DURING the treatment of adults for migraine with intravenous injections of histamine,1 it was observed that the qualitative platelet activity was increased. In this earlier study data on 15 patients who received intravenous injections of histamine for migraine were obtained. Blood was drawn before onset of each injection, using the technic of Sanford and Leslie.2 This blood was collected in chilled syringes, counted on a chilled counting chamber and centrifuged in waxed chilled tubes. The coagulation times for whole blood, cell-free plasma and platelet-free plasma were determined. Hematocrit readings and platelet counts were made simultaneously.
The histamine was given at a constant rate of 20 drops per minute in 500 cc. of isotonic sodium chloride solution. The quantity of histamine was doubled with each injection, 0.2 mg. being used for the first injection and 2.0 mg. for the last. The results of these determinations are presented in chart