0000000000268686
AUTHOR
Maria Carmela Baffi
Signal transduction pathways involved in the mechanical responses to protease-activated receptors in rat colon.
Recording simultaneously in vitro the changes of endoluminal pressure (index of circular muscle activity) and isometric tension (index of longitudinal muscle activity), we examined the mechanisms responsible for the apamin-sensitive relaxant and contractile responses induced by protease-activated receptor (PAR)-1 and PAR-2 activating peptides, SFLLRN-NH2 and SLIGRL-NH2, respectively, in rat colon. In the circular muscle, the inhibitory effects of SFLLRN-NH2 and SLIGRL-NH2 were significantly reduced by ryanodine, an inhibitor of Ca2+ release from the sarcoplasmic reticulum, but unaffected by 1-[6-[[17beta-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione (U73122), a phosph…
Dual effect mediated by protease-activated receptors on the mechanical activity of rat colon
1. The present study examined the mechanical effects of agonist enzymes and receptor-activating peptides for protease-activated receptor (PAR)-1 and PAR-2 on longitudinal and circular muscle of rat isolated colonic segments in the attempt to clarify the PAR functional role in intestinal motility. 2. The responses to PAR-1 and PAR-2 activation were examined in vitro by recording simultaneously the changes of endoluminal pressure (index of circular muscle activity) and of isometric tension (index of longitudinal muscle activity). 3. Both PAR-1 agonists, thrombin (0.1 nM - 3 microM) and SFLLRN-NH2 (1 nM - 3 microM), and PAR-2 agonists, trypsin (0.1 nM - 10 microM) and SLIGRL-NH2 (1 nM - 10 mic…
Involvement of nitric oxide and tachykinins in the effects induced by protease-activated receptors in rat colon longitudinal muscle
The aim of the present study was to verify a possible involvement of nitric oxide (NO) and of tachykinins in the contractile and relaxant effects caused by the activation of protease-activated receptor (PAR)-1 and PAR-2 in the longitudinal muscle of rat colon. Mechanical responses to the PAR-1 activating peptides, SFLLRN-NH2 (10 nM–10 μM) and TFLLR-NH2 (10 nM–10 μM), and to the PAR-2-activating peptide, SLIGRL-NH2 (10 nM–10 μM), were examined in vitro in the absence and in the presence of different antagonists. The relaxation induced by SFLLRN-NH2, TFLLR-NH2 and SLIGRL-NH2 was antagonised by the inhibitor of NO synthase L-Nω-nitroarginine methyl ester (300 μM), or by the inhibitor of the gu…