N(2)O stimulates NOS enzyme activity in C57BL/6 but not DBA/2 mice.

Exposure to 70% N(2)O produces a prominent antinociception in C57BL/6 mice but not DBA/2 mice. N(2)O exposure also increases conversion of [14C]L-arginine to [14C]L-citrulline in homogenates prepared from whole brains of C57BL/6 mice; there was no such increase in NOS activity in the DBA/2 whole brain. A differential N(2)O effect on brain NOS in these inbred strains might explain why the C57BL/6 but not DBA/2 mice are responsive to N(2)O antinociception.