[Effect of dopamine in dopaminergic doses on pulmonary circulation of dogs in normoxia and hypoxia]. / Efeitos da dopamina em doses dopaminérgicas sobre a circulação pulmonar de cães em normóxia e hipóxia.

PURPOSE: To study if dopamine in dopaminergic doses (1.5 and 4.0 micrograms/kg/min) had some effect on the pulmonary vasoconstriction mechanism, and if in those doses the drug had some action on systemic and pulmonary hemodynamic variables, as well as in the pulmonary gas exchange. METHODS: Seventeen normal mongrel dogs, anesthetized and paralized under mechanical ventilation were submitted to two different gas mixtures: room air (F1O2 = 0.2093 -10 dogs) and hypoxic mixture (F1O2 = 0.125 -7 dogs). Dopamine was infused in both groups during 15 min in the two doses 1.5 and 4.0 micrograms/km/min, separated by a period of 30 min. RESULTS: Pulmonary hemodynamics and gas exchange variables after infusion of dopamine at 1.5 and 4.0 micrograms/km/min in dogs in normoxia and hypoxia. [table: see text] CONCLUSION: Dopamine in the used doses had no action on the pulmonary circulation and on the hypoxic pulmonary vasoconstriction mechanism; pulmonary gas exchange was not affected by dopamine in both doses during normoxia and hypoxia; in the experimental model there was no evidence of dopaminergic receptors in the pulmonary vessels.