Evidence for activation of the tissue kallikrein-kinin system in nociceptive transmission and inflammatory responses of mice using a specific enzyme inhibitor

1 The pharmacological activity of phenylacetyl-Phe-Ser-Arg-N-(2,4-dinitroph enyl)-ethylenediamine (TKI), a tissue kallikrein specific inhibitor, was as sessed using models of nociception and inflammation in mice. 2 Injection of TKI (13.6-136 mu mol kg(-1), i.p. or 41-410 mu mol kg(-1), s .c.) produced a dose-related inhibition of the acetic acid-induced writhes (by 37 to 85% or 34 to 80%, respectively). The antinociceptive activity of TKI (41 mu mol kg(-1), i.p.) was maximal after 30 min injection and lasted for 120 min. The effect was unaltered by pretreatment with naloxone (8.2 mu mol kg(-1), s.c.) or bilateral adrenalectomy. 3 TRI (41 and 136 mu mol kg(-1), i.p.) produced a dose-related decrease of the late phase of formalin-induced nociception by 79 and 98%, respectively. At 136 mu mol kg(-1), i.p., TKI also shortened the duration of paw licking in the early phase by 69%. TKI (41 and 136 mu mol kg(-1), i.p.) also reduc ed the capsaicin-induced nociceptive response (by 51 to 79%). 4 TKI (41 pmol kg(-1), i.p. or 410 mu mol kg(-1), s.c.) reduced the oedemat ogenic response, from the second to the fifth hour after carrageenin inject ion by 36 to 30% or by 47 to 39%, respectively. 5 Pretreatment with TKI (41 mu mol kg(-1), i.p.) reduced the capsaicin-indu ced neurogenic inflammation in the mouse ear by 54%. 6 It is concluded that TKI presents antinociceptive and antiinflammatory ac tivities mediated by inhibition of kinin formation by tissue kallikrein in mice. The results also indicate that the tissue kallikrein-dependent pathwa y contributes to kinin generation in nociceptive and inflammatory processes in mice.