ROLE OF NITRIC-OXIDE, PROSTAGLANDINS AND TYROSINE KINASE IN VASCULAR ENDOTHELIAL GROWTH FACTOR-INDUCED INCREASE IN VASCULAR-PERMEABILITY INMOUSE SKIN

We investigated role of nitric oxide (NO), prostaglandins (PG) and tyr osine kinase in vascular endothelial growth factor (VEGF)-induced incr ease in vascular permeability in mouse skin. Subcutaneous injection of VEGF (0.5-2.0 ng/site) induced dose-and time-dependent increase in va scular permeability at the injection site determined by a leakage of P ontamine sky blue. VEGF (1 ng/site)-induced dye leakage was partially inhibited by NG-nitro-L-arginine methyl ester (an inhibitor for both c onstitutive and inducible NO synthase) (5 and 10 mg/kg, i.v.) and by a minoguanidine (a selective inducible NO synthase inhibitor) (5-20 mg/k g, i.v.), but not by an inactive enantiomer, N-G-nitro-D-arginine meth yl ester (10 mg/kg, i.v.). Pretreatment with an intraperitoneal inject ion of indomethacin (a nonselective cyclooxygenase inhibitor) (5 mg/kg ) or N-(2-cyclohexyloxy-4-nitrophenyl) methanesulphonamide (a cyclooxy genase-2 selective inhibitor) (1-100 mu g/kg) almost completely inhibi ted the effect of VEGF (1 ng/site). Coadministration of PGE(2) (3 and 30 nmol/site) with VEGF did not restore the inhibitory effect of indom ethacin on VEGF (1 ng/site)-induced increase in vascular permeability. Lavendustin A (a selective tyrosine kinase inhibitor) (10 and 50 mu g /kg, s.c.) dose-relatedly inhibited the VEGF (1 ng/site)-induced incre ase in dye leakage, whereas its negative control, lavendustin B (10 mu g/kg, s.c.) had no effect. Another tyrosine kinase inhibitor, geniste in (2.5 mg/kg, s.c.) also inhibited the response. Cycloheximide (a pro tein biosynthesis inhibitor) (35 mg/kg, s.c.) suppressed the response of VEGF (1 ng/site). Histologically, no cellular infiltration was obse rved in the area of VEGF injection. These results suggest that increas ed vascular permeability induced by VEGF is mediated by local producti on of NO and arachidonic acid metabolites other than PGE(2), which are most probably produced by inducible NO synthase and cyclooxygenase-2, respectively. Protein tyrosine kinase-mediated phosphorylation and sy nthesis of any new proteins are likely to be required in this effect o f VEGF in mouse skin.