Histamine induced cardiovascular lesions

Abstract

1. 1. Data have been presented showing that the intraperitoneal administration of histamine acid phosphate in rabbits, guinea pigs, and rats produces an inflammatory reaction in the vascular system of the lung and the heart and in the endo- and myocardium. 2. 2. Certain lesions are identical both in location and type in all 3 species, such as edema of the endocardium, inflammatory cell collections in the myocardium, edema of the heart valves, perivascular edema, and inflammatory cell exudate about the blood vessels. 3. 3. As between the species, some types of lesion vary, although the location is the same. In the lung, the rabbit shows perivascular inflammatory cell exudate with slight perivascular edema and an occluding proliferation of inflammatory cells within the lumen of both veins and arteries. The rat shows perivascular infiltration with inflammatory cells and some edema. The guinea pig shows a very marked perivascular edema and some perivascular inflammatory cell exudate and in addition, a marked thickening of the muscular coat of the arteries leading to final occlusion of the lumen. There is little or no proliferation within the lumen. The guinea pig additionally presents peribronchial inflammatory reaction. All 3 species show atelectasis of irregular areas in the lung. These various lesions are most intense and extensive in the guinea pig, least so in the rat, with the rabbit in the mid-position. 4. 4. Up to a certain point the extent and intensity of the lesions increase with the amount of histamine administered. Beyond this, additional amounts of histamine do not increase the severity of the reaction. It is apparent that the animals develop a tolerance to histamine.