Hypoxic pulmonary vasoconstriction in conscious sheep. Role of mast cell degranulation

T. Ahmed, W. Oliver, B. L. Frank, M. J. Robinson, A. Wanner

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

We used pharmacologic and histologic techniques to investigate the role of mast cells in the mediation of hypoxic pulmonary vasoconstriction in conscious sheep. Breathing a hypoxic gas mixture (13% O2, 87% nitrogen) caused hypoxic pulmonary vasoconstriction (HPV) with increases in mean pulmonary artery pressure and pulmonary vascular resistance by 97 and 90%, respectively. Intravenous pretreatment with the mast cell membrane stabilizing agent cromolyn sodium (3 mg/kg/min) completely blocked HPV, whereas the H1-histamine receptor antagonist chlorpheniramine, alone or in combination with the H2-receptor antagonist metiamide and the prostaglandin synthetase inhibitor indomethacin, failed to prevent HVP. Cromolyn sodium failed to modify the pulmonary pressor response to infusions of norepinephrine (alpha-agonist), tyramine (catecholamine-releasing agent), and histamine, indicating the specificity of cromolyn sodium action on the mast cells. Electromicroscopic studies of pulmonary perivascular mast cells showed that a 90-min exposure to the hypoxic gas mixture reduced the total number of granules per mast cell to 75% of control. This was blocked by cromolyn sodium pretreatment. We conclude that in conscious sheep, HPV is initiated by the liberation of a mast cell product (other than histamine) that either directly or indirectly causes pulmonary vasoconstriction.

Original languageEnglish (US)
Pages (from-to)291-297
Number of pages7
JournalAmerican Review of Respiratory Disease
Volume126
Issue number2
StatePublished - Oct 25 1982

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine

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