Implication of a Nitric Oxide Synthase Mechanism in the Action of Substance P: L‐NAME Blocks Thermal Hyperalgesia Induced by Endogenous and Exogenous Substance P in the Rat

The effects of i.p. administration of the nitric oxide synthase inhibitor NG-nitro-L-arginine methylester (L-NAME) and its inactive isomer, D-NAME, were tested in two nociceptive paradigms in the rat. In the first paradigm, rats were lightly anaesthetized with a mixture of chloral hydrate (120 mg/kg, i.p.) and sodium pentobarbital (20 mg/kg, i.p.). Tail flick reaction times were monitored and thermal hyperalgesia was induced by immersion of the …