[Activity of almitrine bismesylate on pulmonary hemodynamics and on the liberation of prostanoids in the lymph nodes in sheep].

Almitrine Bismesylate (0.25 mg X kg-1) was perfused for 10 minutes into the pulmonary artery of 4 sheep (40 kg) which were anaesthetized, paralysed and ventilated with 50% oxygen in air and prepared according to Staub et al (J. Surg. Res. 19:315, 1975). The preparation was followed for 2 hours baseline and for four hours after perfusion and comparisons made using analysis of variance. We noted a transitory phase marked by a peak of pulmonary vascular resistance (PVR) at 25 +/- 15 minutes due to a rise in mean pulmonary artery pressure PAP from 14 +/- 2 to 23 +/- 5 cm H2O. PO2 fell from 220 +/- 40 to 180 +/- 25 Torr. A stable haemodynamic state was attained after 90 minutes. PAP was slightly above control and PaO2 significantly elevated (230 +/- 30 Torr P less than 0.05). Left atrial pressure, PCO2, pH, and lung lymph flow did not change. The mild stable vasoconstriction associated to a rise in PaO2 at constant ventilation and high PaO2 does not suggest a straightforward role for chemoreceptors. It is compatible with redistribution of VA/Q ratios by local mediators. Lung lymph was assayed for prostanoids using radio immunological methods. A significant rise in 6 keto PGF1 alpha immunoreactivity was found posterior to the haemodynamic peak. HPLC is required to quantify further this rise.