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Vasodilatory effect of aerosol histamine during pulmonary vasoconstriction in unanesthetized sheep
Author(s) -
Stecenko Arlene A.,
Lefferts Peter L.,
Mitchell John A.,
Snapper James R.,
Brigham Kenneth L.
Publication year - 1987
Publication title -
pediatric pulmonology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.866
H-Index - 106
eISSN - 1099-0496
pISSN - 8755-6863
DOI - 10.1002/ppul.1950030211
Subject(s) - medicine , vasoconstriction , vasodilation , hypoxic pulmonary vasoconstriction , histamine , anesthesia , cardiology
The effects of aerosol histamine on pulmonary vascular resistance during pulmonary vasoconstriction were studied in 12 unanesthetized sheep. Sheep were chronically instrumented with Silastic catheters in the pulmonary artery and left atrium, thermodilution Swan‐Ganz catheter in the main pulmonary artery for measurement of cardiac output, and tracheostomy for delivery of hypoxic gas and/or aerosol histamine. Seven minutes of isocapnic hypoxia (Fl O2 = 0.12) caused pulmonary artery pressure (P PA ) to increase from 17.2 ± 0.4 to 27.0 ± 1.0 cm H 2 O (X¯ ± SEM, P < 0.05) and pulmonary vascular resistance (PVR) to increase from 3.94 ± 0.33 to 4.71 ± 0.38 cm H 2 O · L −1 . min (P < 0.05). When sheep breathed a combination of aerosol histamine (5 mg/ml) and 12% O 2 , P PA rose only to 21.3 ± 1.11 cm H 2 O and PVR decreased to 3.51 ± 0.31 cm H 2 O · L −1 . min. This was a significantly (P < 0.05) smaller response compared to hypoxia alone. Aerosol histamine alone had no significant effect on P PA or PVR. Meclofenamate did not restore the histamine‐induced loss of hypoxic vasoconstriction. Aerosol histamine significantly blunted the pulmonary vasoconstriction caused by intravenous serotonin (8 μg/kg/min) and intravenous prostaglandin H 2 ‐analog (0.74 μg/kg/min). It was concluded that in the awake sheep aerosol histamine acted as a pulmonary vasodilator only in the presence of pulmonary vasoconstriction. Pediatr Pulmonol 1987; 3:94–100 .