Fj. Dowell et W. Martin, INTERACTION BETWEEN PEROXYNITRITE AND L-CYSTEINE - EFFECTS ON RAT AORTA, European journal of pharmacology, 344(2-3), 1998, pp. 183-190
In rings of rat aorta previously exposed to peroxynitrite (1 mM), L-cy
steine and its analogues containing, but not those lacking, a thiol gr
oup produced a powerful transient relaxation. This relaxation is likel
y to result from the release of nitric oxide from a nitrated/nitrosate
d compound formed following reaction of peroxynitrite. with a componen
t of the tissue or bathing medium. Furthermore, when peroxynitrite was
pre-mixed with L-cysteine a new relaxant species was formed. Analogue
s of L-cysteine with a free thiol reacted with peroxynitrite to form s
pecies with similar relaxant potencies. Analogues lacking a thiol form
ed products with relaxant activity, but less than with L-cysteine. Ana
logues with a free amino but no thiol or carboxylic functions formed p
roducts with potencies similar to those lacking only the thiol. If the
amino is substituted and the thiol removed, no relaxant activity was
generated. Thus, peroxynitrite reacts with L-cysteine to form a novel
relaxant whose activity derives mainly from formation of its S-nitroso
thiol, with a lesser component perhaps from an N-nitroso derivative. (
C) 1998 Elsevier Science B.V.