Nitrergic stimulation of the locus coeruleus modulates blood pressure and heart rate in the anaesthetized rat

Abstract

To investigate whether nitric oxide is involved in the cardiovascular responses mediated via the locus coeruleus, the effects of microinjections of L-arginine and L-glutamate into the locus coeruleus on blood pressure and heart rate were investigated in sodium pentobarbitone-anaesthetized rats. Unilateral microinjection of L-arginine (25, 50 nmol) elicited dose-related depressor (-17 ± 4, -25 ± 4 mmHg) and bradycardic (13 ± 3, 24 ± 6 b.p.m.) effects. Furthermore, these effects were attenuated by prior local microinjection of N(G)-nitro-L-arginine (40 nmol). Peripheral muscarinic receptor blockade with atropine methyl nitrate (1 mg/kg, i.v.) attenuated the bradycardic but not the depressor re..