Lung mast cells and hypoxic pulmonary vasoconstriction in cats

An attempt was made to reduce or eliminate lung mast cells in order to determine the involvement of mast cells in hypoxic pulmonary vasoconstriction. Anesthetized cats were exposed to acute hypoxia (10% O2) 20-24 h after no pretreatment, after total lung irradiation (3,000 r), after intravenous nitrogen mustard, or after combined lung irradiation and nitrogen mustard. None of the treatments reduced total or perivascular lung mast cell density, or reduced the pulmonary vasoconstrictor response to hypoxia. However, an inverse relationship between lung mast cell density and the pulmonary pressor response to hypoxia was observed. These results suggest that the presence of more lung mast cells may oppose hypoxic pulmonary vasoconstriction.