Vasorelaxant effect of novel Rho-kinase inhibitors on isolated thoracic aorta rings and underlying mechanisms / 中国药理学通报

Aim To evaluate the vasorelaxant effect of two new chemical entities, J35242 and J35243, on iso-lated rat thoracic aorta rings as Rho-kinase inhibitors, and further to explore the underlying mechanisms of these two compounds. Methods Isolated rat thoracic aorta rings pre-contracted by KCl or norepinephrine ( NE) were used to evaluate the vasodilatory effect of J35242 and J35243 . Through the interventions of sev-eral tool drugs, the mechanisms of compounds concern-ing endothelium, K+ channels and Ca2+ were studied. Results J35242 and J35243 showed potent relaxant effect on both KCl and NE pre-contracted vessels, and exhibited partial endothelium dependency. L-NAME and Methylene Blue( MB) could influence the relaxant effect of these compounds. Meanwhile, the compounds could inhibit intracellular Ca2+ release and extracellu-lar Ca2+ influx, which indicated that the compounds might block the calcium channels to relax the vessels. In addition, the two compounds probably did not dilate the aorta rings through opening potassium channels. Conclusions J35242 and J35243 have vasorelaxant effects on vessels in vitro and the potency of J35242 is stronger than that of J35243 . The underlying mecha-nisms might be endothelium-dependent. Also the com-pounds might block Ca2+ channels, lowering intracel-lular Ca2+ concentration to relax the vessels.

Preliminary study on pharmacokinetics of DL0805-1:a novel Rho kinase inhibitor in rats / 中国药理学通报

Aim ToestablishthemethodofHighper-formance liquid chromatography ( HPLC ) for detecting plasma concentration of indazole compound DL0805-1 , a Rho kinase inhibitor, and to investigate its pharma-cokinetics in rats with intravenous injection. Methods ThedetectingsystemwasAgilent1200-DAD;chro-matographic column was Agilent TC-C18 ( 4. 6 mm × 250 mm, 5 μm); the ultraviolet detection wavelength was 235 nm; the column temperature was 35 ℃; the flow rate was 1 ml·min-1;the mobile phase was ace-tonitrile-0. 05% H3 PO4 gradient elute. Rat blood sam-ples were collected at different intervals after intrave-nous injection of a single dose of DL0805-1 , and the concentration of DL0805-1 in rat plasma were deter-mined by HPLC method for estimating pharmacokinetic parameters.Results Afterintravenousinjectionof DL0805-1 in rats, prototype and its metabolite were detected in plasma. T1/2 of DL0805-1=(2. 34 ± 1. 42) h, Cmax=(3. 51 ± 0. 44) mg·L-1, T1/2 of metabolite of DL0805-1 = ( 1. 27 ± 0. 45 ) h, Cmax = ( 3. 55 ± 0.22)mg·L-1.Conclusion Theseresultssuggest that DL0805-1 may be metabolized into another sub-stance in vivo and play biological functions. The meth-od is sensitive, simple, and accurate, and can be used for the determination of DL0805-1 in rat plasma and pharmacokinetic studies.

Vasorelaxant effect of Rho kinase inhibitor DL0805-0 on isolated rat aortic rings and its underlying mechanisms / 中国药理学通报

Aim To investigate the in vitro vasorelax-ant effect of DL0805-0, a Rho kinase inhibitor, on iso-lated rat thoracic aorta and explore its underlying mechanism. Methods Tension was measured to eval-uate the vasorelaxant effect of DL0805-0 on rat endo-thelium-intact and endothelium-denuded thoracic aorta rings. Rho kinase inhibitor fasudil, nitric oxide syn-thase inhibitor Nω-nitro-L-arginine methyl ester ( L-NAME), guanylate cyclase inhibitor methylene blue, cyclooxygenase inhibitor indomethacin, calcium-activa-ted potassium channel blocker tetraethyl ammonium ( TEA ) , ATP-sensitive potassium channel blocker glibenclamide and voltage-dependent potassium chan-nel blocker 4-aminopyridine ( 4-AP ) were used to il-lustrate the mechanisms of vasorelaxant effect of DL0805-0 . Results DL0805-0 exerted vasorelaxation in a dose-dependent manner in KCl (60 mmol·L-1 ) or NE ( 0. 1 μmol · L-1 ) -induced contraction. DL0805-0-induced vasorelaxation was significantly re-duced by L-NAME. However, methylene blue and in-domethacin did not significantly affect vasorelaxation of DL0805-0. In endothelium-denuded rings, TEA re-markably attenuated the vasorelaxant effect of DL0805-0 , while glibenclamide and 4-AP did not affect vasore laxation of DL0805-0 significantly. DL0805-0 also re-duced NE-induced transient contraction and inhibited contraction induced by increasing extracellular calci-um. Conclusion These results suggest that DL0805-0 induces vasorelaxation through an endothelium-depend-ent pathway. The opening of calcium-activated K+channels and blocking of Ca2+ channels in vascular smooth muscle cells may be one of the mechanisms of DL0805-0-induced vasorelaxation.