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Nitric oxide further attenuates pulmonary hypertension in magnesium‐treated piglets
Author(s) -
Haas Kelly Mullins,
Suzuki Satoshi,
Yamaguchi Nobuyuki,
Kato Ineko,
Ban Kyoko,
Tanaka Taihei,
Fukuda Sumio,
Togari Hajime
Publication year - 2002
Publication title -
pediatrics international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.49
H-Index - 63
eISSN - 1442-200X
pISSN - 1328-8067
DOI - 10.1046/j.1442-200x.2002.01632.x
Subject(s) - medicine , pulmonary hypertension , nitric oxide , hypoxia (environmental) , pulmonary artery , magnesium , contraction (grammar) , anesthesia , respiratory system , cardiology , oxygen , chemistry , organic chemistry
Background: Persistent pulmonary hypertension of the newborn (PPHN) commonly appears as a complication of several pulmonary and non‐pulmonary diseases. The hypoxia possibly inhibits Ca 2+ ± dependent K + channels, thus resulting in membrane depolarization of pulmonary smooth muscle cells, which leads to the opening of Ca 2+ channels and Ca 2+ entry, resulting in contraction of the vascular smooth muscle. However, magnesium (Mg 2+ ) is an antagonist of Ca 2+ . We studied the effect of magnesium sulfate on the treatment of hypoxia‐induced pulmonary hypertension and compared to the site of action of nitric oxide (NO).Methods: Zero‐day‐old piglets were used in each experiment. The effects of Mg 2+ were tested in each hypoxic, normoxic and hyperoxic states. Once the desired physical state was achieved, Mg 2+ was administered at a dose of 100 mg/kg approximately every 10 min. In order to determine the exact mechanism of the Mg 2+ , N w‐nitro‐ l ‐arginine (LNNA), a NO synthase‐inhibitor, was administered simultaneously with Mg 2+ in some of the experiments.Results: There was a significant correlation between the percent reduction of the pulmonary arterial pressure (PAP) caused by magnesium and the level of oxygen (O 2 ) present in the pulmonary artery. The greatest amount of reduction was seen in the hypoxic condition where the least amount of O 2 is found. A further reduction in the PAP was seen when NO was given at the end of the Mg 2+ trials. There was no significant reduction seen in the systemic arterial pressure.Conclusion: Inhaled NO further reduced the PAP in piglets already treated with Mg 2+ .