Cell lines

Purified brain NOS

Preparation Method

L-NAME hydrochloride was added as 10 fold stock solutions of the respective hydrochlorides freshly prepared in water. For the bioactivation experiments aliquots of 10ul of the buffer,added to 90ul of the NOS reaction mixtures, yielding a theoretial final L-NAME concentration.

Reaction Conditions

0-1mM L-NAME hydrochloride for 24h

Applications

Freshly dissolved L-NAME was a inhibitor of purified brain NOS (mean IC₅₀ = 70 μM), the apparent inhibitory potency of L-NAME approached that of L-NOARG upon prolonged incubation at neutral or alkaline pH.

Animal models

Adult male Wistar rats (70–100 days of age)

Preparation Method

Male Wistar rats were randomly assigned to control (C), L-NAME (L), chronic aerobic exercise (Ex), and chronic aerobic exercise associated to L-NAME (ExL). Aerobic training was performed with progressive intensity for 12 weeks; L-NAME was administered by orogastric gavage.

Dosage form

1.5 mg/kg/day L-NAME, oral gavage

Applications

Low-dose L-NAME alone did not change systolic blood pressure (SBP), but ExL significantly increased SBP at week 8 with normalization after 12 weeks. Furthermore, ExL promoted the elevation of left ventricle (LV) end-diastolic pressure without the presence of cardiac hypertrophy and fibrosis. Time to 50% shortening and relaxation were reduced in ExL, suggesting a cardiomyocyte contractile improvement. In conclusion, the association of chronic aerobic exercise and low-dose L-NAME prevented cardiac pathological remodeling and induced cardiomyocyte contractile function improvement

NG-nitro-L-arginine methyl ester (L-NAME) have been widely used to inhibit constitutive NO synthase (NOS) in different biological systems. L-NAME commonly used for the induction of NO-deficient hypertension ^[1].

Freshly dissolved L-NAME was a 50 fold less potent inhibitor of purified brain NOS (mean IC₅₀= 70 μM) than L-NOARG (IC₅₀= 1.4 μM), but the apparent inhibitory potency of L-NAME approached that of L-NOARG upon prolonged incubation at neutral or alkaline pH. HPLC analyses revealed that NOS inhibition by L-NAME closely correlated with hydrolysis of the drug to L-NOARG^[1].

IL-NAME and the related compound L-NA (100 μM) constricted pressurized vessels (Sprague–Dawley rats) with myogenic tone. Removal of the endothelium did not cause constriction or alter myogenic tone, however the constrictor effect of L-NAME persisted. The constrictor effect of L-NAME was abolished by L-arginine (1 mM)^[2].

References:
[1]: Pfeiffer S, Leopold E, et al. Inhibition of nitric oxide synthesis by NG-nitro-L-arginine methyl ester (L-NAME): requirement for bioactivation to the free acid, NG-nitro-L-arginine. Br J Pharmacol. 1996 Jul;118(6):1433-40.
[2].Murphy TV, Kotecha N, et al. Endothelium-independent constriction of isolated, pressurized arterioles by Nomega-nitro-L-arginine methyl ester (L-NAME). Br J Pharmacol. 2007 Jul;151(5):602-9. doi: 10.1038/sj.bjp.0707262. Epub 2007 Apr 30.