DIFFERENTIAL REGULATION OF CYCLIC-GMP LEVELS IN THE FRONTAL-CORTEX AND THE CEREBELLUM OF ANESTHETIZED RATS BY NITRIC-OXIDE - AN IN-VIVO MICRODIALYSIS STUDY
Jt. Laitinen et al., DIFFERENTIAL REGULATION OF CYCLIC-GMP LEVELS IN THE FRONTAL-CORTEX AND THE CEREBELLUM OF ANESTHETIZED RATS BY NITRIC-OXIDE - AN IN-VIVO MICRODIALYSIS STUDY, Brain research, 668(1-2), 1994, pp. 117-121
A microdialysis method combined with a sensitive radioimmunoassay was
used to monitor extracellular cyclic GMP (cGMP) levels in the frontal
cortex and the cerebellum of anesthetized rats in vivo. Basal cGMP rel
ease remained constant throughout the perfusion period and was approxi
mate to 2 fmol/30 min in the frontal cortex and approximate to 4 fmol/
30 min in the cerebellum. The nitric oxide (NO) donor sodium nitroprus
side (SNP) stimulated cGMP release transiently in both regions. Howeve
r, the maximal response was 3-fold in the frontal cortex (obtained wit
h 5 mu M SNP) but 90-fold in the cerebellum (obtained with 1 mM SNP).
Perfusion with the NO synthase (NOS) inhibitor N-G-nitro-L-arginine me
thyl ester (L-NAME) suppressed cerebellar cGMP release by 74% indicati
ng that NO is the major regulator of basal cGMP levels in the cerebell
um. Quite opposite, L-NAME exhibited no potency in the frontal cortex
suggesting that other activators of guanylyl cyclase may regulate basa
l cortical cGMP levels in vivo.