Bioassay of histamine.

The usually accepted mothods for bioassay of histamine according to Schild el at. (1951), employ (i) eat's blood pressure, (ii) guinea pig's uterus or (iii) the guinea pig's ileum. Code (1952) has reported that the most convenient tissue for the bioassay of histamine is guinea pig's terminal portion of the ileum and on this account it is the most widely employed pharmacological preparation for the work. In this laboratory also for the above reason, guinea 'pig's ileum was employed for the bioassay of histamine but the tissue was found not reliable as its sensitivity changed with repeated small doses of histamine. This obvious fallacy was more pronounced with locally obtained spotted guinea pig's ileum. This led us to think for some other tissue for the work. Guinea pig's uterus was also not preferred as the spontaneous rhythmic contractions rendered correct interpretation of the results difficult and cats B. P. method was not employed due to non-availability of the animal. Guinea pig's tracheal chain was then employed for the purpose and the present communication is the result of these experiments. These preparations were further employed for testing the blood histamine in 25 normal human subjects.