Histamine in Rat Plasma; Correlation with Blood Pressure Changes Following X-irradiation

Abstract

Rats receiving a mid-lethal dosage of X-irradiation (600 r) showed assayable histamine in concn. of 1 to 2 [mu]g./2 cc. of blood plasma at 2-hr. and 5-day intervals following the irradiation. The periods of increased histamine concn. correlated with a marked fall in blood pressure and strongly suggest that histamine is released by radiation and is responsible for the lowered blood pressure. 50% of the rats did not recover from the histamine rise in the plasma on the 5th day and died in a state of shock on the 9th or 10th days after irradiation.