endothelin-1 and rhyncophylline

Rhynchophylline (Rhy) is a major ingredient of Uncaria rhynchophylla (UR) used to reduce blood pressure and ameliorate brain ailments. This study was to examine the role of Rho kinase (ROCK) in the inhibition of Rhy on contraction of cerebral arterioles caused by endothelin 1 (ET-1).. Cerebral arterioles of male Wistar rats were constricted with ET-1 for 10 min followed by perfusion of Rhy for 20 min. Changes in the diameters of the arterioles were recorded. The effects of Rhy on contraction of middle cerebral arteries (MCAs) were determined by a Multi-Myograph. Western blotting and immunofluorescent staining were used to examine the effects of Rhy on RhoA translocation and myosin phosphatase target subunit 1 (MYPT1) phosphorylation.. In vivo, Rhy (30-300 µM) relaxed cerebral arterioles constricted with ET-1 dose-dependently. In vitro, Rhy at lower concentrations (1-100 µM) caused relaxation of rat MCAs constricted with KCl and Bay-K8644 (an agonist of L-type voltage-dependent calcium channels (L-VDCCs)). Rhy at higher concentrations (>100 µM) caused relaxation of rat MCAs constricted with ET-1, which was inhibited by Y27632, a ROCK׳s inhibitor. Western blotting of rat aortas showed that Rhy inhibited RhoA translocation and MYPT1 phosphorylation. Immunofluorescent staining of MCAs confirmed that phosphorylation of MYPT1 caused by ET-1 was inhibited by Rhy.. These results demonstrate that Rhy is a potent inhibitor of contraction of cerebral arteries caused by ET-1 in vivo and in vitro. The effect of Rhy was in part mediated by inhibiting RhoA-ROCK signaling.

Topics: Animals; Arterioles; Cerebrum; Dose-Response Relationship, Drug; Endothelin-1; Indole Alkaloids; Male; Oxindoles; Phosphorylation; Protein Phosphatase 1; Rats; Rats, Wistar; rho-Associated Kinases; Uncaria; Vasoconstriction; Vasodilation

To investigate the effects of Listeriolysin O (LLO) on morphology, nitric oxide (NO) and endothelin-1 (ET-1) release by rat intestinal microvascular endothelial cells (RIMECs). We aimed to elucidate a preliminary therapeutic mechanism of action of rhynchophylline and isorhynchophylline (active components of Uncaria rhynchophylla) on listeriosis treatment and how they regulate the LLO-induced parasecretion of vasoactive agents in RIMECs. A RIMECs injury model was established by stimulating the cells with different concentrations of LLO. Compared with NC, LLO stimulation caused a dose-dependent decrease in RIMECs viability. After 12h, the levels of secreted NO and ET-1 were higher than NC and the ratio of NO:ET-1 decreased. The mRNA expression results of iNOS and ET-1 mRNA show the same trend. These deleterious effects could be partially reversed by the addition of rhynchophylline and isorhynchophylline at the same time as LLO. By preventing the morphological changes, decreasing cell death, and preventing disordered NO and ET-1 production in RIMECs induced by LLO, rhynchophylline and isorhynchophylline may help improve therapy for listeriosis.

Topics: Animals; Bacterial Toxins; Cells, Cultured; Endothelial Cells; Endothelin-1; Gene Expression Regulation; Heat-Shock Proteins; Hemolysin Proteins; Indole Alkaloids; Molecular Structure; Nitric Oxide; Nitric Oxide Synthase Type II; Oxindoles; Rats; Rats, Wistar