia aggravates intoxications. In CCl4 lesion it develops 1 h after exposure. UDCA has not influenced low body temperature but liver function, conjugating capacity was restored. In CCl4 poisoning it is suggested to start UDCA treatment as early as possible and to continue it for some more days after improvement of serum bilirubin concentration.

Systemic inflammatory response syndrome (SIRS) induced by carbon tetrachloride in rats.

We have observed the symptoms of systemic inflammatory response syndrome (SIRS) in male rats intoxicated by carbon tetrachloride (CCl(4)). Severe hypothermia, tachypnoea and increase in the heart beat min were diagnosed. These symptoms developed in the first hour of intoxication. The hepatic dysfunction was characterized by elevated bilirubin levels. In the sera we have measured increases in the activity of secretable (group II) phospholipase A(2) sPLA(2) (2,8x) and 6-ketoprostaglandin F(1alpha) (KPGF) (1,44x). Supposedly the free radicals derived from CCl(4)-mainly trichloromethyl-could induce the prompt reaction of SIRS and the release of sPLA(2) as well as the formation of KPGF. Our findings show that in the early phase of CCl(4) intoxication the symptoms of SIRS can be related to elevation of sPLA(2) and the products of cyclooxygenase II.

[Changes in fat metabolism in acute carbon tetrachloride intoxication of rats]. / Zsíranyagcsere változások patkányok heveny széntetraklorid mérgezésében.

CCl4 is an organic solvent and a well known hepatotoxic agent. Injury is mediated by reactive free radicals, mainly-CCl3 (trichloromethyl). Liver lesion develops within one-two hours, however, late toxic effects may appear after a delay of several hours or two to three days. Some drugs and liver toxicants cause disturbances in synthesis and metabolism of triglycerides, cholesterol and lipoproteins, thus damaging the basic resource for living cells. In our experiments a single 1.25 ml/kg CCl4 dose was administered s.c. to male Wistar rats. 24 hours later triglyceride level increased in the plasma by 223%. Cholesterol content suffered no changes. HDL-C level decreased by 40%. LDL-C concentration was higher by 235%. Cholesterol/HDL-C ratio increased by 0.75% on account of the practically unchanged cholesterol amount in the blood. The most often used calculation (Friedewald equation) LDL-C/HDL-C ratio was higher by 305%. The increased triglyceride content in the blood is in correlation with the fatty degeneration of the liver. The high LDL-C/HDL-C ratio may point to incipient atherosclerotic complications. The pathological lipid levels measured 24 hours after intoxication claim for delayed toxic effects to be taken into consideration. It may be suggested to determine the main lipid parameters after carbon tetrachloride exposition.

[Experimental myocardial infarct in rats induced by ligation of the coronary vessels. Electrophysiologic and ultrastructural study]. / Experimentálny infarkt myokardu u potkanov vyvolaný ligatúrami koronárnych ciev. Elektrofyziologická a ultrastrukturálna stúdia.

Ischemic damage of rat myocardium was produced by ligature of coronary arteries. Animals were studied in three groups: those dying of dysrhythmia, animals after ischemia lasting 10 minutes and 20 minutes. All of them were investigated by ECG and extrasystoles, bigeminia, trigeminia, salvos, ventricular tachycardia and fibrillation were found. Groups with ECG finding were sampled for electron microscopy. Ultrastructural findings documented ischemic damage of cardiomyocytes-clearing of basal sarcoplasm, clearing of perinuclear zones, occurring of cytolytic regions and even necrotic disintegration of cardiocytes.

Metabolic actions of a single atenolol and metoprolol dose.

Atenolol (CAS 29122-68-7) and metoprolol (CAS 37350-58-6) are beta 1-selective adrenoceptor antagonists without intrinsic sympathomimetic activity. beta-Receptor blockers influence carbohydrate- and lipid metabolism. Liver is a central organ of these processes. The metabolic fate of a single oral atenolol and metoprolol dose and their actions on carbohydrate- and lipid parameters have been investigated. Healthy male rats received a dose reducing heart beat/min by 25% (atenolol: 6 mg/kg; metoprolol: 10 mg/kg). About 9% of atenolol is metabolized by cytochrome P-450 (P-450). P-450-dependent functions (aminopyrine-N-demethylase, hexobarbital biotransformation time) were not inhibited. Serum bilirubin was normal. Triglyceride (TG), total cholesterol and HDL-cholesterol levels of the plasma were not affected. Transient blood glucose increase was measured returning to initial value at 120 min. Metoprolol is metabolized by hepatic monooxygenases. P-450-dependent functions were inhibited correlating to the lowered P-450-content of the microsomes. High TG level and decreased HDL-cholesterol content were measured. Blood glucose was significantly high. The liposoluble metroprolol affected the hepatic functions more than the hydrophilic atenolol. The monitoring of blood glucose during beta-receptor antagonist treatment may be suggested.