Abstract

CABEZAS, GA  and  VELASCO, M. Acciones de la Dopamina en las Vías Aéreas. AVFT [online]. 2002, vol.21, n.1, pp.65-73. ISSN 0798-0264.

ABSTRACT Dopamine modulates other processes in peripheral organs in addition to its function on the central nervous system (CNS). In the respiratory system dopamine modulates ventilation through carotid body, and also modulates pulmonary blood vessels, alveolar liquids exchange and possibly participates in the regulation of airways diameter. We have examined the possible modulating effect of dopamine on bronchial diameter by administering inhaled dopamine and the DA2 dopaminergic blocker metoclopramide (MTC) to subjects with various degrees of bronchial tone. Methods: We examined 56 volunteers. Arterial blood pressure and heart rate were determined in every subject. By means of spirometry, we measured forced vital capacity (FVC), forced expiratory volume in the first second (FEV₁), maximal forced expiratory flow (FEF_max) and forced expiratory flow at 50% of vital capacity (FEF₅₀), before and after each treatment. By inhalation with a nebulizer we administered a) dopamine (0.5 mg/kg/min) to 10 healthy subjects, 10 subjects with asthma without acute bronchospasm (AWAB) and 16 subjects with acute asthma attack (AAA); b) Intravenous metoclopramide (7 mg/kg/min) was administered to 10 healthy subjects and 10 subjects with AWAB. For ethical reasons MTC was not used in subjects with acute asthma attack. Statistics: Non parametric Wilcoxon’s test for paired samples, ANOVA test and Bonferroni multiple comparison test were performed. Results: Inhaled dopamine increased FEV₁ and FVC, FEF_max and FEF₅₀ in the AAA group, but there were no modifications in the healthy group nor in the AWAB group. Metoclopramide did not induced changes on respiratory parameters in healthy individuals or those with AWAB. Conclusions: Inhaled dopamine was able to induce bronchodilatation when the bronchial tone is already increased by acute asthma attack but It did not modify the resting bronchial tone in normals or in asthmatics without acute bronchospasm. D2 blockade with metoclopramide did not modify resting bronchial tone either. We suggest dopamine exerts a modulatory effect on bronchial tone of human airways depending on the degree of existing basal tone.

Keywords : Human bronchial tone; Airways; Dopamine; Acute asthma; D2 blockade.