[The role of angiotensin-converting enzyme inhibitor (captopril) on the mechanism of hypoxic pulmonary vasoconstriction. Experimental study in dogs].
In order to evaluate the action of an angiotensin converting enzyme inhibitor (Captopril) on the pulmonary hypoxic vasoconstriction, twenty one mongrel dogs were studied in two groups: group I with hypoxia, group II with normoxia. The dogs were anesthetized, intubated, and had their femoral vein and artery cannulated for blood-gas sampling and pressure records. They were mechanically ventilated with hypoxic gas mixtures (12.3% O2-87.7% N2)--group I and room air group II, at random. In both groups we measured, before and after administration of captopril 3 mg/kg intravenously, gas exchange and hemodynamic variables, as well as plasmatic levels of renin and angiotensin converting enzymes (ACE). Our results showed that the group I dogs decreased the systemic and pulmonary vascular resistances with small changes in pulmonary arterial pressures and no significant variations of pulmonary systemic resistances ratio. There were no significant variations of the same variables in the group II dogs. The gas exchange has not changed in either group of animals. In the group I dogs Captopril provoked systemic and pulmonary vasodilatation, with no gasometric and ventilation/perfusion ratio changes. In our experimental model we could not conclude that Captopril inhibited the hypoxic pulmonary vasoconstriction and/or that the angiotensin II had some action on the hypoxic pulmonary vasoconstriction mechanism, but there are some evidences favoring that hypothesis.
Soares
G P
GP
Romaldini
H
H
dos Santos
M L
ML
Ratto
O R
OR
D000704:Analysis of Variance; D000818:Animals; D002216:Captopril / Q000494:pharmacology*; D004285:Dogs; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D000860:Hypoxia / Q000503:physiopathology*; D008168:Lung / Q000098:blood supply*; D008297:Male; D007703:Peptidyl-Dipeptidase A / Q000097:blood; D012083:Renin / Q000097:blood; D012129:Respiratory Function Tests; D014661:Vasoconstriction / Q000187:drug effects*
D002216:Captopril; D007703:Peptidyl-Dipeptidase A; D012083:Renin
Papel do inibidor da enzima conversora da angiotensina (captopril) no mecanismo da vasoconstricção pulmonar hipóxica. Estudo experimental em cães.