Evaluation of histamine induced acute inflammation by 67Ga-citrate in conscious rats.

Radioactivity of 67Ga in the paw edema and the edema rate were measured after subcutaneous injection of histamine into the paw of the conscious rat. The radioactivity increased almost parallel with the edema rate following the injection of histamine. The increase in the radioactivity and edema were almost completely prevented by pretreatment with a 10 mg/kg dose of chlorpheniramine, an antihistaminic agent. A good correlation between the edema rate and the radioactivity was demonstrated. These results suggest that 67Ga-citrate is useful for monitoring the process of acute inflammation in the pharmacological evaluation of anti inflammatory drugs. Moreover, there is also a possibility that 67Ga-citrate may be useful in measuring vascular permeability.