Topical acetyl salicylate and dipyrone attenuate neurogenic protein extravasation in rat skin in vivo

The effect of topically applied acetyl salicylic acid (ASA) and dipyrone on capsaicin-evoked protein extravasation was investigated by dermal microdia lysis in rat. After a baseline of 75 min, capsaicin (1%) was applied epicut aneously under occlusion for 75 min above the capillaries. Topical capsaici n stimulation induced neurogenic protein extravasation with a mean increase of protein concentration in the perfusate of 165 +/- 27% (mean +/- SEM; n = 15), whereas in sham-stimulated sites protein concentration decreased to 73 +/- 7% of the prestimulation value (n = 6). ASA (2-200 mg/ml) and dipyro ne (3-300 mg/ml) dose-depentently reduced the capsaicin induced protein ext ravasation to 118 +/- 23% (ASA, 200 mg/ml; n = 8) and 72 +/- 9% (dipyrone, 300 mg/ml; n = 8) of the prestimulation value. ASA a nd dipyrone antagonize d the excitatory effects of capsaicin on skin nociceptors and thus suppress ed the neurogenic protein extravasation. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.