Subcutaneous tissue and in perimysium internum 12 h just after the injection. These benefits 491 6 cathepsin Inhibitors Related Products suggested that Apoptolidin site betatoxin possessed two eects, indicating that the toxin induced early oedema formation and late necrosis in skin. The toxininduced extravasation was lowered by coinjection with diphenhydramine, a histamine 1 receptor antagonist (Simons et al., 2001; Ishida et al., 2000) (0.1 mg site71, P50.01; 0.5 mg site71, P50.001) inside a dosedependent manner, but was not completely diminished (Figure three). The plasma extravasation induced by histamine was signi antly reduced by coinjection of diphenhydramine (Figure 3). It hence is likely that the toxininduced plasma leakage is completely related to histamine release. To analyse the eect of the toxin on mast cells, mouse mastocytoma P815 cells (56108) have been treated together with the toxin (300 mg ml71) or compound 48/80 (50 mg ml71) for 30 min, and also the histamine within the supernatant was measured. The percentage of histamine release inside the cells was as follows: PBS (vehicle), four.51.8 ; betatoxin, five.12.2 ; compound 48/80, 72.56.8 (means.e.imply,Figure 1 Regional plasma extravasation induced by betatoxin in mouse dorsal skin. (A) Dosedependence of betatoxininduced plasma extravasation. A mixture of 125IBSA and Evans blue dye (0.1 ml of 2.5 resolution) was injected into the tail vein. Right after five min, the betatoxin (five one hundred ng) was injected i.d. (50 ml site71). Plasma extravasation was measured 60 min after the injection of betatoxin. (B) Timecourse of betatoxininduced plasma extravasation. A mixture of 125IBSA and Evans blue dye (0.1 ml of 2.five remedy) was injected inside the tail vein. Following five min, the betatoxin (20 ng site71) was injected i.d. (50 ml site71). Plasma extravasation was measured different time immediately after the injection of betatoxin. Values are the implies.e.imply, n=6.n=5; P50.01, compared with automobile). The outcome indicated that betatoxin can’t induce the release of histamine from the cells. Our prior report also showed that the toxin does not induce the release of histamine from rat mast cells (Sakurai Fujii, 1987). It as a result appears that the toxin will not directly act on mast cells.The impact of tachykinin receptor antagonist and capsaicin on the toxininduced plasma extravasationTo test in the event the toxininduced plasma extravasation is related to tachykinins, the eect of tachykinin NK1 antagonist, [DPro2, DTrp7,9]SP, [DPro4, DTrp7,9]SP and spantide on the toxininduced plasma leakage was investigated. Figure 4 shows that coinjection of these NK1 antagonists resulted inside a reduction in the toxininduced leakage within a dosedependent manner (5.0 10 mg site71). Intradermal injection of a selective NK1 receptor agonist, septide (1.0 nmol site71), induced plasma extravasation in a doserelated manner. The extravasation induced by septide was signi antly decreased by coinjection of NK1 antagonists (Figure 4). [DPro4, DTrp7,9]SP, an NK1 antagonist, exhibited exactly the same potency in inhibiting the toxin or septideinduced plasma leakage (data not shown).British Journal of Pharmacology vol 138 (1)M. Nagahama et alC. perfringens betatoxin and plasma extravasationFigure two Eect of betatoxin on mouse dermal tissue. Saline (A) or betatoxin (50 ng site71) (B) was injected i.d. into the dorsal skin of mice. Right after 12 h, dermal tissues from the dorsal skin have been ed in formalin and sections had been stained with haematoxylin and eosin.Figure three Eect of diphenhydramine on plasma extravasation induced by betatoxin or histamine in dorsal skin of mice. A m.