Abstract
The aim of this study was to investigate the exact mechanism of interaction between nitric oxide (NO) and vasoactive intestinal polypeptide (VIP) as inhibitory non-adrenergic non-cholinergic (NANC) neurotransmitters in isolated smooth muscle cells and smooth muscle strips of the pig gastric fundus. In isolated smooth muscle cells, the maximal relaxant effect of VIP (10 −9 M) was inhibited by 94% by the NO synthase (NOS) inhibitor N G-nitro- l-arginine ( l-NA, 10 −4 M) and by 85% by the inducible NOS (iNOS)-selective inhibitor N-(3-(aminomethyl)-benzyl)acetamide (1400W; 10 −6 M). The relaxant effect of VIP was reduced by more than 70% by the guanylyl cyclase inhibitor 1 H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one (ODQ; 10 −6 M), the glucocorticoid dexamethasone (10 −5 M) and three protein kinase A inhibitors: ( R)- p-cyclic adenosine-3′,5′-monophosphothioate (( R)- p-cAMPS; 10 −6 M), {(8 R,9 S,11 S)-(−)-9-hydroxy-9- n-hexylester-8-methyl-2,3,9,10-tetrahydro-8,11-epoxy-1 H,8 H,11 H-2,7 b,11 a-triazadibenzo[ a, g]cycloocta[ cde]-trin-den-1-one} (KT5720; 10 −6 M) and N-(2-( p-bromo-cinnamylamino)ethyl))-5-isoquinoline sulfonamide dihydrochloride (H-89; 10 −5 M). In contrast, no influence of the NOS inhibitors, ODQ, dexamethasone, nor the protein kinase A inhibitors could be observed on the relaxant effect of VIP in smooth muscle strips. These data demonstrate that the experimental method completely changes the influence of NOS inhibitors on the relaxant effect of VIP in the pig gastric fundus. The isolation procedure of the smooth muscle cells might induce iNOS that can be activated by VIP.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.