Assessing the effect of breed, age, and sex on muscarinic receptor distribution in atria and ventricles of turkeys.

Atrial and ventricular myocardium from young (6-wk-old), young adult (3-6-mo-old), and aged (14-15-mo-old) meat-type (B.U.T. Big 6) and wild-type (Cröllwitzer) turkeys were used to study the influence of age and sex on cholinergic muscarinic receptors using [3H]-N-methyl-scopolamine (3H-NMS) binding studies. In both breeds, saturation experiments indicated the presence of regional-, sex-, and age-related differences in the density of cholinergic muscarinic receptors (Bmax), that is, a decrease or increase. Except for right atria, Bmax was decreased in both male and female B.U.T. Big 6 hearts with increasing age. Similarly, a negative correlation between Bmax and age could be seen in female and male atria of Cröllwitzer turkeys, while positive correlation could be seen in right and left ventricles of male, and only right ventricles of female Cröllwitzer turkeys. The affinity of the receptor (KD) was not affected by age, sex and breed. In all cardiac chamber tissues, the M2-subtype was shown to be predominant followed by the M3-subtype and to a lesser extent the M1-subtype. Aspects of this age-dependent remodeling of the heart differ between sexes, resulting in maladaptive changes in older turkeys with a high degree of frailty. These observations may help explain why males and females are susceptible to different cardiovascular diseases as they age and why frail older adults are most often affected by these diseases.

Dimethyl sulfoxide favors the emetic efficacy of lycorine in beagle dogs - a novel strategy for the treatment of poisoning.

Poisoning in small animals represents an ongoing hazard and therapeutic problem in veterinary medicine. Therapeutic induction of emesis in time enables a fast elimination of a toxic compound resulting in a shortened course of poisoning and a higher safety level thereafter, which decisively improves prognosis and treatment. Lycorine is a reliable emetic drug in beagle dogs without serious side effects thought to be more beneficial in tolerability and efficacy than the rarely used apomorphine. Therefore, this study investigates efficacy and tolerability of differently composed potential drug formulations of lycorine hydrochloride for s.c. administration in dogs as an emetic principle. By emesis response analysis four dimethyl sulfoxide (DMSO)-based active pharmaceutical ingredient (API) formulations were favored. Two of them (F5 and F6) qualified for further drug development. Both formulations ensure a safe pharmacologically induced emesis within about 30 min after injection, suitable for use as an in time decontaminant in acute poisoning of dogs. DMSO-based formulations were well tolerated and offer a novel promising strategy for treatment of poisoning.

The Rho kinase (ROCK) inhibitor Y-27632 reduces the ß2-adrenoceptor density but enhance cAMP formation in primary equine bronchial epithelial cells.

The present study addresses the effect of the Rho-kinase (ROCK) inhibitor Y-27632 on the ß2-adrenoceptor density and ß-agonist-stimulated intracellular second messenger cAMP formation in primary equine bronchial epithelial cells (EBEC). Y-27632 significantly decreased the ß2-adrenoceptor number (Bmax) without markedly affecting the receptor affinity (dissociation constant, KD) to the radioligand [125I]-iodocyanopindolol (ICYP). In contrast, Y-27632 augmented the ß-agonist-stimulated intracellular cAMP production. Herein, Y-27632 markedly increased the maximal cAMP responses (Emax) (isoproterenol > epinephrine > norepinephrine) but did not shift the ß-agonist concentration-effect curves to the left. The ß2-selective antagonist ICI 118.551 and the ß1/ß2-antagonsit propranolol but not the ß1-selctive antagonist CGP 20712A reversed the isoproterenol-induced cAMP formation equally in Y-27632-treated and control EBEC, suggesting the effect was merely related to the ß2-subtype. These results show that Y-27632 differentially regulates the receptor density and function. Thus, these findings provide the first evidence that the functional interaction of the ß2-adrenoceptor and Rho-kinase (ROCK) signaling pathways decreases the receptor expression but enhances receptor downstream cAMP formation. This differential regulation of the receptor density and function by Y-27632 should be further reconsidered with regard to the beneficial effect of the drug in asthma therapy.

Expression of muscarinic acetylcholine receptors in turkey cardiac chambers.

The aim of the present study was to characterize the specific binding sites for [N-methyl-3H]-scopolamine ([3H]-NMS), a radioligand for labeling muscarinic acetylcholine receptors (mAChRs), in membranes of four heart chambers obtained from adult male British United Turkey (BUT) Big 6 ("meat-type") and Cröllwitzer ("wild-type") turkeys. MAChR subtypes were examined by inhibiting [3H]-NMS binding with subtype selective non-labelled receptor antagonists. In all left and right atria as well as left and right ventricles of both turkey breeds, the specific [3H]-NMS binding was saturable, reversible and of high affinity (KD range: 0.5-1.0 nM). The maximum receptor density (Bmax) was not significantly different between the four cardiac chambers of BUT Big 6 turkeys, but a significant difference was found between atria and ventricles of Cröllwitzer turkeys. Moreover, significant lower Bmax was found in the atria of Cröllwitzer turkeys than in the atria of BUT Big 6, while the ventricular Bmax was significantly higher. In all cardiac chambers, unlabeled mAChR antagonists competed for specific [3H]-NMS binding sites in a concentration-dependent manner, suggesting the presence of the M3 and M2 receptor subtypes, whereby the latter was the predominant subtype. The presence of the M1 subtype could not be excluded. In conclusion, there was a difference between BUT Big 6 ("meat-type") and Cröllwitzer ("wild-type") turkeys with regard to receptor density in heart chambers with dominant M2 and M3 receptor subtypes.

Effects of Hypoxia and Acidosis on Cardiac Electrophysiology and Hemodynamics. Is NHE-Inhibition by Cariporide Still Advantageous?

Hypoxia often leads to severe cardiac malfunctions. It is assumed that intracellular calcium overload is -inter alia- responsible for left ventricular (LV) deterioration. Inhibition of the sodium-proton exchanger (NHE), which finally inhibits/slows calcium overload, may ameliorate cardiac function. Our aim was to evaluate cariporide, an inhibitor of NHE1 in a Langendorff-perfused heart model. To discriminate a potentially different impact of extracellular acidosis and hypoxia we examined 48 Chinchilla Bastard rabbits divided into 8 experimental groups: control group (pH = 7.4, O2 = 100%) without or with cariporide (1 µM), acidosis group (pH = 7.0, O2 = 100%) without or with cariporide (1 µM), hypoxia group (pH = 7.4, O2 = 40%) without or with cariporide (1 µM) and hypoxia+acidosis group (pH = 7.0, O2 = 40%) without or with cariporide (1 µM). Hearts were subjected to acidotic/hypoxic conditions for 90 min followed by 60 min of reperfusion. Hypoxia and hypoxia+acidosis led to a severe deterioration of LV function with a decrease in LV pressure by about 70% and an increase of end-diastolic pressure from 6.7 ± 0.6 to 36.8 ± 5.4 (hypoxia) or from 7.0 ± 0.2 to 18.6 ± 4.1 (hypoxia+acidosis). Moreover, maximum contraction velocity decreased from about 1,800 mmHg/s to 600 mmHg/s during hypoxia ± acidosis and maximum relaxation velocity deteriorated from -1,500 mmHg/s to about -600 mmHg/s. During reperfusion hearts subjected to hypoxia+acidosis recovered faster than hearts subjected to hypoxia alone, reaching control levels after 5 min of reperfusion. Electrophysiologic analysis revealed an 1.2 fold increase in both dispersion of activation-recovery interval and in total activation time in the hypoxia ± acidosis group. Cariporide application significantly improved LV hemodynamics and electrophysiology in the hypoxia group but not in the group subjected to hypoxia+acidosis. Immunohistologic analysis of cardiac specimen revealed a significant increase of factors involved in hypoxia/reperfusion injury like nitrotyrosine and poly-ADP-ribose as well as apoptosis-inducing factors like AIF or cleaved-caspase 3 in LV after hypoxia ± acidosis. ATP was reduced by hypoxia but not by acidosis. Again, cariporide mitigated these processes only in the hypoxia alone group, but not in the group with additional acidosis. Acidosis without hypoxia only marginally disturbed LV function and electrophysiology, and was not affected by cariporide. Thus, our study demonstrated that several detrimental effects of hypoxia were mitigated or abrogated by acidosis and that NHE-inhibition improved only hypoxia-induced cardiac dysfunction.

Presence and function of ß-adrenergic receptors in primary equine bronchial epithelia cells.

The ß-adrenergic receptor (ß-AR) plays an important role in regulating a variety of cell and organ functions in different animal species and is an important target in asthma pathogenesis and therapy. The ß-AR expression and function in equine bronchial epithelial cells (EBEC) were not known but innervation and significant decrease in receptor level were reported in the equine bronchial tissues from asthmatic horses. 125I-iodocyanopindolol (ICYP) binding studies were undertaken in primary freshly isolated and cultured EBEC to identify the presence of the ß-ARs. The receptor distribution was assessed using subtype-selective ß-AR antagonists (ICI 118 551 (ß2) and CGP 20712A (ß1). The ß-AR function was confirmed by measuring the agonist-induced intracellular cAMP accumulation in freshly isolated and cultured EBEC. In both freshly isolated and cultured EBEC, the specific ICYP binding was saturable and of high affinity. The maximal receptor density (Bmax) was 9763 ± 140 binding sites/cell (mean ± SEM, n = 7) and 10575 ± 194 binding sites/cell (mean ± SEM, n = 5) in freshly isolated and cultured EBEC, respectively. The receptor affinity to the ligand (KD) was also not different between the two cell conditions. ICI 118.551 displaced ICYP with 25 000-fold higher affinity than CGP 20712A. Moreover, in both fresh isolated and cultured EBEC, cAMP-accumulation was stimulated with a rank-order of potency of isoproterenol > adrenaline > noradrenaline. These results highlight the ß2-AR to be a key subtype in both freshly isolated and cultured primary EBEC.

Equine bronchial fibroblasts enhance proliferation and differentiation of primary equine bronchial epithelial cells co-cultured under air-liquid interface.

Interaction between epithelial cells and fibroblasts play a key role in wound repair and remodelling in the asthmatic airway epithelium. We present the establishment of a co-culture model using primary equine bronchial epithelial cells (EBECs) and equine bronchial fibroblasts (EBFs). EBFs at passage between 4 and 8 were seeded on the bottom of 24-well plates and treated with mitomycin C at 80% confluency. Then, freshly isolated (P0) or passaged (P1) EBECs were seeded on the upper surface of membrane inserts that had been placed inside the EBF-containing well plates and grown first under liquid-liquid interface (LLI) then under air-liquid interface (ALI) conditions to induce epithelial differentiation. Morphological, structural and functional markers were monitored in co-cultured P0 and P1 EBEC monolayers by phase-contrast microscopy, scanning and transmission electron microscopy, hematoxylin-eosin, immunocytochemistry as well as by measuring the transepithelial electrical resistance (TEER) and transepithelial transport of selected drugs. After about 15-20 days of co-culture at ALI, P0 and P1 EBEC monolayers showed pseudo-stratified architecture, presence of ciliated cells, typically honeycomb-like pattern of tight junction protein 1 (TJP1) expression, and intact selective barrier functions. Interestingly, some notable differences were observed in the behaviour of co-cultured EBECs (adhesion to culture support, growth rate, differentiation rate) as compared to our previously described EBEC mono-culture system, suggesting that cross-talk between epithelial cells and fibroblasts actually takes place in our current co-culture setup through paracrine signalling. The EBEC-EBF co-culture model described herein will offer the opportunity to investigate epithelial-mesenchymal cell interactions and underlying disease mechanisms in the equine airways, thereby leading to a better understanding of their relevance to pathophysiology and treatment of equine and human asthma.

Distribution and properties of cardiac and pulmonary ß-adrenergic receptors in corn snakes (Pantherophis guttatus) and Boa constrictor (Boa constrictor).

The aim of the present study was to characterize ß-adrenergic receptors in the snake heart and lung of corn and Boa constrictor snakes. The ß-adrenergic receptor binding sites were studied in purified heart and lung membranes using the specific ß-adrenergic receptor antagonist [125J]-iodocyanopindolol (ICYP) and subtypes using selective ß1-adrenergic receptor antagonist CGP-20712A and selective ß2-adrenergic receptor antagonist ICI-118.551. A saturable and specific ß-adrenergic receptor binding site was detected in cardiac membranes with maximal receptor density (Bmax) of 43.99 ±â€¯3.86 fmol/mg protein (corn snake) and 58.07 ±â€¯2.88 fmol/mg protein (Boa constrictor) as well as KD of 24.21 ±â€¯7.38 pM (corn snake) and 21.48 ±â€¯3.85 pM (Boa constrictor) and in lung membranes (Bmax fmol/mg protein: 55.95 ±â€¯16.28 (corn snake) and 107.00 ±â€¯14.21 (Boa constrictor); KD pM: 71.25 ±â€¯21.92 (corn snake) and 55.04 ±â€¯18.68 (Boa constrictor)). Competition-binding studies showed ß-adrenergic receptors with low affinities to the ß2-selective adrenergic receptor antagonist and high affinity binding to ß1-selective adrenergic receptor antagonist in both heart and lung tissues of both snake species, suggesting the presence of high population of the post-synaptic ß1-adrenergic receptor subtype. It seems that the presence of the predominant ß1-subtype also in lung tissues may indicate the importance of the vascular system in the snake lung.

Modulation of TNF-α, IL-1Ra and IFN-γ in equine whole blood culture by glucocorticoids.

Glucocorticoids are important drugs in the treatment of many inflammatory, autoimmune and allergic diseases in humans and animals. We investigated the effects of hydrocortisone and dexamethasone on TNF-α, IL-1Ra and INF-γ release in stimulated whole blood cell culture from healthy horses. Whole blood cell cultures proved to be useful for the characterization of the anti-inflammatory properties of new drugs. Diluted equine whole blood was exposed to lipopolysaccharide (LPS) and PCPwL (a cocktail consisting of phythemagglutinin E, concanavalin A, pokeweed mitogen and lipopolysaccharide) in the presence or absence of hydrocortisone and dexamethasone (10-12 - 10-5 M). TNF-α and IL-1Ra (LPS) as well as IFN-γ (PCPwL) levels were measured in the supernatants using specific enzyme-linked immunosorbent assay (ELISA). The LPS-induced TNF-α and IL-1Ra as well as the PCPwL-induced IFN-γ levels were more potently suppressed by dexamethasone than by hydrocortisone in a concentration-dependent manner. Dexamethasone inhibited TNF-α, IL-1Ra and IFN-γ with the half maximal inhibition concentration (IC50) values of 0.09 µM, 0.453 µM and 0.001 µM, respectively, whereas hydrocortisone inhibited these cytokines with lower IC50 values of 1.45 µM, 2.96 µM and 0.09 µM, respectively. Our results suggest that the equine whole blood test system is useful and reliable to evaluate drug effects and immunological alterations and offers several advantages including simple and cheap performance in physiological and pathological conditions.

Pharmacokinetic evaluation of a transdermal anastrozole-in-adhesive formulation.

BACKGROUND AND OBJECTIVE: Anastrozole is a well-established active pharmaceutical ingredient (API) used for the treatment of hormone-sensitive breast cancer (BC) in postmenopausal women. However, treatment with the only available oral formulation is often associated with concentration-dependent serious side effects such as hot flashes, fatigue, muscle and joint pain, nausea, diarrhea, headache, and others. In contrast, a sustained-release system for the local application of anastrozole should minimize these serious adverse drug reactions. METHODS: Anastrozole-in-adhesive transdermal drug delivery systems (TDDS) were developed offering efficient loading, avoidance of inhomogeneity or crystallization of the drug, the desired controlled release kinetics, storage stability, easy handling, mechanical stability, and sufficient stickiness on the skin. In vitro continuous anastrozole release profiles were studied in Franz diffusion cells. In vivo, consecutive drug plasma kinetics from the final anastrozole transdermal system was tested in beagle dogs. For drug analysis, a specific validated liquid chromatography- mass spectrometry method using fragment ion detection was developed and validated. RESULTS: After efficient drug loading, a linear and sustained 65% drug release from the TDDS over 48 h was obtained. In vivo data showed a favorable anastrozole plasma concentration-time course, avoiding side effect-associated peak concentrations as obtained after oral administration but matching therapeutic plasma levels up to 72 h. CONCLUSION: These results provide the basis for establishing the transdermal application of anastrozole with improved pharmacokinetics and drug safety as novel therapeutic approach and promising option to treat human BC by decreasing the high burden of unwanted side effects.

Breed-related differences in age-dependent down-regulation of the ß1-adrenoceptor and adenylate cyclase activity in atrial and ventricular myocardium of Cröllwitzer ("wild-type") turkeys.

In conventional meat-type (British United Turkey (B.U.T.) Big 6) turkey hearts, it has been shown that all cardiac chambers exhibit down-regulation of the ß1-adrenoceptors (ß1-AR) and concomitantly cAMP accumulation with increasing age regardless of sex. In this study we proved the hypothesis that breed differences exist in age-dependent alterations in the ß1-AR system. Right (RA) and left (LA) atrial as well as right (RV) and left (LV) ventricular tissues were collected from male and female Cröllwitzer "wild-type" turkey poults of increasing age (6 wk, 12 wk, 16 wk, 21 wk). The ß1-AR density and function were quantified by (-)-[125I]-iodocyanopindolol (ICYP) radioligand binding analysis in cell membranes from 4 cardiac chambers. Basal and stimulated cAMP production was determined as indicator of the receptor function. Wild-type turkeys showed significantly higher heart to body weight ratio than the meat-type B.U.T. Big 6 turkeys. In both sexes of Cröllwitzer turkey hearts, the ß1-AR density decreased with age but significance was reached in male cardiac chambers. The receptor affinity (KD) and subtype distribution were not altered. Sex had no effect on age-related decrease in receptor density but had an effect on adenylate cyclase (AC) activity and subsequently cAMP production. In male Cröllwitzer turkey hearts of all ages, cAMP remained at same level, whereas this was even increased in female cardiac chambers. Thus, breed affected age-related receptor-, G-protein and AC-stimulated cAMP formation in normal ventricles and atria, with females exhibiting pronounced increase with age. This suggests that the receptor signaling in wild-type turkey hearts is not as blunted as in hearts of meat-type turkey poults in which stressful farming conditions and fast growing lead to receptor down-regulation.

Influence of Mechanical Circulatory Support on Endothelin Receptor Expression in Human Left Ventricular Myocardium from Patients with Dilated Cardiomyopathy (DCM).

BACKGROUND: In terminal failing hearts ventricular assist devices (VAD) are implanted as a bridge to transplantation. Endothelin receptor (ETR) antagonists are used for treatment of secondary pulmonary hypertension in VAD patients. However, the cardiac ETR regulation in human heart failure and during VAD support is incompletely understood. METHODS: In paired left ventricular samples of 12 dilated cardiomyopathy patients we investigated the density of endothelin A (ETA) and B (ETB) receptors before VAD implantation and after device removal. Left ventricular samples of 12 non-failing donor hearts served as control. Receptor quantification was performed by binding of [125I]-ET-1 in the presence of nonselective and ETA selective ETR ligands as competitors. Additionally, the ETR mRNA expression was analyzed using quantitative real-time-PCR. RESULTS: The mRNA of ETA but not ETB receptors was significantly elevated in heart failure, whereas total ETR density analyzed by radioligand binding was significantly reduced due to ETB receptor down regulation. ETA and ETB receptor density showed poor correlation to mRNA data (spearman correlation factor: 0.43 and 0.31, respectively). VAD support had no significant impact on the density of both receptors and on mRNA expression of ETA whereas ETB mRNA increased during VAD. A meta-analysis reveals that the ETA receptor regulation in human heart failure appears to depend on non-failing hearts. CONCLUSIONS: In deteriorating hearts of patients suffering from dilated cardiomyopathy the ETA receptor density is not changed whereas the ETB receptor is down regulated. The mRNA and the proteins of ETA and ETB show a weak correlation. Non-failing hearts might influence the interpretation of ETA receptor regulation. Mechanical unloading of the failing hearts has no impact on the myocardial ETR density.

Release kinetics of tumor necrosis factor-α and interleukin-1 receptor antagonist in the equine whole blood.

BACKGROUND: Horses are much predisposed and susceptible to excessive and acute inflammatory responses that cause the recruitment and stimulation of polymorphnuclear granulocytes (PMN) together with peripheral blood mononuclear cells (PBMC) and the release of cytokines. The aim of the study is to develop easy, quick, cheap and reproducible methods for measuring tumor necrosis factor alpha (TNF-α) and interleukin-1 receptor antagonist (IL-1Ra) in the equine whole blood cultures ex-vivo time- and concentration-dependently. RESULTS: Horse whole blood diluted to 10, 20 and 50 % was stimulated with lipopolysaccharide (LPS), PCPwL (a combination of phytohemagglutinin E, concanavalin A and pokeweed mitogen) or equine recombinant TNF-α (erTNF-α). TNF-α and IL-1Ra were analyzed in culture supernatants, which were collected at different time points using specific enzyme-linked immunosorbent assays (ELISA). Both cytokines could be detected optimal in stimulated 20 % whole blood cultures. TNF-α and IL-1Ra releases were time-dependent but the kinetic was different between them. PCPwL-induced TNF-α and IL-1Ra release was enhanced continuously over 24-48 h, respectively. Similarly, LPS-stimulated TNF-α was at maximum at time points between 8-12 h and started to decrease thereafter, whereas IL-1Ra peaked later between 12-24 h and rather continued to accumulate over 48 h. The equine recombinant TNF-α could induce also the IL-1Ra release. CONCLUSIONS: Our results demonstrate that similar to PCPwL, LPS stimulated TNF-α and IL-1Ra production time-dependently in whole blood cultures, suggesting the suitability of whole blood cultures to assess the release of a variety of cytokines in health and diseases of horse.

Differential regulation of the ß-adrenoceptor density and cyclic AMP level with age and sex in turkey cardiac chambers.

Decreased responses of the heart to ß-adrenoceptor stimulation with aging have been shown to occur merely in selected heart chambers in relation to increased catecholamine levels. However, there are no systematic studies that investigate all cardiac chambers with regard to receptor density and cAMP (adenosine 3', 5'-cyclic monophosphate) responses. We used meat-type turkey poults (British United Turkey (B.U.T.) Big 6) with increasing age because their heart seems to decrease in weight in relation to body weight and they are often used as an animal model for heart failure. The receptor density and distribution were quantified by radioligand binding analysis using (-)-[(125)I]-iodocyanopindolol and ß-adrenoceptor subtype-specific antagonists (ICI 118.551 and CGP 20712 A) in membranes of four cardiac chambers (right and left atria and ventricles) of 6-week-, 12-week-, 16/21-week-, and 57-week-old B.U.T. BIG 6 turkeys. Receptor function was determined by measuring basal and stimulated cAMP production. In both sexes, the ß-adrenoceptor density decreased significantly in all chambers with age without altered ß-adrenoceptor subtype distribution. The receptor affinity (KD) to the radioligand was similar in hearts of all age groups. ß-adrenoceptor-(isoproterenol and guanosine 5'-triphosphate), G-protein-(NaF) and catalytic unit of adenylate cyclase (forskolin, Mn(2+)) mediated cAMP responses were not chamber-dependent. Indeed, the cAMP level was significantly lower in 57-week-old hearts than in 6-week-, 12-week-, 16/21-week-old hearts. These data suggest that with increasing age and body weight, the ß-adrenoceptor signal transduction pathway was highly blunted in all cardiac chambers, occurring by decreased receptor density and cAMP responses.

The importance of muscarinic receptors in domestic animal diseases and therapy: Current and future perspectives.

This review provides an overview of the early and current literature including contributions that highlight the parasympathetic cholinergic receptor systems in domestic animal tissues. Muscarinic acetylcholine receptors (mAChRs) belong to the subfamily of G protein-coupled receptors and regulate many fundamental functions of the central and peripheral nervous systems and have been subject to research over at least 40 years. Nonetheless, there are few studies specifying mAChRs in domestic animal tissues. This review focuses on the pharmacology of muscarinic acetylcholine receptor (mAChR) system and its pathological as well as the therapeutic importance in organ systems of domestic animals. Illustration and discussion of recent advances in distribution, function, biochemistry and pharmacology of mAChRs are followed by summaries of the involvement of this family of receptors in cardiovascular, respiratory, neurological, gastrointestinal (GI) and urological diseases as well as in anaesthesia and toxicology. Specific functions of mAChRs are described in detail including subtype characterization, smooth muscle functions, signal transduction and regulation. Due to their wide tissue distribution, mAChRs have shown promise as targets for the treatment of some animal diseases such as equine recurrent airway obstruction, glaucoma, abnormalities of gastric acid secretion and GI disturbances including colic.

[Investigations on the acute, carrageenan-induced inflammatory reaction and pharmacology of orally administered sodium salicylate in turkeys]. / Untersuchungen zur akuten, Karrageen-induzierten Entzündungsreaktion sowie der Pharmakologie oral applizierten Natriumsalicylats bei Puten.

The complex mechanisms of acute inflammation have been subject to veterinary investigations since a long time. However, knowledge on the role of specific inflammatory mediators, as well as pharmacokinetics (PK) and -dynamics (PD) of non-steroidal anti-inflammatory drugs (NSAID) in birds is limited. The objective of this work therefore was to establish a modified tissue cage-model to investigate the acute, carrageenan-mediated inflammatory response, as well as plasma and exudate-kinetics and the antiphlogistic effect of orally administered sodium salicylate on the elicited inflammatory reaction in turkeys. Within the class Aves, comparable studies have so far only been published in chicken. Following bilateral subcutaneous implantation of carrageenan-treated synthetic sponges in the lateral thoracic region, sodium salicylate was administered orally at a dose of 50 mg/kg body weight (BW; therapy group) twice daily on three consecutive days, while a control group received drinking water as a placebo (n = 24 per group). Combined PK and PD of sodium salicylate were evaluated on the basis of salicylate- and prostaglandin (PG) E2-plasma- and -exudate-concentrations, exudate volumes, as well as leukocyte exudate counts. Sodium salicylate was readily absorbed from the gastrointestinal tract and accumulated in the inflammatory exudate. At 4, 6, and 10 h after first application, sodium salicylate significantly reduced PG E2-concentrations in the inflammatory exudate when compared to the control group, whereas leukocyte exudate counts increased over time in both study groups, unaffected by sodium salicylate The described modified tissue cage-model can be beneficial for further research on the pathophysiology of avian inflammatory processes and the investigation of the combined pharmacodynamics and -kinetics of drugs in birds of adequate size.

Characterization of ß-adrenergic receptors in the heart chambers of adult turkeys.

The presence, distribution and characteristics of chamber-specific ß-adrenergic receptors in adult turkey hearts were investigated by radioligand binding studies using (-)-[(125)I]-iodocyanopindolol (ICYP). The ß1-selective (CGP 20712A) and ß2-selective (ICI 118.551) antagonists as well as the nonselective ß-agonists isoproterenol, epinephrine and norepinephrine were used in displacement studies. In all cardiac chambers, ICI 118.551 and CGP 20712A displacement curves were monophasic and steep, with the affinity of CGP 20712A higher than that of ICI 118.551, indicating the exclusive presence of the ß1-adrenergic receptor subtype. The agonist rank order of potency was isoproterenol > norepinephrine ≥ epinephrine, typical for the ß1-receptor subtype. In all chambers, the density of ß-adrenergic receptors was ~40 fmol/mg protein and the KD was ~30 pM. The study revealed similar ß-adrenergic receptor density mainly of the ß1-subtype in all cardiac chambers, indicating that this receptor subtype could contribute equally to regulate cardiac physiological function and pathophysiology.