RESUMEN
The aim of the study was to investigate the renal function in clinically normal dogs receiving meloxicam and pimobendan alone or in combination. Ten adult female beagle dogs were administered the treatment for 7 days in a randomized crossover trial (control/meloxicam/pimobendan/meloxicam and pimobendan). Renal function was assessed by blood urea, creatinine, sodium, potassium and chloride concentrations and by glomerular filtration rate, measured by means of renal scintigraphy [renal uptake of (99m)Tc-diethylenetriaminepentacetic acid (DTPA)] and plasma clearance of (99m)Tc-DTPA. As compared with the control group, renal uptake and plasma clearance of (99m)Tc-DTPA were not significantly modified after a 7-day period of treatment with meloxicam or pimobendan alone, or meloxicam and pimobendan in combination. Furthermore, urea, creatinine, sodium, potassium and chloride levels in the serum of the dogs during the 7-day period treatment were not significantly modified in relation to the treatments. It was therefore concluded that meloxicam and pimobendan alone or in combination did not alter renal function in healthy dogs.
Asunto(s)
Antiinflamatorios no Esteroideos/farmacología , Perros/metabolismo , Riñón/efectos de los fármacos , Piridazinas/farmacología , Tiazinas/farmacología , Tiazoles/farmacología , Administración Oral , Animales , Antiinflamatorios no Esteroideos/administración & dosificación , Antiinflamatorios no Esteroideos/sangre , Creatinina/sangre , Estudios Cruzados , Femenino , Tasa de Filtración Glomerular/efectos de los fármacos , Riñón/diagnóstico por imagen , Meloxicam , Piridazinas/administración & dosificación , Piridazinas/sangre , Cintigrafía , Pentetato de Tecnecio Tc 99m , Tiazinas/administración & dosificación , Tiazinas/sangre , Tiazoles/administración & dosificación , Tiazoles/sangre , Urea/sangreRESUMEN
Isolated mouse vas deferens preparations were used to study the effect of temperature on noradrenaline-induced contractions. Preparations were suspended in the organ bath containing Krebs-Henseleit solution for isometric tension recording. Contractile responses to noradrenaline were investigated in the mouse vas deferens after moderate cooling from 37 to 26 or 22 degrees C. A significant increase of the phasic contractions to noradrenaline was observed at 26 or 22 degrees C compared with responses obtained at 37 degrees C (about 12.3 and 35.6% increase at 26 and 22 degrees C, respectively). The secondary noradrenaline-induced sustained contraction was also significantly enhanced after moderate cooling to 26 degrees C. The potentiation of noradrenaline-induced contraction at 26 degrees C remained in a Ca(2+)-free EGTA (1 mM)-containing solution. However, sustained contraction was suppressed after removal of the calcium from the medium at 37 and 26 degrees C. Contraction to caffeine was significantly enhanced at 22 degrees C compared with 37 degrees C. By contrast, barium chloride-induced contraction of the vas deferens was markedly decreased after moderate cooling to 22 degrees C. In the presence of ouabain (0.1 mM), the noradrenaline-induced peak contraction was significantly increased at 37 degrees C. However, potentiation of the noradrenaline response at 22 degrees C was unaffected by the Na+/K+ pump inhibitor. Noradrenaline-induced peak contractions were depressed in the presence of vanadate (1 mM) and cyclopiazonic acid (10 microM), two Ca(2+)-ATPase inhibitors, at 37 degrees C and also at 22 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Calcio/metabolismo , Frío , Inhibidores Enzimáticos/farmacología , Músculo Liso/fisiología , Norepinefrina/farmacología , Conducto Deferente/fisiología , Animales , Compuestos de Bario/farmacología , Cafeína/farmacología , ATPasas Transportadoras de Calcio/antagonistas & inhibidores , Cloruros/farmacología , Indoles/farmacología , Contracción Isométrica/efectos de los fármacos , Masculino , Ratones , Músculo Liso/efectos de los fármacos , Ouabaína/farmacología , ATPasa Intercambiadora de Sodio-Potasio/metabolismo , Vanadatos/farmacología , Conducto Deferente/efectos de los fármacos , Conducto Deferente/metabolismoRESUMEN
In the present study we have investigated the involvement of sensitized mice immunoglobulins and some electrophysiological alterations that participate to the antigenic sensitization-induced hyperreactivity of isolated mouse vas deferens. Active sensitization was performed by subcutaneous injection of egg albumen. Contractile responses to noradrenaline were isometrically recorded in the isolated vas deferens. Low external Na(+)-induced contractions and rapid cooling contractures were evaluated. Resting membrane potential (Er) and intracellular Na activity were measured in control and actively sensitized vas deferens by using conventional KCl-filled and Na(+)-sensitive microelectrodes respectively. Active sensitization-induced hyperreactivity to noradrenaline was reproduced by in vitro passive sensitization of control vas deferens with sensitized mice immunoglobulins. The inhibition of the nitric oxide synthesis by N-nitro-L-arginine methyl ester (L-NAME) did not change control vas deferens reactivity in vitro to noradrenaline and acetylcholine. Rapid cooling contractures, performed after lowering external Na+ concentration, were not altered by active sensitization. However, sensitization increased significantly the strength of the low external Na+-induced contractions. In control vas deferens Er was a mean of -49.2+/-0.3 mV (mean+/-SEM). Sensitization resulted in reduction of Er by 14 mV. In sensitized preparations, relative insensitivity of Er to ouabain, external K+ removal and cooling were observed. The intracellular Na+ activity was increased by about 40% in sensitized vas deferens. It is concluded that sensitization-induced hyperreactivity is mediated by immunoglobulins and produced smooth muscle cells depolarisation. The low Er of sensitized muscle may be partly the result of an increase in membrane permeability to Na+ which could interfere with intracellular Ca2+ homeostasis.
Asunto(s)
Inmunoglobulinas/inmunología , Contracción Muscular/efectos de los fármacos , Sodio/metabolismo , Conducto Deferente/fisiología , Animales , Calcio/metabolismo , Homeostasis , Inmunización , Masculino , Potenciales de la Membrana , Ratones , NG-Nitroarginina Metil Éster/farmacología , Norepinefrina/farmacología , ATPasa Intercambiadora de Sodio-Potasio/fisiología , Conducto Deferente/efectos de los fármacosRESUMEN
The aims of this study was to characterize the functional response of atypical beta-adrenoceptors (beta-AR) in rat aorta and to investigate whether this relaxation was altered before and during the development of hypertension. Aortic rings from 4 or 12 weeks old Wistar Kyoto (WKY) rats or spontaneously hypertensive rats (SHR) were placed in organ baths and constricted with phenylephrine. Then, cumulative concentration-relaxation curves to the beta-AR agonists were constructed. In intact aortic rings from 12 weeks old WKY rats, CGP 12,177 (CGP) and cyanopindolol (partial beta 3-AR agonists and atypical beta-AR agonists with beta 1/beta 2-AR antagonist properties) produced concentration-dependent relaxation (pD2 = 5.09 +/- 0.03; Emax = 60.4 +/- 2.5%; n = 9; pD2 = 6.17 +/- 0.05; Emax = 95.9 +/- 1%; n = 5 respectively). The endothelium removal did not modify this relaxation. In 12 weeks old WKY rats, the endothelium-independent relaxation to CGP was not modified in the presence of nadolol (beta 1/beta 2-AR antagonist) or L-748 337 (beta 3-AR antagonist) excluding the participation of beta 1, beta 2 et beta 3-AR in this effect. By contrast, this relaxation was significantly inhibited by CGP 20712A or bupranolol, atypical beta-AR antagonists at high concentrations. In 12 weeks old SHR, endothelium-independent relaxation to CGP or cyanopindolol was greatly inhibited. In order to sought out whether impairment of atypical beta-AR-mediated relaxation was due to hypertension, experiments were performed in 4 weeks old SHR. At this age, CGP-induced relaxation was greatly inhibited compared to that obtained in age-matched WKY rats. In 12 weeks old SHR pretreated with pertussis toxin (10 micrograms/kg i.p./3 days), the relaxant effect to CGP was partly restored. We conclude that the atypical beta-AR were functionally expressed in aortic vascular smooth muscle cells of rat aorta. In 4 or 12 weeks old SHR rats, atypical beta-AR-mediated relaxation was impaired, suggesting that this dysfunction occurs before the establishment of hypertension. Gi proteins may be one of the factors that contributes to this impairment.
Asunto(s)
Aorta/fisiología , Endotelio Vascular/fisiología , Hipertensión/fisiopatología , Receptores Adrenérgicos beta/fisiología , Agonistas Adrenérgicos beta/farmacología , Animales , Propanolaminas/farmacología , Ratas , Ratas Endogámicas SHR , Ratas WistarRESUMEN
The aim of this study was to investigate the involvement of beta 3-adrenoceptors (beta 3-AR) in hypertension. Aortic rings were isolated from 12 weeks old WKY (Wistar-Kyoto) and SHR (spontaneously hypertensive rat) rats. Rings were placed in organ baths and constricted with phenylephrine. Then, cumulative concentration-relaxation curves to the beta 3-AR agonists were constructed. In both strains, SR58611, a preferential beta 3-agonist, produced similar concentration-dependent relaxation. CGP 12177 (CGP), (a partial beta 3-AR and atypical beta-AR agonist with beta 1-/beta 2-AR antagonistic properties) produced similar relaxation in WKY (pD2 = 5.10 +/- 0.06; Emax = 54 +/- 2%; n = 6) and in SHR (pD2 = 4.98 +/- 0.02; Emax = 58 +/- 4%; n = 6). In WKY, relaxant response to CGP was not modified by nadolol (10 microM) or L-748.337 (3 microM) suggesting an atypical beta-AR activation. By contrast, in SHR, the effect of CGP was strongly decreased by 3 microM L-748.337 (Emax = 27.8 +/- 5.4%; n = 7; p < 0.05 vs CGP alone), suggesting a possible participation of beta 3-AR in CGP-induced relaxation. In order to investigate the role of endothelium in CGP-induced relaxation, experiments were performed in denuded aortic rings. In WKY, CGP-induced relaxation was not modified by endothelium removal, by contrast, this was greatly inhibited in SHR (Emax = 18.3 +/- 1.9%; n = 9; p < 0.05 vs CGP in intact aortic rings). Endothelium-independent relaxation to CGP was resistant to nadolol or L-748.337 treatment which seems to rule out the involvement of beta 1, beta 2 and beta 3-AR. Endothelium-independent relaxation to CGP was significantly reduced by SQ 22536 or MDL 12330A, non-selective adenylyl cyclase inhibitors, indicating a role of cAMP-dependent pathway in CGP response. By contrast, the relaxant effect to CGP was not modified by SQ 22536 in SHR. In conclusion, these results show that [1] functional response to beta 3-AR stimulation was not altered in hypertension [2]. CGP activated an atypical beta-AR distinct from beta 1, beta 2 and beta 3-AR, partly through cAMP-dependent pathway. Impaired atypical beta-AR relaxation to CGP in SHR could contribute to the pathogenesis of the hypertension.
Asunto(s)
Hipertensión/fisiopatología , Receptores Adrenérgicos beta 3/fisiología , Receptores Adrenérgicos beta/fisiología , Animales , Técnicas de Cultivo , Endotelio Vascular/fisiología , Hipertensión/veterinaria , Ratas , Ratas Endogámicas SHRRESUMEN
Autoantibodies against ß1-adrenoceptors (ß1-ARs) have been detected in the serum of patients with various cardiac diseases; however, the pathological impact of these autoantibodies (ß1-AABs) has only been evaluated in cardiac tissue. The purpose of the present study was to evaluate whether ß1-AABs have deleterious effects on vascular reactivity in rats. An enzyme-linked immunosorbent assay was used to detect ß1-AABs in sera from immunized rats over a period of 1-3 months using the peptidic sequence of the second extracellular loop of human ß1-AR. Functional studies were performed in thoracic aortic (TA) and small mesenteric artery (SMA) rings from immunized rats. Following pre-contraction with phenylephrine (0.3 µM and 3 µM for the TA and SMA respectively), cumulative concentration-response curves (CCRCs) to various ß-AR agonists (isoproterenol, dobutamine, salbutamol, SR 58611A), acetylcholine, A23187, and sodium nitroprusside (SNP) were then plotted. The relaxations induced by dobutamine, SR 58611A, and acetylcholine were significantly impaired, but salbutamol-induced relaxations were not affected, in both vessels from immunized rats. A significant impairment of isoproterenol-induced relaxation was only observed in SMA. CCRCs to SNP were not modified in either of the vessels. A23187-induced relaxation was impaired in immunized rats. Following pretreatment with L-arginine, vasorelaxation to acetylcholine and SR 58611A was restored in immunized rats. This study demonstrates that immunization against the second extracellular loop of ß1-ARs has a deleterious impact on vasorelaxations in the TA and SMA of rats, involving alterations in endothelium-dependent NO signaling pathways.
Asunto(s)
Anticuerpos/farmacología , Aorta Torácica/efectos de los fármacos , Arterias Mesentéricas/efectos de los fármacos , Péptidos/farmacología , Receptores Adrenérgicos beta 1/inmunología , Antagonistas Adrenérgicos beta/farmacología , Animales , Aorta Torácica/fisiología , Endotelio Vascular/efectos de los fármacos , Inmunización , Inmunoglobulina G/inmunología , Masculino , Arterias Mesentéricas/fisiología , Conformación Proteica , Ratas , Ratas Wistar , Receptores Adrenérgicos beta 1/química , Vasodilatación/efectos de los fármacosRESUMEN
The direct vasodilatory action of pentoxifylline (1-(5-oxohexyl)-3,7-dimethylxanthine) and its signalling pathway was evaluated in equine digital veins. Cumulative concentration-response curves to pentoxifylline (1 nM to 300 µM) were recorded in phenylephrine-precontracted equine digital vein rings under different experimental conditions. Relaxation to pentoxifylline was partially inhibited by endothelium removal, but was unaltered by CGS-15943 (a non-xanthine adenosine receptor antagonist; 3 µM). Nitric oxide synthase (NOS), soluble guanylate cyclase and cyclooxygenase (COX) inhibitors (Nω-nitro-L-arginine methyl ester (100 µM), ODQ (30 µM) and indomethacin (10 µM), respectively) significantly reduced the maximum relaxation induced by pentoxifylline. Moreover, pentoxifylline-induced relaxation was strongly reduced by Rp-8-Br-PET-cyclic guanosine monophosphate-S (a protein kinase G inhibitor; 3 µM), but remained unaffected by H-89 (a protein kinase A inhibitor; 2 µM). Pentoxifylline-induced relaxation was associated with a 3.4-fold increase in tissue cGMP content. To investigate whether pentoxifylline can affect cAMP- and cGMP-mediated relaxations, curves to forskolin, to sodium nitroprusside (SNP) and 8-bromo-cGMP were also recorded in endothelium-denuded equine digital vein rings pretreated with pentoxifylline (10 and 100 µM). Pentoxifylline only potentiated the SNP-mediated relaxation at the highest concentration (100 µM). Thus, pentoxifylline relaxed equine digital veins via endothelium-dependent and endothelium-independent components. The effect was mediated through both the NOS and COX pathways and could also result from inhibition of cGMP specific-phosphodiesterase activity at the highest concentrations used.
Asunto(s)
Caballos/fisiología , Pentoxifilina/farmacología , Vasodilatación/efectos de los fármacos , Vasodilatadores/farmacología , Venas/efectos de los fármacos , Animales , Colforsina/farmacología , GMP Cíclico/análogos & derivados , GMP Cíclico/farmacología , Relación Dosis-Respuesta a Droga , Endotelio Vascular/fisiología , Indometacina/farmacología , Nitroprusiato/farmacología , Técnicas de Cultivo de TejidosRESUMEN
PURPOSE: To evaluate the effect of active immunization with a peptide corresponding to the second extracellular loop of the human beta1-adrenoceptors (ß(1)-AR) on the reactivity of Wistar rat isolated aorta. METHODS: Nine-week-old Wistar rats were actively immunized for 3months with a peptide corresponding to the second extracellular loop of the human ß(1)-AR. Specific immunoglobulins G (IgG) were characterized by Elisa and the bicinchonic acid protein assay and their functionality were tested in isolated ventricular cardiomyocytes (IVC) from control rats. Aortic rings isolated from control or immunized rats were mounted in organ baths. Then, contractile curves to phenylephrine (1nM to 300µM) and relaxant curves to acetylcholine (1nM to 100µM) and isoprenaline (1nM to 30µM) were established. RESULTS: Cell shortening increased dose-dependently in rat IVC superfused with IgG containing ß(1)-AR antibodies (10 or 25µg/mL). Isoprenaline-induced positive inotropy was strongly reduced in IgG containing ß(1)-AR antibodies preincubated (3h) IVC. Phenylephrine-and acetylcholine-induced aortic responses were greatly inhibited in immunized rats compared to control ones. However, active immunization did not influence the isoprenaline-mediated relaxation. CONCLUSIONS: The present work confirms that ß(1)-AR antibodies directed against the second extracellular loop of ß(1)-AR induce a positive inotropic effect in adult rat IVC. Moreover, we demonstrated, for the first time, that 3-month immunization with ß(1)-AR peptide was associated with altered aortic endothelial function without change in the ß-AR-mediated vasorelaxation.
Asunto(s)
Aorta , Autoanticuerpos/inmunología , Endotelio Vascular , Inmunoglobulina G/sangre , Receptores Adrenérgicos beta 1/inmunología , Acetilcolina/farmacología , Agonistas Adrenérgicos beta/farmacología , Algoritmos , Animales , Aorta/efectos de los fármacos , Gráficos por Computador , Modelos Animales de Enfermedad , Endotelio Vascular/efectos de los fármacos , Humanos , Técnicas In Vitro , Isoproterenol/farmacología , Masculino , Miocitos Cardíacos/efectos de los fármacos , Fenilefrina/farmacología , Ratas , Ratas Wistar , Vasoconstrictores/farmacología , Vasodilatadores/farmacologíaRESUMEN
The aim of this in vitro study was to compare the uterokinetic activity of oxytocin and dinoprost, the natural PGF2α, with or without aglepristone, in canine myometrial fibers. Thirty-three bitches were allocated into one of four groups, depending on their estrous stage and whether or not they had received a treatment with aglepristone (metestrus aglepristone, n = 5; metestrus without treatment, n = 9; anestrus aglepristone, n = 9; anestrus without treatment, n = 10). After hysterectomy, longitudinal and circular uterine strips were mounted in organ baths. Oxytocin or PGF2α (10 nmol/l to 10 micromol/l) were applied non-cumulatively. A linear mixed effects models theory was used to compare the fiber effect, the aglepristone effect, and the treatment effect, from the area under the curves calculated from the contractile effect/concentration curves for each drug. Oxytocin and PGF2α induced concentration-dependent myometrial contractions in longitudinal (LF) and circular myometrial fibers (CF), indicating the presence of functional contractile oxytocin- and PGF2α-receptors in metestrus and anestrus. The contractile response to oxytocin was greater in LF than in CF in all of the groups; the response to PGF2α was greater in LF than in CF in non-treated bitches in anestrus and in treated bitches in metestrus. These results suggest that there is a difference in sensitivity or a heterogeneous distribution of oxytocin and PGF2α-receptors in the myometrial layers, which is independent of hormonal impregnation. The contractile response to oxytocin and PGF2α was significantly increased after aglepristone treatment in LF during metestrus, suggesting that the progesterone withdrawal induced by aglepristone has a role to play. The longitudinal myometrial layer also appeared to be the target for the two drugs at this stage. This study provides new information about canine uterine contractile activity, notably the differing behavior of myometrial CF and LF; in vivo studies are required to test the use of a combination of aglepristone and oxytocin in the treatment of canine pyometra.
Asunto(s)
Dinoprost/farmacología , Perros/fisiología , Estrenos/farmacología , Estro/fisiología , Oxitócicos/farmacología , Oxitocina/farmacología , Contracción Uterina/efectos de los fármacos , Animales , Femenino , Técnicas In Vitro , Miometrio/efectos de los fármacos , Miometrio/fisiología , Progesterona/sangreRESUMEN
OBJECTIVES: This study in swine assessed BIS stability in response to decreases and increases in cardiac output under two propofol/remifentanil dosage combinations, both producing the same depth of surgical anaesthesia. METHODS: Eight anaesthetized-paralyzed ventilated adult swine were studied using a random-order cross-over design. Four received a P low/R high combination (P, 8.4+/-0.9 mg/kg/h; and R, 0.54+/-0.02 microg/kg/min) and then a P high/R low combination (P, 26.7+/-2.1mg/kg/h; and R, 0.34+/-0.01 microg/kg/min). The other four had these two combinations in the reverse order. Under each P/R combination, and after a 60-minutes steady state, a 15-minute stable cardiac tamponade was induced by intrapericardial gelatine infusion. Then, after returning to pre tamponade condition, a 15 minutes period with dobutamine was allowed. RESULTS: Tamponade induced falls in average mean arterial pressure (MAP) (from 79+/-18 to 47+/-9 mm Hg; p<0.05) and cardiac output (Qc) (from 1.90+/-0.46 l/min to 1.20+/-0.38 l/min, p<0.05). Conversely, dobutamine increased both MAP and Qc (p<0.05). During each type of hemodynamic challenges, changes in anaesthesia depth as assessed by BIS differed dramatically between the two drug combinations, despite observing the same percent change in P and R effect-site concentration. With P high/R low and tamponade, BIS fell from 65+/-5 to 29+/-10 (p<0.05); dobutamine produced opposite effects. With P low/R high, in contrast, BIS was not influenced by either of the hemodynamic challenges. CONCLUSION: Conversely to a high propofol/low remifentanil combination, a low propofol/high remifentanil combination allows constant anaesthetic depth in the face of haemodynamic challenges.
Asunto(s)
Analgésicos Opioides/farmacología , Taponamiento Cardíaco/inducido químicamente , Taponamiento Cardíaco/fisiopatología , Cardiotónicos/farmacología , Dobutamina/farmacología , Electroencefalografía/efectos de los fármacos , Hipnóticos y Sedantes/farmacología , Anestesia Intravenosa , Anestésicos Intravenosos/farmacología , Animales , Presión Sanguínea/efectos de los fármacos , Gasto Cardíaco/efectos de los fármacos , Combinación de Medicamentos , Monitoreo Intraoperatorio , Piperidinas/farmacología , Propofol/farmacología , Remifentanilo , PorcinosRESUMEN
The objective of this study was to investigate renal function in clinically normal dogs receiving tepoxalin, a nonsteroidal inflammatory drug, either in association with or without an angiotensin-converting enzyme inhibitor (ACEI). Ten adult female Beagle dogs were used in the three phases of the study. The dogs were administered the drugs once daily for 7 days (experiment 1: placebo/tepoxalin/tepoxalin and benazepril; experiment 2: enalapril/tepoxalin and enalapril) or for 28 days (experiment 3: tepoxalin and benazepril together). Renal function was assessed by measurement of glomerular filtration rate (GFR) by renal scintigraphy [(renal uptake of 99mTc-diethylenetriaminepentacetic acid (DTPA)] and plasma clearance of 99mTc-DTPA. Compared with the placebo group, renal uptake and plasma clearance of 99mTc-DTPA were not significantly modified after a 7-day period of treatment with tepoxalin or enalapril alone, tepoxalin and benazepril or tepoxalin and enalapril together. No significant change was obtained in GFR after a 28-day period of dosing with tepoxalin and benazepril together. Therefore, it was concluded that tepoxalin did not alter renal function in healthy Beagle dogs receiving ACEI.
Asunto(s)
Inhibidores de la Enzima Convertidora de Angiotensina/farmacología , Antiinflamatorios no Esteroideos/farmacología , Riñón/efectos de los fármacos , Pirazoles/farmacología , Inhibidores de la Enzima Convertidora de Angiotensina/administración & dosificación , Animales , Antiinflamatorios no Esteroideos/sangre , Benzazepinas/administración & dosificación , Benzazepinas/farmacología , Perros , Quimioterapia Combinada , Enalapril/administración & dosificación , Enalapril/farmacología , Femenino , Tasa de Filtración Glomerular/efectos de los fármacos , Riñón/diagnóstico por imagen , Pruebas de Función Renal/veterinaria , Pirazoles/sangre , Cintigrafía , Radiofármacos , Pentetato de Tecnecio Tc 99mRESUMEN
1. Dose-response curves for noradrenaline, phenylephrine and clonidine were determined isometrically on the mouse vas deferens at 26 degrees C, 15 degrees C and compared to the one obtained at 37 degrees C. 2. In the presence of noradrenaline, reducing temperature induced an increase of both maximal developed tension and sensitivity to the drug. Reduction by 50% of the extracellular calcium concentration abolished the maximal contraction potentiation. 3. When reducing temperature to 26 degrees C, the maximal contraction was increased and depressed in the presence of phenylephrine and clonidine respectively. 4. The results suggest (a) that cooling increases the reactivity of mouse vas deferens by activation of alpha 1 adrenoceptors and depresses it by activation of alpha 2 adrenoceptors (b) that calcium ions could play an important role in the potentiation of the maximal contraction.
Asunto(s)
Frío , Simpatomiméticos/farmacología , Conducto Deferente/efectos de los fármacos , Animales , Calcio/fisiología , Clonidina/farmacología , Relación Dosis-Respuesta a Droga , Espacio Extracelular/metabolismo , Técnicas In Vitro , Isoproterenol/farmacología , Masculino , Ratones , Contracción Muscular/efectos de los fármacos , Músculo Liso/efectos de los fármacos , Músculo Liso/fisiología , Norepinefrina/farmacología , Fenilefrina/farmacología , Conducto Deferente/fisiologíaRESUMEN
The purpose of this study was to evaluate the strain-related differences in tracheal hyperresponsiveness in control and egg albumen-sensitized guinea pigs. Concentration-response curves to acetylcholine and barium chloride were established from tracheal rings of Dunkin-Hartley and BFA strain guinea pigs. In the Dunkin-Hartley strain, sensitization did not significantly increase the tracheal responsiveness to acetylcholine and barium chloride. By contrast, in the BFA strain, significant sensitization-induced hyperreactivity was achieved as the maximal contractions induced by acetylcholine and barium chloride, were enhanced from 6.5 +/- 1.2 and 3.2 +/- 0.4 mN in control to 10.0 +/- 1.4 and 5.6 +/- 0.8 mN, respectively, in sensitized animals. However, antigen challenge, performed in vitro, exhibited a similar amplitude of contraction in tracheal rings from both strains (Dunkin-Hartley 5.1 +/- 0.8 mN; BFA 5.9 +/- 0.5 mN). Finally, while the two guinea-pig strains developed specific sensitization to allergen, only tracheal rings from the BFA strain developed hyperresponsiveness to acetylcholine and barium chloride. The strain-related difference appears to be partly explained by a lower basal reactivity in the BFA strain both acetylcholine (Em 7.3 +/- 1.7 and 6.5 +/- 1.2 mN for Dunkin-Hartley and BFA, respectively) and barium chloride (Em 9.4 +/- 2.6 and 3.2 +/- 0.4 mN for Dunkin-Hartley and BFA, respectively). As the same procedure of sensitization provides different results in the genesis of hyperreactivity between the two guinea-pig strains used for asthma models, the BFA guinea-pig strain seems to be a better model because sensitized non-challenged animals could easily be dissociated from control ones, similar to that which occurs in asthmatic patients during provocation tests with cholinergic drugs.
Asunto(s)
Inmunización , Tráquea/fisiopatología , Acetilcolina/farmacología , Albúminas/administración & dosificación , Animales , Compuestos de Bario/farmacología , Cloruros/farmacología , Relación Dosis-Respuesta a Droga , Cobayas , Masculino , Contracción Muscular/efectos de los fármacos , Contracción Muscular/inmunología , Músculo Liso/efectos de los fármacos , Especificidad de la Especie , Tráquea/efectos de los fármacos , Tráquea/inmunologíaRESUMEN
Changes in the reactivity of the ileum (to histamine and barium chloride) and vas deferens (to acetylcholine and barium chloride), isolated from actively egg albumen-sensitized guinea pigs, have been investigated. The study was performed on 2 guinea pig strains: the Dunkin-Hartley strain, usually used as an airway allergic model, and the BFA strain. In actively sensitized guinea pigs of both strains, concentration-response curves exhibited a significant dose-dependent upward shift compared to those obtained in control guinea pigs. The maximal contraction strength calculated from these curves was significantly enhanced in both sensitized guinea pig strains, without a change in EC50 values. This study showed that the active antigen sensitization procedure involved several smooth muscle functions, and not exclusively the trachea.
Asunto(s)
Músculo Liso/efectos de los fármacos , Músculo Liso/inmunología , Acetilcolina/fisiología , Animales , Compuestos de Bario/farmacología , Cloruros/farmacología , Cobayas , Histamina/fisiología , Íleon/efectos de los fármacos , Íleon/inmunología , Inmunización , Técnicas In Vitro , Masculino , Contracción Muscular/efectos de los fármacos , Contracción Muscular/inmunología , Conducto Deferente/efectos de los fármacos , Conducto Deferente/inmunologíaRESUMEN
1. The present study was designed to investigate the effect of active sensitization on the responsiveness of mouse vas deferens before and after moderate cooling. Contractile responses to noradrenaline (NA) were isometrically recorded in the vas deferens of control and ovalbumen-sensitized mice at 37 degrees C and 22 degrees C. 2. Enhancement of the vas deferens reactivity to NA was observed in the sensitized vs control mice at 37 degrees C and 22 degrees C (P < 0.01). In sensitized mice, maximal contraction was significantly increased compared with controls, and sensitization-induced hyperresponsiveness was greater at 22 degrees C compared with 37 degrees C. At 37 degrees C, contractile responses to barium chloride were significantly enhanced in the sensitized mice compared with controls, whereas the reduction of the temperature to 22 degrees C produced a marked inhibition of vas deferens contractions in both groups. Caffeine-induced contractions of the vas deferens were similar in control and sensitized mice at 37 degrees C. After moderate cooling to 22 degrees C, vas deferens from sensitized mice became hyperresponsive compared with controls. 3. Ouabain (0.1 mM) produced an increase of NA-induced contraction in control and sensitized vas deferens at 37 degrees C (P < 0.01). It had no significant effect in the control at 22 degrees C but produced a marked inhibition of NA-induced contraction in the sensitized vas deferens at 22 degrees C. Contractions to NA in the presence of vanadate (1 mM) were depressed in control and sensitized mice at both temperatures. 4. These results suggest that sensitization-induced hyperresponsiveness of the mouse vas deferens is mediated by an increased mobilization of intracellular calcium. The involvement of an unknown ouabain-sensitive pathway in sensitization-induced alterations is also discussed.
Asunto(s)
Músculo Liso/efectos de los fármacos , Ovalbúmina/administración & dosificación , Conducto Deferente/efectos de los fármacos , Análisis de Varianza , Animales , Compuestos de Bario/farmacología , Cafeína/farmacología , Calcio/metabolismo , Estimulantes del Sistema Nervioso Central/farmacología , Cloruros/farmacología , Frío , Inhibidores Enzimáticos/farmacología , Contracción Isométrica/efectos de los fármacos , Masculino , Ratones , Músculo Liso/fisiología , Norepinefrina/farmacología , Ouabaína/farmacología , Distribución Aleatoria , Conducto Deferente/fisiologíaRESUMEN
BACKGROUND: Smooth muscles hyperresponsiveness is a common feature in anaphylaxis and allergic diseases. OBJECTIVE: The aim of the present work was to investigate the effect of in vitro passive sensitization with highly purified immunoglobulin G1 (IgG1) on the responsiveness of tracheal, aortic, vas deferens and ileum smooth muscles. METHODS: Firstly, IgG1, obtained from actively sensitized BFA guinea-pigs, was purified by Protein A-Sepharose column and characterized by enzyme-linked immunosorbent assay (ELISA) and immunoelectrophoresis analysis. Concentration-response curves to spasmogens (acetylcholine for trachea and vas deferens, noradrenaline for aorta and histamine for ileum) were established before and after in vitro passive sensitization with IgG1. RESULTS: Contractile responses and maximal contractions were significantly enhanced after passive sensitization for all the organs. Maximal contractions were significantly increased in the trachea (+46.7%), aorta (+51%), vas deferens (+114.2%) and ileum (+117.2%). At the end of the experiments, the application of the sensitizing antigen induced a significant Schultz-Dale reaction of the smooth muscles. CONCLUSION: The present results show that the in vitro application of purified IgG1 can produce non-specific smooth muscle hyperreactivity and hypersensitivity. So, IgG1 can be considered as the main factor involved in the genesis of sensitization-induced hyperresponsiveness, and probably play a great role in hyperreactivity observed during allergic diseases and anaphylaxis.
Asunto(s)
Inmunoglobulina G/farmacología , Contracción Muscular/inmunología , Músculo Liso/inmunología , Animales , Antígenos/inmunología , Aorta/efectos de los fármacos , Aorta/inmunología , Cromatografía de Afinidad , Electroforesis en Gel de Poliacrilamida , Cobayas , Íleon/efectos de los fármacos , Íleon/inmunología , Inmunización , Inmunoglobulina G/aislamiento & purificación , Masculino , Contracción Muscular/efectos de los fármacos , Músculo Liso/efectos de los fármacos , Tráquea/efectos de los fármacos , Tráquea/inmunología , Conducto Deferente/efectos de los fármacos , Conducto Deferente/inmunologíaRESUMEN
BACKGROUND: Vascular hyperresponsiveness can be reproduced by in vitro passive sensitization of isolated aorta with immunoglobulin G1 (IgG1) taken from ovalbumen-sensitized BFA guinea-pig. OBJECTIVE: The aim of the present work was to investigate the role of nitric oxide in the sensitization-induced alteration of the contractile and relaxant responses of guinea-pig aorta to noradrenaline (NA) and acetylcholine (ACh), respectively. METHODS: Cumulative concentration-response curves to NA or ACh were established before and after IgG1 sensitization and then after successive treatments. RESULTS: IgG1 in vitro passive sensitization of aorta caused a significant hyperreactivity to NA and completely inhibited the relaxation to ACh. After sensitization, the addition of an intact aortic ring (with endothelium) in the organ chamber restored the maximal response to NA and ACh close to control but was ineffective in the presence of hemoglobin. The restoration of the control reactivity to NA was also inhibited in the presence of L-NAME or when the added aortic ring was endothelium-denuded. Moreover, L-arginine, a nitric oxide (NO) precursor, was able to restore the control reactivity to NA. CONCLUSION: The present results show that IgG1 in vitro sensitization induced a loss of NO release from the vascular endothelium. This loss of NO probably plays a great role in vascular hyperreactivity by increasing the contractile response and decreasing the relaxant response to mediators and would be a component of allergic diseases pathogenesis.
Asunto(s)
Endotelio Vascular/metabolismo , Inmunoglobulina G/farmacología , Músculo Liso Vascular/metabolismo , Óxido Nítrico/metabolismo , Acetilcolina/farmacología , Animales , Aorta/efectos de los fármacos , Aorta/metabolismo , Endotelio Vascular/efectos de los fármacos , Cobayas , Técnicas In Vitro , Masculino , Músculo Liso Vascular/efectos de los fármacos , Norepinefrina/farmacologíaRESUMEN
Smooth muscles hyperresponsiveness is a common feature in anaphylaxis and allergic diseases. The aim of the present work was to investigate whether the enhanced reactivity of sensitized guinea-pig vas deferens was associated with changes in the resting membrane potential (Er) of the smooth muscle cells. Active sensitization was performed by subcutaneous injection of egg albumen. Er was measured in vitro in isolated vas deferens with conventional KCl-filled microelectrodes. Quantification of [3H]ouabain binding sites, measurements of 86Rb efflux, and measurements of Na and K contents were also performed. In normal physiological solution, at 35 degrees C, Er was a mean of -54.1+/-0.3 mV (mean +/- SEM) in control vas deferens. Sensitization resulted in depolarizing Er by about 7 mV. In control and sensitized preparations, the 3H-ouabain binding site concentration, the efflux of 86Rb, and the K content were similar. In guinea-pig vas deferens, active sensitization induced a partial depolarization of the resting membrane potential of the smooth muscle cells, which did not result from a downregulation of Na+ -K+ pump sites.