Camelo JS, Hehre D, Devia C, Camelo SHH, Bancalari E, Suguihara C. The role of angiotensin II receptor-1 blockade in the hypoxic pulmonary vasoconstriction response in newborn piglets.
Neonatology 2008;
93:263-8. [PMID:
18043007 DOI:
10.1159/000111879]
[Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Accepted: 09/14/2007] [Indexed: 11/19/2022]
Abstract
BACKGROUND
Angiotensin-converting enzyme activity is increased in newborn infants with respiratory distress syndrome and in animals with alveolar hypoxia.
OBJECTIVE
To test whether angiotensin II (Ang II) mediates the pulmonary vasoconstriction induced by acute hypoxia in newborn piglets.
METHODS
Eight unanesthetized chronically instrumented newborn piglets (mean +/- SEM; age 6.6 +/- 0.6 days; weight 2,181 +/- 174 g) were randomly assigned to receive a saline solution or the Ang II type 1 receptor (AT(1)) antagonist, losartan, in a crossover study design, with an interval of at least 48 h between the first and second study. Pulmonary artery (Ppa), wedge, systemic arterial (Psa) and right atrial pressures, cardiac output (CO), pulmonary (PVR) and systemic (SVR) vascular resistances, and arterial blood gases were obtained in room air, before and during the saline or losartan infusion (6 mg/kg followed by 3 mg/kg/h), and during 6 h of hypoxia (FiO(2) = 0.11) and saline or losartan infusion. Data were analyzed by repeated measures analysis of variance.
RESULTS
The pulmonary vasoconstriction induced by acute hypoxia was significantly attenuated during losartan infusion, while Psa, SVR, CO, pH, PaCO(2), PaO(2) and base excess did not differ between groups. During room air, Ppa, PVR, Psa, SVR and CO values were not modified by saline or losartan infusion.
CONCLUSION
These data suggest that the pulmonary vasoconstriction induced by acute hypoxia in newborn piglets is partially mediated by Ang II, acting via AT(1).
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