Capsaicin-induced nonneural vasoconstriction in canine mesenteric arteries.

Prolonged cold storage (4 degrees C) of canine mesenteric arteries was used to reveal the role of nonneural mechanisms in capsaicin-induced vascular contraction. The EC(50) values of capsaicin were 3.0 microM, 670 and 104 nM in preparations made fresh, after a 1- or 2-week period of cold storage, respectively, indicating an enhanced contractile responsiveness of the denervated tissue to capsaicin. A similar exaggerated contractile response was seen with phenylephrine exclusively after a 1-week cold storage. For fresh, 1- and 2-week cold-stored arteries, the EC(50) of phenylephrine were 248, 38 and 30 nM, respectively. The maximum contraction produced by tyramine was decreased with time. The results suggest that capsaicin may attain vasoconstriction independent of neural elements.