L-NAME augments the antinociceptive effects of intracerebroventricularly applied ET-1 and ET-3.

The interaction between endothelin-1 (ET-1) (5 pmol/mouse, i.c.v.) and endothelin-3 (ET-3) (5 pmol/mouse, i.c.v.) with NG-nitro-L-arginine methyl ester (L-NAME) (5 mg/kg i.p., 30 min pretreatment) was investigated in mice by the use of two experimental procedures: hot plate and tail flick tests in mice. L-NAME showed slight insignificant antinociceptive action, but augmented significantly the antinociceptive effects of i.c.v. administered ET-1 and ET-3 in both experimental tests.