NOCICEPTIVE RESPONSES OF GUINEA-PIGS TO INTRADERMAL INJECTIONS OF BRADYKININ AND KALLIDIN-10.

Nine behavioural responses were observed to follow with reasonable frequency intradermal injection into guinea-pigs of strongly anisotonic solutions, which are known to cause pain in human skin. These responses were recorded on a form, and a procedure was devised for obtaining a nociceptive score from the records. Intradermal injection of bradykinin or kallidin-10 gave a response pattern indistinguishable from that to a strongly anisotonic solution. Each kinin raised the nociceptive score in response to the control solutions, as also did acetylcholine and histamine; but 5-hydroxytryptamine and pH changes within the range of 3.1 to 10.3 did not significantly raise the control score. The effect of bradykinin was depressed by subcutaneous injection of morphine or codeine, but was unaffected by amidopyrine, calcium acetylsalicylate, chlorpromazine or phenylbutazone.