Abstract
Marked histamine reactions may be demonstrated by perfusion methods in isolated canine organs. The following are the reactions thus far studied:
1. Isolated hind-quarters. Distinct decrease in perfusion resistance (vaso-dilation), increasing the rate of perfusion flow from 15 per cent. to 200 per cent, depending upon the initial vascular tone of the parts. At the height of the reaction, the perfusion rate is identical with the perfusion rate with amyl nitrite. Marked edema of the hind quarters, especially of the genitalia.
2. Isolated intestines. Distinct increase in perfusion resistance (vaso-constriction), decreasing the perfusion rate from 15 per cent. to 50 per cent., depending upon the histamine concentration used. Marked peristaltic movements during the first three minutes of the test, followed by edema, peritoneal transudation, and increased volume of intestinal contents.
3. Isolated liver. Marked increase in perfusion resistance (vaso-constriction), decreasing the perfusion rate as much as 90 per cent. with large histamine doses (1:25000). Edema, peritoneal transudation.
4. Isolated lungs. Marked increase in perfusion resistance (vaso-constriction), decreasing the perfusion rate from 50 per cent. to 75 per cent. depending upon the histamine concentration used. Marked pulmonary edema.
Histological study of these reactions will be reported later.
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