Abstract

Enhanced serum levels neopterin are associated with various immune-related diseases like septic shock and vascular leakage syndrome. Tetrahydrobiopterin (THB, 100 muM) but not bioterin induces appreciable endothelium-dependent vasodilatation and enhances cGMP-level (95% increase) to the same extent as arecoline. NG-methyl-L-arginine (L-NAME) does not antagonize the tetrahydrobiopterin effects. In addition, tetrahydrobiopterin enhances cGMP-level in tracheal smooth muscle (+28%) and artery pulmonalis (+57%). Present results show that tetrahydrobiopterin being precursor of biopterin and co-factor of NO-synthase, induces vasodilatation by increasing intracellular cyclic GMP level and suggest a prominent role for tetrahydrobiopterin in immune-triggered hypotension.