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ACTION OF ALMITRINE BISMESYLATE ON VENTILATION‐PERFUSION MATCHING IN CATS AND DOGS WITH PART OF THE LUNG HYPOVENTILATED
Author(s) -
Wach R. A.,
Gill G. W.,
Suggett A. J.,
Bee D.,
Barer G.
Publication year - 1986
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1986.tb00926.x
Subject(s) - anesthesia , medicine , cats , ventilation (architecture) , hypoxic pulmonary vasoconstriction , perfusion , vasoconstriction , cardiology , mechanical engineering , engineering
SUMMARY 1. Ventilation to one lobe of lung was reduced in anaesthetized open‐chest cats and dogs to simulate the ventilation/perfusion (V̇/Q̇) mismatching of chronic lung disease. Blood flow to this lobe fell less than ventilation; thus lobar V̇/Q̇ diminished. 2. In seven cats almitrine (0.5 mg/kg + 10 μg/kg per min, i.v.) caused a rise in pulmonary artery pressure ( P PA ), increased flow through the hypoventilated lobe in six out of seven cats and both increased or decreased lobar vascular resistance (PVR); the lobar V̇/Q̇ ratio therefore fell. Arterial and lobar venous oxygen tension ( P o 2 ) fell. 3. In five dogs almitrine caused a rise in P PA and PVR but lobar flow changes were variable. Arterial and lobar venous P o 2 fell. 4. With fixed ventilation, almitrine failed to improve V̇/Q̇ matching; there was no improvement in gas exchange in the hypoventilated lobe. 5. In eight dogs the hypoventilated lobe was perfused at constant flow with right atrial blood (i.e. while V̇/Q̇ was held constant). Almitrine caused a rise in perfusion pressure, vasoconstriction, followed, in five out of eight dogs, by vasodilatation. 6. In six similar cat preparations, vasoconstriction but not vasodilatation was clearly shown. In two cats dilatation after almitrine was demonstrated during ventilation with Nitrogen. 7. In all experiments there was no significant effect of the solvent. 8. Thus the dual action of almitrine seen in other species was seen in a proportion of cats and dogs. 9. Results do not support the view that improved arterial gas tensions in patients after almitrine are attributable to diversion of blood flow away from hypoxic lung. Alternative mechanisms are discussed.