The effect of aspirin on pain and hand blood flow responses to intra‐arterial injection of bradykinin in man

Abstract

A new method of evoking pain by the intra‐arterial injection of bradykinin (into the brachial artery) was used in the evaluation of the analgesic activity of sodium and calcium acetylsalicylate. At the same time, hand blood flows were measured by venous occlusion plethysmography, and the plasma was analyzed for acetyl, free, and protein‐bound salicylate. The analgesic effect of aspirin appears during the second half of the first hour and continues beyond the second hour after drug administration. Bradykinin increases the hand blood flow and there is an apparent increase in flow after aspirin. No correlation could be found between the plasma salicylate level and the state of analgesia.