Abstract
1 The relative effects of prostaglandin E1, bradykinin and histamine on canine synovial vascular permeability were investigated by a method based on the measurement of the amounts of radiolabelled dextran (molecular weight 20,000) leaking from the circulation into the synovial cavity. 2 Bradykinin, prostaglandin E1 and histamine in that order of potency all increased synovial vascular permeability. Threshold concentrations were 0.3 micrometer, 3 micrometer and 30 micrometer respectively. 3 The effects of infusion of prostaglandin E1 combined with either bradykinin or histamine were greater than mere summation.