Evidence that pharmacological manipulations of central l-arginine-NO pathway influence blood pressure and heart rate in rats

In the present study we have investigated whether pharmacological manipulations of central l-arginine-nitric oxide (l-Arg-NO) pathway could affect blood pressure (BP) and heart rate (HR) in normotensive rats either untreated or pretreated with E. coli lipopolysaccharide (LPS). The intracerebroventricular injection (i.c.v.) of Nω-nitro-l-arginine methyl ester (l-NAME), an inhibitor of NO synthesis, caused a fall of BP and HR in LPS-treated but not in control rats. Furthermore, the pressor responses to i.c.v. injection of N-methyl-d-aspartate (NMDA) were enhanced by l-Arg or LPS treatment and, in both cases, this potentiation was blocked by l-NAME. The present results show that in some experimental conditions, such as activation of NMDA receptors or LPS pretreatment, the central microinfusion of drugs affecting the l-Arg-NO pathway may interfere with BP and HR. © 1992.