The effect of hypoxia on the number of amine-containing cells in the lung of the adult rat.

Adult rats of Wistar and Sprague Dawley strains were exposed to a 21-day period of hypoxia (10% O2). At the end of this period, the hypoxic animals and paired controls were anaesthetised, dissected and tissues were taken for light microscopy. All the hypoxic animals had an increased haematocrit, right ventricle weight and carotid body size when compared with controls. The Grimelius method was used to demonstrate argyrophil structures in the lung. This method stained the amine-containing cells of the epithelium, mast cells and nerves. Mast cells associated with the pulmonary vasculature were increased in number in the hypoxic animals. Single epithelial argyrophil cells were more frequent than those in groups. In control animals the groups of cells only rarely contained more than 5 cells. In the Wistar strain there was no significant difference in the number of argyrophil cells between the control animals and those exposed to chronic hypoxia. However, in the Sprague Dawley rats, the numbers of cells, both single and in groups, were significantly increased following 3 weeks chronic hypoxia. The cell groups were also larger in the hypoxic animals, with up to 12 cells per section.