Participation of nitric oxide and N-methyl-D-aspartic acid receptors in the pressor response to intrathecal injected noradrenaline at the spinal cord of the rat.
In pentobarbital-anesthetized rats, intrathecal injection of noradrenaline (NA; 6, 18 and 60 nmol) induced a dose-dependent increase in the mean blood pressure. The pressor response to NA (18 nmol) was blocked by pretreatment with the selective antagonist for N-methyl-D-aspartic acid (NMDA) receptors, 2-amino-5-phosphonovaleric acid (30 nmol), but not by pretreatment with the selective antagonist for (+/-)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid/kainate receptors, 6,7-dinitroquinoxaline-2,3-dione (50 nmol). The pressor effect of NA was reduced after pretreatment with N(G)-nitro-L-arginine methyl ester (L-NAME, 1 micromol). The effect of L-NAME on the pressor response to NA was reverted by the precursor of nitric oxide (NO), L-arginine (5 micromol). The hypertension induced by NA was also reduced by the guanylate cyclase inhibitor methylene blue (0.3 micromol). These results suggest that spinal NMDA receptors and spinal NO are involved in the pressor response to NA.
García
María del Carmen
Mdel C
Cátedra de Farmacología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina. mgarcia@huemul.ffyb.uba.ar
Celuch
Stella Maris
SM
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D005260:Female; D007278:Injections, Spinal; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000502:physiology*; D013116:Spinal Cord / Q000187:drug effects* / Q000502:physiology
D016194:Receptors, N-Methyl-D-Aspartate; D009569:Nitric Oxide; D009638:Norepinephrine