title: [Almitrine bismesylate and ventilation-perfusion ratios].
abstract: Almitrine bismesilate (Vectarion) is characterised by its specific activity on carotid and aortic chemoreceptors. A simultaneous study of the ventilatory and blood gas changes in the anaesthetised dog has shown a dissociation between these two effects. At a dose of 10 to 30 micrograms/kg IV Almitrine bismesilate induces a significant rise in the PaO2 whereas no change in the ventilatory output is observed. A significant transitory rise in the pulmonary arterial pressure also appears at these doses. The juxta position of these results suggests that a feeble doses Almitrine bismesilate improves the blood gases of the arterial blood by a re-distribution of the pulmonary blood flow. Clinical pharmacological studies carried out in bronchitic patients have shown an improvement in the distribution of ventilation perfusion ratios VA/Q by Almitrine bismesilate. These experiments were carried out in animals in order to determine whether the drug had a preferential action on one or other side of the VA/Q ratio. Whereas in an animal with intact lungs, Almitrine bismesilate potentiates hypoxia induced vaso-constriction, in animals whose lungs are ventilated in a heterozygous fashion in such a way as to reproduce zones with a shunt effect, the potentiation of hypoxic vasoconstriction was not again found. At low doses in the hypoxic rat Almitrine bismesilate increases alveolar ventilation (VH) by a significant rise in tidal volume and inspiratory output (VT/TI) without increasing external ventilation. Overall the rise of PaO2 induced by Almitrine bismesilate at low doses may be accompanied by a similar effect on the pulmonary circulation noted in the anaesthetised dog. In the hypoxic rat, it is changes in the alveolar ventilation that are observed.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.forename: Y
authors.initials: Y
authors.lastname: Evrard
mesh_terms: D015765:Almitrine; D000818:Animals; D001991:Bronchitis / Q000503:physiopathology; D002415:Cats; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D002628:Chemoreceptor Cells / Q000187:drug effects; D004285:Dogs; D010879:Piperazines / Q000494:pharmacology*; D011652:Pulmonary Circulation / Q000187:drug effects; D011659:Pulmonary Gas Exchange / Q000187:drug effects; D011817:Rabbits; D051381:Rats; D014692:Ventilation-Perfusion Ratio / Q000187:drug effects*
chemical_list: D000697:Central Nervous System Stimulants; D010879:Piperazines; D015765:Almitrine
vernacular_title: Bismésilate d'almitrine et rapports ventilation-perfusion.