RESUMEN
1. Norepinephrine (NE) and clonidine produce a phasic, dose-dependent contraction of the isolated guinea-pig terminal ileum. 2. The effect of NE was blocked by prazosin which produced a parallel rightward shift of the concentration-effect curve to NE, with a significant depression of maximum effects. 3. Yohimbine and indomethacin noncompetitively blocked, whereas practolol potentiated, the contractile effect of NE. 4. The contractile effect of clonidine was not antagonized by indomethacin or atropine. 5. These results suggest that the isolated guinea-pig terminal ileum has excitatory receptors sensitive to clonidine stimulation and excitatory alpha receptors sensitive to blockade by prazosin, and that the activation of the latter may be related to the activation of endogenous prostaglandin synthesis.
Asunto(s)
Clonidina/farmacología , Íleon/efectos de los fármacos , Músculo Liso/efectos de los fármacos , Norepinefrina/farmacología , Animales , Atropina/farmacología , Cobayas , Técnicas In Vitro , Indometacina/farmacología , Masculino , Contracción Muscular/efectos de los fármacos , Practolol/farmacología , Prazosina/farmacología , Yohimbina/farmacologíaRESUMEN
Os autores fazem uma revisäo da literatura quanto as manifestaçöes reumáticas induzidas por drogas. Salientam e questionam alguns dos mecanismos envolvidos nas reaçöes adversas as drogas e sua manifestaçöes clínico-laboratoriais, dando enfase ao lúpus-símile. Além disso, alertam sobre a importância em se detectar iatrogenia no curso de uma terapêutica medicamentosa
Asunto(s)
Humanos , Anticonvulsivantes/efectos adversos , Captopril/efectos adversos , Clorpromazina/efectos adversos , Anticonceptivos Orales/efectos adversos , Griseofulvina/efectos adversos , Hidralazina/efectos adversos , Isoniazida/efectos adversos , Penicilamina/efectos adversos , Penicilinas/efectos adversos , Practolol/efectos adversos , Procainamida/efectos adversos , Enfermedades Reumáticas/inducido químicamenteRESUMEN
The influence of the central adrenergic system on basal prolactin secretion was investigated in the rat. Several selective adrenoceptor blockers were centrally administered and their effects on prolactin secretion were observed. Blockade of beta-1 receptors by practolol, beta-2 receptors by IPS 339 and alpha-2 receptors by DG-5128 did not modify basal prolactin secretion, but alpha-1 adrenoceptor blockade by prazosin strongly enhanced prolactin plasma levels. These findings suggest that noradrenergic pathways in the central nervous system exert inhibitory tone on basal prolactin secretion, and that this effect seems to be mediated by alpha-1 adrenoceptors.
Asunto(s)
Prolactina/sangre , Receptores Adrenérgicos/fisiología , Antagonistas Adrenérgicos beta/farmacología , Animales , Hipoglucemiantes/farmacología , Imidazoles/farmacología , Masculino , Practolol/farmacología , Prazosina/farmacología , Prolactina/fisiología , Propanolaminas/farmacología , Ratas , Ratas Endogámicas , Receptores Adrenérgicos/efectos de los fármacosRESUMEN
Effects of practolol on the ATPase activity and mitochondrial membrane potential were studied. The drug enhanced the ATPase activity on undamagedmitochondria and showed very little effect on broken mitochondria. No effect was observed on the ATPase activity by F1-isolated. Practolol gives rise to a decrease in the membrane potential upon energization of the mitochondrial membrane. It is possible that the mechanism of action of practolol could be related with alterations of in permeability (Na+, K+, or Ca2+)
Asunto(s)
Adenosina Trifosfatasas/metabolismo , Mitocondrias/metabolismo , Practolol/metabolismoRESUMEN
In this work we studied the incidence and characteristics of early postinfarction arrhythmias in rabbits with sympathetic denervation. The electrical and haemodynamic changes were analyzed. Three groups of animals submitted to coronary occlusion were studied. A control group of normal animals (I), another group of animals injected with practolol prior to occlusion (5 mg/kg i.v.) (II) and a third group of animals in which stellate ganglia were surgically excised prior to occlusion (III). In the control group incidence of early postinfarction arrhythmias was 60% (12 of 20) while in Groups II and III incidence was only 25% (3 of 12 rabbits). The influence of excision or pharmacological blockade of sympathetic system and their role in the genesis of the early arrhythmias is discussed.