Response Of Pigs Research Articles

The Fusarium toxin deoxynivalenol (DON) modulates the LPS induced acute phase reaction in pigs

The systemic effects of the Fusarium toxin deoxynivalenol (DON) and of bacterial lipopolysaccharides (LPS) were studied in male castrated pigs (40.4±3.7kg) infused intravenously with either DON or LPS alone (100μgDON/kg/h, 7.5μg/LPS/kg/h), or together (100μgDON plus 7.5μg/LPS/kg/h). The Control group received a saline infusion (n=6/treatment, 24h observation period).An additional DON infusion did not exacerbate the clinical signs observed in LPS-infused pigs. For example, rectal temperature climaxed after 4h (40.4±0.2°C) and 5h (40.1±0.3°C), in the LPS and LPS+DON group, respectively. Saline and DON alone did not induce an acute phase reaction as indicated by unaltered plasma levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) while LPS caused a significant rise of both cytokines. TNF-alpha plasma peak concentrations were significantly higher in the LPS compared to the DON+LPS group (94.3±17.2ng/mL vs. 79.2±15.7ng/mL) while IL-6 climaxed earlier in the latter group (3h p.i. vs. 2h p.i.).From the tested clinical–chemical plasma characteristics the total bilirubin concentration and the ASAT activity were strongly elevated by the LPS infusion and additionally increased and decreased by DON, respectively.In conclusion, the LPS-induced effects were only marginally modified by DON.

3,4-Methylenedioxymethamphetamine induces a hyperthermic and hypermetabolic crisis in pigs with and without a genetic disposition for malignant hyperthermia

Clinical symptoms of acute 3,4-methylenedioxymethamphetamine (MDMA) intoxication and malignant hyperthermia have many similarities. At present, however, there is contradictory evidence concerning the malignant hyperthermia trigger potency of MDMA. This study was designed to investigate whether MDMA has malignant hyperthermia trigger potential and leads to malignant hyperthermia in pigs with or without a genetic predisposition to the condition. In addition, the therapeutic effectiveness of a new dantrolene sodium suspension was examined. Experimental study, using an animal model of Piétrain pigs. Institute for Research in Operative Medicine, University of Witten/Herdecke, Hospital Cologne Merheim, Cologne, Germany, October 2006 to February 2007. Trigger-free anaesthesia was performed on seven malignant hyperthermia-susceptible and six malignant hyperthermia-normal Piétrain pigs, and cumulative doses of MDMA were administered to each animal. After achieving predefined malignant hyperthermia criteria, standardised therapy was initiated; dantrolene sodium suspension (5 mg kg(-1)) was administered and the injection was repeated after 24 min. The malignant hyperthermia trigger potency of MDMA was analysed by monitoring pH, PaCO2 and temperature. In addition, concentrations of thyroid hormone, mitochondrial uncoupling protein 3, noradrenaline and free fatty acids during administration of MDMA and dantrolene sodium suspension were analysed. MDMA administration led to fulminant hypermetabolic and hyperthermic responses in malignant hyperthermia-susceptible and malignant hyperthermia-normal pigs, with significant decreases in pH (susceptible: pH 7.21 ± 0.11, normal: pH 7.21 ± 0.07), severe hypercapnia (susceptible: paCO2 10.3 ± 3.5 kPa, normal: paCO2 9.8 ± 1.7 kPa), and hyperthermia (susceptible: 40.6 ± 2.0°C, normal: 40.1 ± 0.4°C). There were no significant differences in changes in clinical and laboratory variables between groups. The dantrolene therapy regimen was effective in treating the MDMA-induced metabolic crises. MDMA is not a classic trigger for the development of malignant hyperthermia reactions in pigs. MDMA intoxication leads to severe, long-lasting hyperthermia and hypermetabolism in both malignant hyperthermia-susceptible and hyperthermia-normal pigs, with life-threatening malignant hyperthermia-like symptoms which are responsive to supportive treatment and dantrolene sodium suspension.

The plasma clearance of the Fusarium toxin deoxynivalenol (DON) is decreased in endotoxemic pigs

The plasma elimination kinetics of the Fusarium toxin deoxynivalenol (DON) was investigated in male castrated pigs (40.4±3.7kg) when infused intravenously either alone (100μg/kg/h, n=6) or together with lipopolysaccharides (LPS, 7.5μg/kg/h, n=6). The maximum DON concentration after one hour of infusion was significantly higher by 61% in the DON+LPS Group compared to pigs infused with DON alone. The area under the plasma DON concentration vs. time curve of the DON+LPS Group was approximately twice as high as that of the DON Group after 24h while the initial (0.63 vs. 0.6h) and terminal half-lifes (2.97 vs. 2.30h) remained uninfluenced. The apparent volume of distribution and the plasma clearance were significantly lower for the DON+LPS Group compared to the DON Group (2.14 vs. 1.45L/kg and 11.9 vs. 5.87mL/kg/min). Glucuronidated DON seemed to persist longer in the DON+LPS Group.In conclusion, clearance of DON was decreased during an LPS induced acute phase reaction in pigs. Whether the higher plasma DON concentrations in endotoxemic pigs are due to a hemodynamically associated longer persistence of the DON glucuronide or because of an altered glucuronidation activity needs to be examined further.

Cardiopulmonary hemodynamic responses to the small injection of hemoglobin vesicles (artificial oxygen carriers) in miniature pigs

Intravenous injection of liposomes into pigs reportedly induces anaphylactoid reactions at a small dose, resulting in circulatory disorder. Hemoglobin vesicles (HbVs) are artificial oxygen carriers encapsulating Hb solution in liposomes. It is not known how pigs respond to HbV injection. We aimed to analyze the cardiopulmonary responses to small injections of HbV and empty vesicle (EV) and compare them with a conventional liposome (CL) with a different lipid composition containing phosphatidylglycerol (PG). PG is known to induce an anaphylactoid reaction in pigs. Nine male miniature pigs were used for HbV, EV, and CL injections. The anesthetized pig received 0.05 and 0.5 mL/kg of a test fluid for the first and second injection with a 70 min interval. Results show that CL repeatedly induced significant increases in systemic and pulmonary arterial pressures and vascular resistances and decreases in heart rate and cardiac output (CO). HbV and EV at the first injection-induced pulmonary hypertension, with significantly smaller changes in systemic arterial pressure and CO. No remarkable response was visible at the second injection in spite of a larger dosage. Only CL repeatedly induced thrombocytopenia, leukocytopenia, and plasma thromboxane B(2) increase resulting from complement activation, although HbV and EV showed smaller changes. Transmittance electron micrograph of pulmonary intravascular macrophages (PIMs) showed phagocytosis of HbV, indicating the possibility that nonspecific phagocytosis by PIMs relates to the responses observed after the first injection. HbV does not induce a significant anaphylactoid reaction in pigs compared with CL because of the different lipid composition.

Liposome-induced complement activation and related cardiopulmonary distress in pigs: factors promoting reactogenicity of Doxil and AmBisome

Hypersensitivity reactions to liposomal drugs, often observed with Doxil and AmBisome, can arise from activation of the complement (C) system by phospholipid bilayers. To understand the mechanism of this adverse immune reaction called C activation-related pseudoallergy (CARPA), we analyzed the relationship among liposome features, C activation in human serum in vitro, and liposome-induced cardiovascular distress in pigs, a model for human CARPA. Among the structural variables (surface charge, presence of saturated, unsaturated, and PEGylated phospholipids, and cisplatin vs. doxorubicin inside liposomes), high negative surface charge and the presence of doxorubicin were significant contributors to reactogenicity both in vitro and in vivo. Morphological analysis suggested that the effect of doxorubicin might be indirect, via distorting the sphericity of liposomes and, if leaked, causing aggregation. The parallelism among C activation, cardiopulmonary reactions in pigs, and high rate of hypersensitivity reactions to Doxil and AmBisome in humans strengthens the utility of the applied tests in predicting the risk of CARPA. From the Clinical Editor The authors studied complement activation-related pseudoallergy (CARPA) in a porcine model and demonstrate that high negative surface charge and drug effects leading to distortion of liposome sphericity might be the most critical factors leading to CARPA. The applied tests might be used to predict CARPA in humans.

245 ANALYSIS OF CORTICAL GRANULE EXUDATE OBTAINED BY CHEMICAL OOCYTE ACTIVATION IN PIGS

Cortical granules (CG) are clue organelles in the mammalian oocyte because once released, their content modifies the zona pellucida (ZP) and oolema, thus preventing polyspermy. However, research on putative CG proteins has progressed slowly because of the picogram amount of proteins contained in CG. Isolation and identification of CG contents in porcine oocytes would help to elucidate the molecular mechanism involved in blocking polyspermic fertilization. Our objective was to study the contents of CG from in vitro-matured (IVM) porcine oocytes, and to achieve this objective, CG exudate was collected after its release from chemically activated oocytes. Oocytes were subjected to IVM in porcine oocyte medium supplemented with 50 μM β-mercaptoethanol for 44 h. After the IVM period, the ZP was removed by protease treatment (0.5% pronase in PBS), and the ZP-free oocytes were activated with calcium ionophore A23187 (6.5 μM, 2 min) in a medium consisting of 114.06 mM NaCl, 3.20 mM KCl, 0.50 mM MgCl2·6H2O, 10.00 mM sodium lactate, 0.35 mM NaH2PO4, 5.00 mM glucose, 25.07 mM NaHCO3, and 8.00 mM calcium lactate·5H2O. After activation, oocytes were transferred to fresh medium without calcium ionophore and kept for 30 min to allow release of the CG content. After this time, medium containing the CG exudate was collected, as well as the activated oocytes, and both samples were stored at –80°C until analysis. Samples were thawed and the CG proteins were concentrated by centrifugation in 10-kDa centrifugal devices (Microcon, Millipore, Billerica, MA) following the manufacturer’s instructions. The CG exudates from activated oocytes (n = 300) and activated oocytes (n = 125) were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions. In brief, 4% stacking and 12% separating gel was used and run using 25 mM Tris–0.2 M glycine buffer, pH 8.6, containing 0.1% SDS for 1.5 h at 150 V and room temperature. After electrophoresis, the gel was silver stained. Thirteen strong bands were identified in the CG exudate lane, with an approximate molecular mass from approximately 45 to 105 kDa. However, the lane for activated oocytes showed faint protein bands. The presence of well-defined bands in the CG exudate lane might correspond to different CG-derived proteins. These preliminary results show a new approach for studying CG content. Further proteomic analysis of the bands will help to describe specific proteins contained in these organelles, shedding light on the role of the cortical reaction in pigs. Supported by MEC and FEDER (AGL2009-12512-C02-01) and Okayama Universit R. R. was granted funding by JSPS (Ref. S-09210).

PREFERENCE BEHAVIOUR OF PIGS AS AN ASSESSMENT CRITERION FOR HOUSING SYSTEMS

This experiment is part of a research project which analyzes the reaction of pigs to different housing systems or to segments of animal husbandry systems. The aim of this project is to identify the preference behaviour of pigs using sensor-based technology, i.e. to identify the preference towards differently designed housing methods. The chosen approach assumes that the preference for different kinds of areas can be illustrated as a function of time (duration of stay, period of stay). A sensor-based animal identification-system was employed to continuously define the habitation and the duration of stay. In the first part of the experiment, housing on straw litter with free airing was compared to housing on totally slatted floor with full air conditioning. The results showed a clear preference for the straw litter system. In the experiment described below, housing on a totally slatted floor was compared to housing on a partly slatted floor. A clear preference for one system could not be noticed over the whole fattening period

Pig's responses to repeated social regrouping and relocation during the growing-finishing period

In animal husbandry, pigs have to cope with social challenges when regrouped with unfamiliar conspecifics. Regrouping pigs may result in an acute stress and physical injuries thus reducing animal welfare. The aim of the present experiment was to evaluate the behavioural, cortisol and growth responses of pigs to a repeated social stress. Thirty-two growing-finishing pigs were housed in pairs. Animals of half of the pairs were placed in a new pen with a new partner three times a week during 4 weeks (R pigs, n = 8 pairs). Other animals stayed in the same pen with the same partner (C pigs, n = 8 pairs). During the first 90 min following each regrouping, vigorous fights were frequent in R pigs. Those pigs exhibited more agonistic behaviour than C pigs throughout the experiment ( P < 0.05). The number of offensive acts realized by R pigs decreased throughout the experiment ( P < 0.05) whereas the number of defensive acts did not vary ( P > 0.1). The time-budget determined during 24 h 2 days after the third, sixth, ninth and 12th regrouping was similar in R and C pigs except the percentage of standing that was higher in R pigs after the last regrouping. R pigs tended to have a lower daily liveweight gain at the fifth regrouping ( P = 0.07). Salivary cortisol concentrations were higher in R than in C pigs 4–5 h after the second and fifth regrouping ( P < 0.05) but were similar in both groups after the ninth and 11th regrouping. Basal cortisol measured 2 days after the last regrouping in plasma and saliva was higher in R than C pigs. In response to a dexamethasone/ACTH challenge, cortisol in saliva and plasma was similar in both groups ( P > 0.05). The behavioural and cortisol responses to regrouping and relocation in pigs decreased over time but were still obvious after 12 mixings. Repeated regroupings induce a chronic stress in pigs without altering severely growth rate.

Effects of dexamethasone application in growing pigs on hormones, N-retention and other metabolic parameters.

Many single effects of glucocorticoids are known but complex metabolic reactions in pigs in response to a glucocorticoid challenge were not reported. Seven pigs (mean weight 69 kg) with indwelling catheters were kept in metabolic crates. After a 7-day control period they were fed for 9 days with 0.4 mg dexamethasone (dex) per kg body weight daily, followed by another 9-day post-treatment period. Hormones and metabolic parameters were continuously determined in urine or blood plasma. Treatment significantly changed all parameters except non-esterified fatty acids. Cortisol decreased from 84.5 to 4.9 nmol/l, insulin-like growth factor I (IGF-I) from 17.5 to 10.8 nmol/l and aldosterone from 0.36 to 0.13 nmol/l. The N-retention decreased from 1.07 to 0.53 g/kg(0.75) and hydroxyproline from 2.97 to 1.05 mmol/day. An increase was found for urine volume (5.2 versus 13.6 l/day), urea-N (0.90 versus 1.43 g/kg(0.75)), allantoin (6.40 versus 8.75 mmol/day), glucose (3.9 versus 4.34 mmol/l) and insulin (6.21 versus 11.16 mU/l). In the post-treatment period IGF-I revealed a compensatory pattern (control period versus post-treatment period: 17.5 versus 22.9 nmol/l) whereas the other parameters were not significantly elevated. Data suggest that dex increased N-excretion both by inhibiting mitosis and resynthesis of proteins partly via a reduced collagen synthesis. Increased allantoin concentrations additionally pointed to increased apoptosis.

Nitric oxide synthase inhibition augments acute allergic reactions in the pig airways in vivo.

The aim of this study was to examine the effects of nitric oxide synthase inhibition on antigen- and histamine-induced acute airway reactions, in order to clarify the possible modulating role of NO. Twelve specific-pathogen-free pigs (sensitized with Ascaris suum antigen) were challenged with an antigen aerosol during mechanical ventilation and anaesthesia. Six pigs were pretreated with N(G)-nitro-L-arginine (L-NA, 10 mg x kg(-1)), a NO synthase inhibitor, 30 min before challenge. In separate experiments, seven sensitized pigs received histamine (5 mg) aerosols before and after L-NA treatment. It was found that pretreatment with L-NA resulted in an enhanced airways resistance response to antigen (areas under the curve 0-90 min were (mean+/-SEM) 1,119+/-160 versus 555+/-56 (cmH2O x L(-1) x s(-1) x min for controls, p<0.05 (Mann-Whitney U-test), whereas this response to histamine was not affected by L-NA. Moreover, L-NA pretreatment significantly enhanced total protein (1.85+/-0.43 versus 0.31+/-0.06 g x L(-1), p<0.01) and histamine levels (42.8+/-16.0 versus 2.6+/-0.8 nM, p<0.05) in bronchoalveolar lavage fluid 45 min after antigen challenge. In conclusion, this study showed that N(G)-nitro-L-arginine enhanced reactions occurring during the acute allergic reaction in pigs in vivo. This indicates a protective role of nitric oxide, which might occur through downregulation of histamine release from mast cells rather than a direct bronchodilating effect of nitric oxide.

Porcine CD5 gene and gene product identified on the basis of inter-species conserved cytoplasmic domain sequences

Analysis of published CD5 amino acid sequences identified conserved sequences with potentially immunogenic epitopes. To obtain anti-porcine CD5, synthetic peptides representing conserved sequences identified in mouse, human, cattle and sheep CD5 cytoplasmic tail domains were linked to KLH and used to immunize rabbits. Anti-synthetic peptide serum reacted with an antigen extracted from porcine lymphocyte membrane which was consistent in size (67 kDa) with CD5. Murine monoclonal anti-porcine wCD5 (b53b7) and the anti-CD5 synthetic peptide serum react with the same ligand confirming that porcine wCD5 has conserved amino acid sequences similar to those of CD5 of several species. Analysis of porcine genome for CD5 gene sequences by PCR was conducted to verify the presence of CD5-like genes. Oligomeric primers were designed to identify CD5-like sequences by polymerase chain reaction in pigs and other species. Amplified DNA similar in size to that predicted for CD5 elements were amplified from a variety of animal genomes including that of pig. The porcine-derived fragment was cloned and shown to be 96% similar to mouse CD5. The use of published CD sequences for prediction of immunogenic peptides has provided a complimentary alternative to the more traditional approaches to production of CD-specific antibodies.

The role of E-selectin in lymphocyte and polymorphonuclear cell recruitment into cutaneous delayed hypersensitivity reactions in sensitized pigs.

We have studied the role of E-selectin in leukocyte accumulation into Ag-specific cutaneous delayed-type hypersensitivity reactions in pigs sensitized to the topical application of 2,4-dinitro-1-fluorobenzene or to the intradermal injection of bacillus Calmette-Guérin. The delayed-type hypersensitivity reactions were shown to be specific for the sensitizing Ag and characterized by the up-regulation of E-selectin, as demonstrated by the uptake of tracer 99mTc-labeled monoclonal anti-E-selectin mAb and entry of 51Cr-labeled PBL and (111)In-labeled polymorphonuclear cells (PMN). Intravenous injection of 5 mg/kg of a F(ab')2 preparation of a monoclonal anti-E-selectin Ab at peak times of leukocyte entry resulted in a significant inhibition of entry of both PMN and lymphocytes. The anti-E-selectin Ab inhibited PMN recruitment by 70 to 90% and lymphocyte recruitment by 50 to 60%. In comparison, an anti-CD18 treatment reduced PMN recruitment by 70 to 90% and lymphocyte recruitment by 60 to 70% in this model. These data confirm an important role for E-selectin in the recruitment of both PMN and lymphocytes to sites of immune-based dermal inflammation.

The use of compositional growth curves for assessing the response to dietary lysine by high-lean growth gilts

AbstractGrowth modelling was used to characterize the response to digestible lysine in two experiments (114 gilts in experiment 1 and 96 gilts in experiment 2) from 34 to 72·5 kg and 72·5 to 136 kg, respectively. Maize-soya-bean meal diets were formulated to assure that lysine (5·4 to 10·4 and 5·4 to 9·4 g digestible lysine per kg for experiments 1 and 2, respectively) was the first limiting amino acid. Analysis of variance was used to test linear and quadratic responses in cumulative weight gain on test as digestible lysine increased. A time × digestible lysine interaction (linear, P &lt; 0·001) was detected, indicating that a separate regression equation for each lysine level was necessary. In experiment 1, average daily gain (ADG) and carcass crude protein (CP) accretion were maximized for gilts given 10·4, 9·4 and 8·4 g digestible lysine per kg from 34 to 44 kg, 44 to 54 kg, and 54 to 72·5 kg, respectively. Lipid accretion was minimized for gilts given 7·4 to 8·4 g digestible lysine per kg. In experiment 2, ADG was maximized by feeding 8·4 g/kg from 72·5 to 92·5 kg and 7·4 g/kg from 92·5 to 136 kg. Carcass CP accretion was maximized by feeding 9·4 g digestible lysine per kg, whereas lipid accretion was minimized for gilts given 8·4 g digestible lysine per kg from 72·5 to 136 kg. If feeding graded levels of digestible lysine resulted in parallel lines for protein accretion, mean values would result in accurate data evaluation. However, responses to digestible lysine changed over the feeding period. Therefore, the use of body weight and compositional growth curves offers an approach to more accurately characterize the growing pig's response to increased digestible lysine.

The phytohaemagglutinin (PHA) skin test as an indicator of stress-induced changes in immune reactivity in pigs.

The present study describes two experiments to standardize the phytohaemagglutinin (PHA) skin test as an indicator of lymphocyte reactivity in pigs after exposure to stressful situations in practical pig husbandry. The first experiment was a dose-response experiment. No time dose interaction was found, so the pattern of the reaction was the same for all doses used, although the magnitude of the reaction differed. The second experiment was carried out to determine stress-induced changes in lymphocyte reactivity. One half of a group of 48 pigs was exposed to stress (mixing, moving, and an increased stocking density). The immune reactivity to intradermally injected PHA of stressed animals differed significantly (P < 0.01) from that of unstressed controls. The reaction of stressed animals can be characterized by a delayed reaction with a lower peak. It can be concluded that frequent measurements are preferable to single measurements when the effects of stress on immunological processes are studied.

Substance P level is increased in the cholesterol induced anaphylactoid reaction in the pig.

The role of substance P (SP) in cholesterol-induced anaphylactoid reaction was investigated in 13 Landrace pigs. Pigs were anesthetized with sodium thiopental and ventilation was controlled with 70% nitrous oxide in oxygen. A Swan-Ganz catheter and a carotid arterial line were placed to monitor the hemodynamic data. Group 1 pigs (control group, n = 5) each received 20 ml of intravenous (IV) colloid infusion solution (Haemaccel) and group 2 pigs (cholesterol group, n = 8) each received an IV injection of pure cholesterol emulsion (12 mg/kg) in 20 ml of Haemaccel. Blood samples for SP and histamine (H) levels were taken just before and for 10 min following the placebo, Haemaccel, and cholesterol injections. Urine samples were also collected just before and at 60 min following the injections for methyl histamine (MH) levels. Group 2 pigs (cholesterol) developed an anaphylactoid reaction as indicated by marked and significant hemodynamic changes. None of the group 1 (placebo) pigs developed an anaphylactoid reaction. Significant increases in blood SP and H levels (P < 0.05), and urine MH levels (P < 0.05) were seen in cholesterol-treated pigs (group 2), whereas no significant changes were seen in control pigs (group 1). Our results suggest that SP is involved in the cholesterol-induced anaphylactoid reaction in pigs.

Independent segregation of a hyperactive hypothalamic-hypophyso-adrenal axis and a reduced behavioural reactivity in pigs

When compared to European Large White, Chinese Meishan pigs have high levels of circulating ACTH and cortisol, and a reduced behavioral reactivity in various challenging situations such as esposure to a novel environment, two characteristic features of depression. We investigated whether this association is genetically built in or whether these psychobiological characteristics are fortuitously associated. Six-week-old piglets from the segregating F2 crosses between the Meishan and Large White breeds were studied in a standardised protocol of novel environment exposure. As expected from the genetic diversity, a wide range of variation was recorded for behavioural reactivity immediately before the test and at the end of the session. Again these measures varied considerably between animals, and the continous distribution of the scores suggested the they are under control of numerous genes. Furthermore, no correlation could be found between neuroendocrine and behavioural measures. This result demonstrate that the association between high ACTH/corticosteroid levels and a low behavioral reactivity is not genetically controlled.

Local pathological reactions induced in pigs and cats by adjuvant ISA-70 containing inactivated Newcastle disease virus antigen.

Gross and microscopic changes at the injection site in pigs and cats were investigated for 8 weeks after an intramuscular injection of oil adjuvant ISA-70 emulsion, containing inactivated Newcastle disease virus antigen. In pigs, an egg-sized and discolored lesion with pinpoint to miliary-sized nodules was observed at 2 to 8 weeks post injection (PI). In cats, there was partial thickening of the subcutaneous tissue at 2 to 8 weeks PI. Histopathologic changes in pigs were fundamentally similar to those in cats, however, the local tissue reactions in pigs were severer and more protracted than those in cats. The lesions in pigs were characterized by formation of large-sized cysts and well-developed encapsulation of the cysts with epithelioid cells.

Heparin-protamine reactions in pigs: role of oxygen-derived free radicals

We tested the hypothesis that pulmonary hypertension and thromboxane A2 release after heparin neutralization by protamine are mediated by oxygen free radicals. Forty-five pigs in five groups were studied during general anesthesia. Group I animals received 250 IU heparin followed by 100 mg protamine after 15 min. Group II and group III animals received dimethyl sulfoxide (DMSO) and dimethylthiourea (DMTU) 30 min before heparin infusion. Group IV animals were given superoxide dismutase (SOD) 5 min before protamine. Group V served for testing the pulmonary vascular reactivity in DMTU-treated animals to a thromboxane A2 analogue (U-46619). Generation of oxygen free radicals by polymorphonuclear granulocytes (PMNs) was measured in vitro by chemiluminescence. Severe pulmonary hypertension and thromboxane A2 release after protamine were not prevented by either DMSO or SOD. DMTU reduced pulmonary vasoconstriction to U-46619 and protamine but not to TxA2 release, indicating that DMTU had unspecific vascular effects in group III. Heparin-protamine released no oxygen free radicals from isolated PMNs. The results indicate that oxygen free radicals do not have a key role in mediating pulmonary vasoconstriction after protamine neutralization of heparin.

Effects of drugs combining H1 and H2 receptor antagonist activity on histamine release and life threatening anaphylactoid reactions in pigs

Two recently synthetized drugs combining H1- and H2-receptor antagonist activity in a single molecule (alitidine, clophetidine) were compaired for their potency in preventing histamine release and lifethreatening anaphylactoid reactionin vivo with the usually tested H1/H2-blocker combination dimetindene/cimetidine. Saline premedication in a fourth group served as control. Anaesthetized and ventilated pigs were administered H1/H2-blockers or placebo and 500 ml of blood were removed. Subsequently, 500 ml saline solution containing 1 mg/kg compound 48/80 for initiating histamine release were rapidly reinfused (n=15 pigs per group). The system proved reliable in creating hypotension and histamine release in the placebo group. The extent of histamine release did not differ between the placebo, alitidine and dimetindene/cimetidine groups. However, clophetidine was shown to be effective in preventing increases in plasma histamine after compound 48/80. Tachycardia was almost completely prevented by dimetindene/cimetidine, was diminished by clophetidine, but was not affected by alitidine. Hypotension following 48/80 was best reversed by clophetidine. This investigation suggests that clophetidine is a most promising drug in preventing histamine release and its circulatory effects in a pig anaphylactoid shock model. It requires, however, further quantitative confirmation in experiments with a two-group design only, since the analysis of variance is less suitable for the extreme variation of the plasma-histamine values after administration of compound 48/80.

Cerebral haemodynamic and electrocortical CO2 reactivity in pigs anaesthetized with fentanyl, nitrous oxide and pancuronium.

Cerebral haemodynamic, metabolic and electrocortical reactivity to alterations in arterial CO2 tension (PaCO2) was assessed in seven mechanically ventilated juvenile pigs to test an experimental model designed for cerebral pharmacodynamic and pharmacokinetic studies. The animals were anaesthetized with fentanyl, nitrous oxide and pancuronium and sequentially normo- and hyperventilated over a 100-min period. Five measurements were made at 25-min intervals. The cerebral blood flow (CBF) was measured with the intra-arterial 133Xe technique and the cerebral metabolic rate for oxygen (CMRO2) determined from CBF and the cerebral arteriovenous oxygen content difference. A linear correlation (r = 0.845) was found between CBF and PaCO2. The cerebrovascular reactivity to hypocapnia (delta CBF/delta PaCO2) was maintained throughout the experimental period and amounted to (95% confidence interval) 9.1 (7.1-11.1) ml x 100 g-1 x min-1 x kPa-1 within the PaCO2 range 3.3-6.3 kPa. The CMRO2 was not influenced by hyperventilation. The baseline electroencephalographic (EEG) pattern was stable at normocapnia (mean PaCO2 5.6 kPa), whereas spectral values for delta and total average voltage increased significantly (P < 0.05) at extensive hypocapnia (3.5 kPa). Maintenance of cerebral CO2 reactivity and spectral EEG voltage at a stable plasma level of fentanyl is complementary to the cerebral haemodynamic and metabolic stability previously found at sustained normocapnia in this model.