INFLUENCE OF INTRACEREBROVENTRICULAR INJECTION OF SODIUM NITROPRUSSIDE L-ARGININE AND N^G-NITRO-L-ARGININE ON CARDIOVASCULAR ACTIVITY IN CONSCIOUS RATS

In order to study the cardiovascular effect of NO in conscious rats, sodium nitroprusside(SNP), the precursor of NO(L-Arginine, Arg-Arg) and one of the inhibitor of NOS (N^G nitro L-arginine, NNLA) were intracerebroventricularly(icv) injected. Our experimental results indicated that, an apparant dose-dependent hypertensive effect was produced by icv administration of SNP (8, 16, 32 and 32 μg), a tachycardiac effect was also produced at the same time. In addition, hypertention and tachycardia were produced by icv L-arginine and the dipeptide Arg-Arg. Futhermore. a hypotensive and bradycardiac effect can be produced by icv NNLA. These results suggest that there is a positive effect on cardiovascular activity due to increase of endogeneuse NO in the rat brain and a negative effect on cardiovascular activity due to decrease of endogeneuse NO in the rat brain.