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  • Title: The intercellular communication via nitric oxide and its regulation in coupling of cyclic GMP synthesis upon stimulation of muscarinic cholinergic receptors in rat superior cervical sympathetic ganglia.
    Author: Ando M, Tatematsu T, Kunii S, Nagata Y.
    Journal: Brain Res; 1994 Jul 11; 650(2):283-8. PubMed ID: 7525017.
    Abstract:
    Cyclic GMP (cGMP) production in rat superior cervical sympathetic ganglia (SCG) was markedly increased (ca. 7-9-fold) by the addition of either acetylcholine (ACh; 0.1 mM) or a muscarinic agonist, carbachol (Carb; 0.1 mM), in the presence of an inhibitor (3-isobutyl-1-methylxanthine) for cGMP hydrolytic enzyme during in vitro aerobic incubation at 37 degrees C for 5 min. The ACh-induced accumulation of cGMP in SCG was effectively blocked (-73%) by the further addition of atropine (10 microM), a muscarinic antagonist, whereas a nicotinic blocker, hexamethonium (10 microM) partially antagonized (-41%) this ACh stimulation. The inhibitory effect of hexamethonium on ACh-evoked ganglionic cGMP production was effectively augmented (-83%) by addition of NG-monomethyl-L-arginine (L-NMMA, 50 microM), a compound that inhibits nitric oxide (NO) synthesis from L-arginine. Comparable inhibition of cGMP formation was observed following application of L-NMMA to the SCG upon stimulation of Carb. In contrast, L-NMMA had no effect on the decreased level of ACh-evoked cGMP production caused by the muscarinic antagonist. The Carb-induced elevation of ganglionic cGMP synthesis was significantly reduced within 1 min of incubation in the medium containing hemoglobin (Hb; 20 microM), an agent that scavenges only the extracellular fraction of NO. Thereafter, the tissue cGMP formation attenuated to the control level by subsequent incubation for several minutes. Addition of protein kinase C (PKC) activator, 12-O-tetradecanoylphorbol 13-acetate (TPA; 1 microM) to the medium significantly decreased Carb-evoked cGMP synthesis (-61%) in SCG, whereas superoxide dismutase (SOD; 30 U/ml) only slightly suppressed the Carb stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)
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