Abstract

Rats kept in 10% O2 for three or more weeks developed mast cell hyperplasia in the lungs, especially round the alveoli and the small peripheral blood vessels, which became thickened during chronic hypoxia. There was a significant correlation between the degree of right ventricular hypertrophy (RVH) and the numbers of alveolar and small vessel mast cells. However, mast cell hyperplasia developed more slowly than RVH. Daily treatment with disodium cromoglycate failed to prevent RVH in hypoxic conditions but was associated with retardation of growth in both hypoxic and control rats. Neither acute nor chronic hypoxia increased the degree of degranulation in the lung mast cells.