cyclic-gmp and rutecarpine

To investigate the effect and potential mechanisms of rutaecarpine (Rut) in a rat artery balloon-injury model.. The intimal hyperplasia model was established by rubbing the endothelia with a balloon catheter in the common carotid artery (CCA) of rats. Fifty rats were randomly divided into five groups, ie. sham, model, Rut (25, 50 and 75 mg/kg) with 10 rats of each group. The rats were treated with or without Rut (25, 50, 75 mg/kg) by intragastric administration for 14 consecutive days following injury. The morphological changes of the intima were evaluated by hematoxylin-eosin staining. The expressions of proliferating cell nuclear antigen (PCNA) and smooth muscle (SM) α-actin in the ateries were assayed by immunohistochemical staining. The mRNA expressions of c-myc, extracellular signal-regulated kinase 2 (ERK2), MAPK phosphatase-1 (MKP-1) and endothelial nitric oxide synthase (eNOS) were determined by real-time reverse transcription-polymerase chain reaction. The protein expressions of MKP-1 and phosphorylated ERK2 (p-ERK2) were examined by Western blotting. The plasma contents of nitric oxide (NO) and cyclic guanosine 3',5'-monophosphate (cGMP) were also determined.. Compared with the model group, Rut treatment significantly decreased intimal thickening and ameliorated endothelial injury (P<0.05 or P<0.01). The positive expression rate of PCNA was decreased, while the expression rate of SM α-actin obviously increased in the vascular wall after Rut (50 and 75 mg/kg) administration (P<0.05 or P<0.01). Furthermore, the mRNA expressions of c-myc, ERK2 and PCNA were downregulated while the expressions of eNOS and MKP-1 were upregulated (P<0.05 or P<0.01). The protein expressions of MKP-1 and the phosphorylation of ERK2 were upregulated and downregulated after Rut (50 and 75 mg/kg) administration (P<0.05 or P<0.01), respectively. In addition, Rut dramatically reversed balloon injury-induced decrease of NO and cGMP in the plasma (P<0.05 or P<0.01).. Rut could inhibit the balloon injury-induced carotid intimal hyperplasia in rats, possibly mediated by promotion of NO production and inhibiting ERK2 signal transduction pathways.

Topics: Actins; Animals; Carotid Arteries; Carotid Artery Injuries; Cyclic GMP; Disease Models, Animal; Gene Expression Regulation; Hyperplasia; Indole Alkaloids; Male; Nitric Oxide; Phosphorylation; Proliferating Cell Nuclear Antigen; Quinazolines; Rats, Sprague-Dawley; RNA, Messenger; Tunica Intima

Rutaecarpine (Rut) has been shown to induce hypotension and vasorelaxation. In vitro studies indicated that the vasorelaxant effect of Rut was largely endothelium-dependent. We previously reported that Rut increased intracellular Ca2+ concentrations ([Ca2+]i) in cultured rat endothelial cells (ECs) and decreased [Ca2+]i in cultured rat vascular smooth muscle (VSMCs) cells. The present results showed that the hypotensive effect of Rut (10-100 microgram/kg i.v.) was significantly blocked by the nitric oxide synthase inhibitor Nomega-nitro-L-arginine. In aortic rings, Rut (0. 1-3.0 microM)-induced vasorelaxation was inhibited by Nomega-nitro-L-arginine and hydroquinone but not by antagonists of the various K+ channels, 4-aminopyridine, apamin, charybdotoxin, or glibenclamide. Rut (0.1 and 1.0 microM) inhibited the norepinephrine-induced contraction generated by Ca2+ influx and at 1.0 microM increased cyclic GMP (cGMP) production in endothelium-intact rings and to a lesser extent in endothelium-denuded rings. In whole-cell patch-clamp recording, nonvoltage-dependent Ca2+ channels were recorded in ECs and Rut (0.1, 1.0 microM) elicited an opening of such channels. However, in VSMCs, Rut (10.0 microM) inhibited significantly the L-type voltage-dependent Ca2+ channels. In ECs cells, Rut (1.0, 10.0 microM) increased nitric oxide release in a Ca2+-dependent manner. Taken together, the results suggested that Rut lowered blood pressure by mainly activating the endothelial Ca2+-nitric oxide-cGMP pathway to reduce smooth muscle tone. Although the contribution seemed to be minor in nature, inhibition of contractile response in VSMCs, as evidenced by inhibition of Ca2+ currents, was also involved. Potassium channels, on the other hand, had no apparent roles.

Topics: 4-Aminopyridine; Alkaloids; Animals; Aorta, Thoracic; Calcium; Calcium Channels; Calcium Channels, L-Type; Cells, Cultured; Cyclic GMP; Endothelium, Vascular; Hydroquinones; In Vitro Techniques; Indole Alkaloids; Isometric Contraction; Male; Membrane Potentials; Models, Cardiovascular; Muscle, Smooth, Vascular; Nitroarginine; Norepinephrine; Patch-Clamp Techniques; Potassium Channel Blockers; Quinazolines; Rats; Rats, Sprague-Dawley; Vasodilation; Vasodilator Agents

In this study, rutaecarpine was tested for its antiplatelet activities in human platelet-rich plasma. In human platelet-rich plasma, rutaecarpine (40-200 microM) inhibited aggregation stimulated by a variety of agonists (i.e., collagen, ADP, adrenaline and arachidonic acid). The antiplatelet activity of rutaecarpine (120 microM) was not significantly attenuated by pretreatment with the nitric oxide synthase inhibitor N(G)-mono-methyl-L-arginine (L-NMMA) (100 microM) or N(G)-nitro-L-arginine methyl ester (L-NAME) (200 microM) and with the guanylyl cyclase inhibitor methylene blue (100 microM). In addition, rutaecarpine (40-200 microM) did not significantly affect cyclic AMP and cyclic GMP levels in human washed platelets, whereas it significantly inhibited thromboxane B2 formation stimulated by collagen (10 microg/ml) and thrombin (0.1 U/ml). Furthermore, rutaecarpine (40-200 microM) inhibited [3H]inositol monophosphate formation stimulated by collagen and thrombin in [3H]myoinositol-loaded platelets. It is concluded that the antiplatelet effects of rutaecarpine are due to inhibition of thromboxane formation and phosphoinositide breakdown.

Topics: Alkaloids; Blood Platelets; Cyclic AMP; Cyclic GMP; Humans; Indole Alkaloids; Nitric Oxide; Phosphatidylinositols; Platelet Aggregation; Platelet Aggregation Inhibitors; Quinazolines; Thromboxane B2