RESUMEN
1. It has been shown that opioid peptides modulate airway function. In the present study, the effect of beta-endorphin on antigen-induced contractions of isolated tracheal rings from actively sensitized guinea-pigs has been studied. 2. beta-Endorphin had a concentration-dependent bimodal effect on anaphylactic contractions of the trachea. Low concentrations of beta-endorphin (10(-10) and 10(-8) M) significantly potentiated anaphylactic contractions, whereas higher concentrations (10(-7) and 10(-6) M) significantly suppressed anaphylactic contractions of guinea-pig trachea. 3. beta-Endorphin in concentrations of 10(-8) M and 10(-7) M did not affect the responsiveness of the tracheal rings to histamine or leukotriene D4. This indicates that beta-endorphin does not influence the responsiveness of tracheal smooth muscle to anaphylactic mediators. 4. In the presence of the non-selective opioid receptor antagonist naloxone, 10(-8) M beta-endorphin still potentiated the anaphylactic contractions of the trachea. In addition, an equimolar concentration of des-Tyr1-beta-endorphin, a fragment of beta-endorphin without opioid-like activity, also potentiated anaphylactic contractions. The potentiation of anaphylactic contraction by 10(-8) M beta-endorphin is not therefore mediated by classical opioid-receptors. 5. In the presence of naloxone, 10(-7) M, beta-endorphin did not suppress anaphylactic contractions of the trachea. Thus, the suppression of anaphylactic contraction is mediated via a classical opioid-receptor. 6. In epithelium-denuded trachea, both 10(-8) and 10(-7) M beta-endorphin suppressed the anaphylactic contractions, whereas 10(-8) and 10(-7) M des-Tyr1-beta-endorphin did not affect anaphylactic contractions. It is concluded that the potentiation of the anaphylactic contraction in intact trachea is epithelium-dependent whereas the suppression of the anaphylactic contraction is epithelium-independent.
Asunto(s)
Anafilaxia/fisiopatología , Músculo Liso/efectos de los fármacos , betaendorfina/farmacología , Anafilaxia/inmunología , Animales , Epitelio/fisiología , Cobayas , Histamina/farmacología , Técnicas In Vitro , Masculino , Contracción Muscular/efectos de los fármacos , Naloxona/farmacología , Ovalbúmina/inmunología , Fragmentos de Péptidos/farmacología , SRS-A/farmacología , Tráquea/efectos de los fármacos , Tráquea/inmunología , Tráquea/fisiologíaRESUMEN
It has been shown that opioid peptides induce histamine release and enhance antigen-induced histamine release from isolated peritoneal mast cells. Little is known about the effect of opioid peptides on mast cells present in airway smooth muscle. In the present study, the effect of beta-endorphin on antigen-induced contractions of isolated tracheal rings from actively sensitized guinea pigs was studied. It appears that beta-endorphin has a bidirectional effect on anaphylactic contractions of the trachea. Low concentrations of beta-endorphin (0.1 and 10 nM) significantly potentiate the anaphylactic contractions of tracheal rings. In contrast, higher concentrations of beta-endorphin (0.1 and 1 microM) significantly suppress the anaphylactic contractions of guinea pig trachea. In the presence of the non-selective opioid receptor antagonist naloxone, 10 nM of beta-endorphin still potentiates the anaphylactic contractions of the trachea. This demonstrates that the potentiation of anaphylactic contractions of guinea pig trachea by low concentrations of beta-endorphin is not mediated by opioid receptors. We speculate that the potentiation of the anaphylactic contraction by beta-endorphin is due to an interaction with mast cells.
Asunto(s)
Anafilaxia/fisiopatología , Músculo Liso/efectos de los fármacos , betaendorfina/farmacología , Animales , Cobayas , Técnicas In Vitro , Masculino , Mastocitos/efectos de los fármacos , Mastocitos/metabolismo , Contracción Muscular/efectos de los fármacos , Naloxona/farmacología , Ovalbúmina/inmunología , Tráquea/efectos de los fármacos , Tráquea/fisiopatologíaRESUMEN
Changes of pharmacokinetics of rifampicin (RFP, Rifadin were investigated on endotoxin pretreated still not ruminant calves. The animals served as their own controls and drug administration twice in a 1-week interval gave the same results. Endotoxin 0.02 micrograms kg-1 given intravenously 1 h prior to the oral administration of RFP (20 mg kg-1) induced considerable pharmacokinetic changes. The serum levels of the total drug were significantly lower after the endotoxin administration. The pharmacokinetic analysis revealed significant changes mainly in the distribution phase. When both toxin and drug were administered intravenously, the drug levels were higher. The results are discussed with reference to the pathophysiological endotoxin changes. After the toxin administration the bioavailability of oral RFP was 4-fold lower.
Asunto(s)
Pirógenos/farmacología , Rifampin/metabolismo , Administración Oral , Animales , Temperatura Corporal/efectos de los fármacos , Bovinos , Endotoxinas/farmacología , Inyecciones Intravenosas , Cinética , Lipopolisacáridos/farmacología , Masculino , Rifampin/administración & dosificación , Rifampin/sangreAsunto(s)
Enfermedades de los Bovinos/prevención & control , Ergolinas/farmacología , Ergolinas/uso terapéutico , Hipersensibilidad Tardía , Lisurida/farmacología , Lisurida/uso terapéutico , Metipranolol/farmacología , Propanolaminas/farmacología , Enfermedades Respiratorias/veterinaria , Estrés Fisiológico/inmunología , Animales , Ceguera , Bovinos , Recuento de Leucocitos , Lisurida/análogos & derivados , Ratones , Tamaño de los Órganos/efectos de los fármacos , Enfermedades Respiratorias/prevención & control , Bazo/efectos de los fármacos , Timo/efectos de los fármacos , VibraciónRESUMEN
Trimethoprim (TMP) 10 mg.kg-1 was given orally to calves and rabbits. Two to three weeks later the animals were pretreated by i.v. Peptidoglycan (Pt) 20 micrograms.kg-1. One hour later TMP was administered as above. To other animals under otherwise identical conditions TMP was injected intravenously. The pretreatment with Peptidoglycan induced in both species a significant increase of TMP serum levels positively correlated with temperature elevation. Peptidoglycan pretreatment increased the bioavailability of TMP.
Asunto(s)
Fiebre/sangre , Peptidoglicano/farmacología , Trimetoprim/sangre , Administración Oral , Animales , Disponibilidad Biológica , Bovinos , Femenino , Fiebre/inducido químicamente , Inyecciones Intravenosas , Cinética , Masculino , Conejos , Trimetoprim/administración & dosificaciónRESUMEN
Preruminant calves excreted coccidia oocysts in their faeces after 3 weeks of group housing. Two weeks of oral sulphadimidine (SDM) administration, 50 mg/kg on the first day of treatment followed by daily administration of 37.5 mg/kg, under the same housing conditions kept the faeces free of oocysts. Three weeks later, these calves excreted oocysts again. Repetition of the same treatment for 2 weeks controlled the infection again, but a second treatment for 5 days did not suffice. The repeated long treatment affected immunoglobulin levels adversely. SDM given repeatedly at a lower dose rate (30 mg/kg) for 1-week periods with medication-free intervals of 1 week controlled the infection and no adverse effects were noted. In comparison with controls, weight gains were greater in treated calves.
Asunto(s)
Enfermedades de los Bovinos/tratamiento farmacológico , Coccidiosis/veterinaria , Sulfametazina/uso terapéutico , Animales , Bovinos , Coccidiosis/tratamiento farmacológico , Coccidiosis/parasitología , Esquema de Medicación/veterinaria , Heces/parasitología , Inmunoglobulinas/metabolismo , Sulfametazina/administración & dosificaciónRESUMEN
Changes of pharmacokinetics of rifampicin (20 mg . kg-1 orally) were seen in rabbits pretreated with 0.02, 0.2 and 2.0 micrograms . kg-1 of endotoxin S. typhimurium given intravenously. The animals served as their own controls. The two higher endotoxin doses induced significantly lower plasma levels and changes in the absorption and elimination phase. After the lowest endotoxin dose the results were variable. Tolerance to pyrogenicity of endotoxin, produced by daily toxin administration abolished the otherwise induced changes in rifampicin pharmacokinetics.
Asunto(s)
Endotoxinas/farmacología , Rifampin/metabolismo , Animales , Bovinos , Diarrea/inducido químicamente , Diarrea/metabolismo , Endotoxinas/toxicidad , Fiebre/inducido químicamente , Fiebre/metabolismo , Absorción Intestinal/efectos de los fármacos , Cinética , Masculino , Conejos , Salmonella typhimurium , Especificidad de la EspecieRESUMEN
In farms with large numbers of individually-housed calves, the spread of coccidia is slow. In group pens, however, all the calves became infected within 3-4 weeks of being housed together. At the beginning of group housing no oocysts were found in the faeces of any of the calves. Sulphadimidine (SDM) was administered for 3 or 12 days at different doses and different times. Administration of the drug on Days 3-5 of group housing had no effect. Given between Days 11 and 13 or 17-19, the drug lowered (for a short period) the number of animals found to be excreting oocysts. SDM given between Days 6 and 17 kept the animals oocyst-free during that period. Within 2-3 weeks after the treatment all animals were excreting oocysts.