A fluometric determination of histamine upon the administration of macrolide antibiotics.

The intravenous injection of the macrolide antibiotics such as spiramycin (30 mg/kg), oleandomycin (50 mg/kg), and erythromycin (30 mg/kg) in cats and dogs resulted in marked declines of blood pressure in our previous experiments1). The mechanism of action was shown to be due to the in vivo release of histamine (H) by a biological method. Of the methods of bioassay for H, cat blood pressure2) and isolated guinea pig intestine3) have been utilized. These methods are subject to spontaneous errors. The influence of individual and sexual differences of animals, as well as skill in the experimental technic is recognized. As a consequence, many experiments are required and the results have to be analyzed statistically. According to YAMADA4) in the current concept of the presence of H releasers, the biological assay requires both the blood pressure method and the guinea-pig intestine method. In the present study H in the blood was determined chemically and by bioassay at the time of the blood pressure fall following the administration of macrolide antibiotics.