Angiotensin II potentiates methacholine-induced bronchoconstriction in human airway both in vitro and in vivo
| Autor: | Neil C. Thomson, E. A. Millar, Jane E. Nally |
|---|---|
| Rok vydání: | 1995 |
| Předmět: |
Pulmonary and Respiratory Medicine
Adult Male medicine.medical_specialty Bronchoconstriction Bronchi In Vitro Techniques Bronchoconstrictor Agents Double-Blind Method In vivo Internal medicine medicine Humans Methacholine Chloride Asthma Analysis of Variance business.industry Angiotensin II Respiratory disease Drug Synergism Muscle Smooth medicine.disease Pathophysiology Stimulation Chemical Endocrinology Acute severe asthma Methacholine Female medicine.symptom business medicine.drug |
| Zdroj: | The European respiratory journal. 8(11) |
| ISSN: | 0903-1936 |
| Popis: | Angiotensin II levels are elevated in patients with acute severe asthma. In addition, intravenous angiotensin II causes bronchoconstriction in mild asthmatic patients. In the present study, we examined the effects of this hormone on bronchi in vitro and its interaction with the cholinergic agonist methacholine both in vivo and in vitro. Contractions of rings of human bronchi were measured isometrically. Concentration-response curves were obtained to angiotensin II and to methacholine in the presence and absence of angiotensin II. In addition, seven asthmatic patients with mild bronchial hyperreactivity to methacholine received placebo, angiotensin II, 1 or 2 ng.kg-1.min, by infusion, followed by methacholine challenge. Forced expiratory volume in one second (FEV1) values were measured at baseline, at the end of the infusion and during methacholine challenge. Angiotensin II alone in vitro evoked small contractions of human bronchi ( < 0.25 g wt). Pre-incubation with low concentrations of angiotensin II significantly enhanced contractions to methacholine. In mild asthmatic patients, angiotensin II alone evoked no change in baseline FEV1 values at the levels studied. Compared to placebo, angiotensin II 2 ng.kg-1.min, but not 1 ng.kg-1.min, evoked a significant increase in bronchial reactivity to methacholine. Angiotensin II in subthreshold concentrations enhances methacholine-evoked bronchoconstrictions both in human in vitro and in mild asthmatic patients in vivo. Our findings suggest a novel role for angiotensin II as a putative mediator in asthma. |
| Databáze: | OpenAIRE |
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