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Hypertension crisis is a severe disease and needs emergency treatment in clinic. It is an important task to discover novel drugs which could lower the blood pressure steadily and quickly. However, animal models for screening anti-hypertensive crisis agents are unsatisfactory. The present study aimed to establish a new hypertensive crisis rat model and then explore the therapeutic effects of three Rho-kinase inhibitors including Fasudil, DL0805-1 and DL0805-2 on such a disease model. The hypertensive crisis symptoms were developed on male Wistar rats by subcutaneously injecting small doses of norepinephrine (NE) for 10 days in the initial stage. A sudden increase in blood pressure (BP) was then induced by excessive NE infusion. Compounds to be tested were intravenously injected into the rats immediately when the rapidly increased systolic blood pressure appeared. The results have shown that after small dose administration with NE, the rats could obtain acute BP increase to a high level without sudden death when a large dose of NE was injected. Fasudil, DL0805-1 and DL0805-2 could lower the blood pressure quickly in a dose dependent manner and improve the survival rate. The compounds also prevent the animals from organ damage. In conclusion, we established a novel hypertensive crisis animal model which could evaluate agents within a short time. In this model, we found that three Rho-kinase inhibitors have potential therapeutic effects on hypertensive crisis. This work might contribute to the discovery and development of new anti-hypertensive crisis drugs., (Copyright © 2018 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Aim: DL0805-2 [N-(1H-indazol-5-yl)-1-(4-methylbenzyl) pyrrolidine-3-carboxamide] is a DL0805 derivative with more potent vasorelaxant activity and lower toxicity. This study was conducted to investigate the vasorelaxant mechanisms of DL0805-2 on angiotensin II (Ang II)-induced contractions of rat thoracic aortic rings in vitro., Methods: Rat thoracic aortic rings and rat aortic vascular smooth muscle cells (VSMCs) were pretreated with DL0805-2, and then stimulated with Ang II. The tension of the aortic rings was measured through an isometric force transducer. Ang II-induced protein phosphorylation, ROS production and F-actin formation were assessed with Western blotting and immunofluorescence assays. Intracellular free Ca(2+) concentrations were detected with Fluo-3 AM., Results: Pretreatment with DL0805-2 (1-100 μmol/L) dose-dependently inhibited the constrictions of the aortic rings induced by a single dose of Ang II (10(-7) mol/L) or accumulative addition of Ang II (10(-10)-10(-7) mol/L). The vasodilatory effect of DL0805-2 was independent of endothelium. In the aortic rings, pretreatment with DL0805-2 (1, 3, and 10 μmol/L) suppressed Ang II-induced Ca(2+) influx and intracellular Ca(2+) mobilization, and Ang II-induced phosphorylation of two substrates of Rho kinase (MLC and MYPT1). In VSMCs, pretreatment with DL0805-2 (1, 3, and 10 μmol/L) also suppressed Ang II-induced Ca(2+) fluxes and phosphorylation of MLC and MYPT1. In addition, pretreatment with DL0805-2 attenuated ROS production and F-actin formation in the cells., Conclusion: DL0805-2 exerts a vasodilatory action in rat aortic rings through inhibiting the Rho/ROCK pathway and calcium fluxes.

Purpose: In the present study, we investigated the vasodilatory effect of a novel scaffold Rho-kinase inhibitor, DL0805-2, on isolated rat arterial rings including mesenteric, ventral tail, and renal arteries. We also examined the potential mechanisms of its vasodilatory action using mesenteric artery rings., Methods: A DMT multiwire myograph system was used to test the tension of isolated small arteries. Several drugs were employed to verify the underlying mechanisms., Results: DL0805-2 (10(-7)-10(-4) M) inhibited KCl (60 mM)-induced vasoconstriction in three types of small artery rings (pEC50: 5.84 ± 0.03, 5.39 ± 0.03, and 5.67 ± 0.02 for mesenteric, renal, and ventral tail artery rings, respectively). Pre-incubation with DL0805-2 (1, 3, or 10 μM) attenuated KCl (10-60 mM) and angiotensin II (AngII; 10(-6) M)-induced vasoconstriction in mesenteric artery rings. The relaxant effect on the rat mesenteric artery was partially endothelium-dependent (pEC50: 6.02 ± 0.05 for endothelium-intact and 5.72 ± 0.06 for endothelium-denuded). The influx and release of Ca(2+) were inhibited by DL0805-2. In addition, the increased phosphorylation levels of myosin light chain (MLC) and myosin-binding subunit of myosin phosphatase (MYPT1) induced by AngII were blocked by DL0805-2. However, DL0805-2 had little effect on K(+) channels., Conclusions: The present results demonstrate that DL0805-2 has a vasorelaxant effect on isolated rat small arteries and may exert its action through the endothelium, Ca(2+) channels, and the Rho/ROCK pathway.