Endothelin-1 and nitric oxide mediated the lipopolysaccharide-induced cardiac negative inotropic role / 中国应用生理学杂志

<p><b>AIM</b>To investigate the effects of endothelin-1 (ET-1) and nitric oxide (NO) on lipopolysaccharide(LPS)-induced myocardial dysfunction, and explore the related underlying mechanisms.</p><p><b>METHODS</b>Experimental septic model was established by intraperitoneal injection of LPS (10 mg x kg(-1)). The study was carried out on the isolated rat hearts to determine the roles of ET-1 and NO in the effect of LPS on the cardiac contractility and on the isolated rat ventricular myocytes model to observe the [Ca2+]i homeostasis in cardiac myocytes.</p><p><b>RESULTS</b>(1) The levels of serum NO2-/NO3- and plasma ET-1 were markedly increased by LPS treatment for 4 hours. (2) LPS induced the decrease in rate-pressure product (RPP), and increase in left ventricular end-diastolic pressure (LVEDP) in the isolated perfused rat hearts. Pretreatment with either aminoguanidine (AMG) (100 mg x kg(-1), i.p.) or BQ-123 (1 mg x kg(-1), i.p.) partially attenuated LPS-induced myocardial depression. When these two drugs were simultaneously given, myocardial depression elicited by LPS was almost abolished. (3) LPS significantly decreased the amplitude of caffeine induced [Ca2+]i transients compared to the control cells. The activity of SR Ca22+ -ATPase was significantly decreased in the cardiac myocytes from LPS-treated rats. Single pretreatment with either AMG or BQ-123 did not attenuate the impairment of SR Ca2+ -ATPase induced by LPS.</p><p><b>CONCLUSION</b>ET-1 and NO mediate myocardial dysfunction in hearts isolated and decrease [Ca2+]i transients in cardiac myocytes from LPS-treated rats. But neither ET-1 nor NO participates in the impairment of SR Ca2+ -ATPase induced by LPS.</p>

Epithelial K⁺ channels: driving force generation and K⁺ recycling for epithelial transport with physiological and clinical implications / 生理学报

K(+) channels form a large family of membrane proteins that are expressed in a polarized fashion in any epithelial cell. Based on the transmembrane gradient for K(+) that is maintained by the Na(+)-K(+)-ATPase, these channels serve two principal functions for transepithelial transport: generation of membrane voltage and recycling of K(+). In this brief review, we will outline the importance of this ancient principle by examples of epithelial transport in the renal proximal tubule and gastric parietal cells. In both tissues, K(+) channel activity is rate-limiting for transport processes across the epithelial cells and essential for cell volume regulation. Recent experimental data using pharmacological tools and genetically modified animals have confirmed the original physiological concepts and specified the knowledge down to the molecular level. The development of highly active and tissue selective small molecule therapeutics has been impeded by two typical features of K(+) channels: their molecular architecture challenges the design of molecules with high affinity binding and they are expressed in a variety of tissues at the same time. Nevertheless, new insights into pathophysiology, e.g. that K(+) channel inhibition can block gastric acid secretion, render the clinical use of K(+) channel drugs in gastric disease and as kidney transport inhibitors highly attractive.

The alterations of nitric oxide synthase activity of ventricular cardiac muscle of rats in two septic shock models / 中国应用生理学杂志

<p><b>AIM</b>To observe the differences of hemodynamics and nitric oxide synthase(NOS) activity of ventricular cardiac muscle in two septic shock models and explore the possible mechanism.</p><p><b>METHODS</b>Two rat models of septic shock[lipopolysaccharide(LPS)-induced and cecal ligation and puncture (CLP)-induced septic shock] were used. The hemodynamic parameters and nitric oxide synthase activity of ventricular cardiac muscle were measured.</p><p><b>RESULTS</b>The hemodynamic parameters in CLP-induced model were increased in the early stage and decreased in the late stage while in LPS-induced model the parameters showed the same change of the CLP late stage. Both LPS model and CLP model (late stage) showed significant increase in NOS activity, but there was no difference between the two models. After treatment of the NOS inhibitor N-nitro-L-arginine methyl ester (L-NAME), the parameters of CLP-late stage and LPS model increased significantly. The NOS activity reached the highest level in the CLP-middle stage. The production of nitrite/nitrate decreased significantly in LPS model and CLP model(late stage) after treatment of L-NAME, but the nitrite/nitrate produced by constitutive NOS in LPS model was higher than CLP model(late stage).</p><p><b>CONCLUSION</b>The increase of the NOS activity may be the main reason to lead to the depression of the hemodynamic parameters. Inducible NOS may play the leading role in the LPS model while cNOS and iNOS have the same effect in the CLP model.</p>

Effect of cinobufacini on vascular contractile of rat thoracic aorta / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To examine the effect of cinobufacini on rat thoracic aorta and its mechanism.</p><p><b>METHODS</b>Isolated rat thoracic aorta was perfused and isometric tension was recorded by organ bath technique before and after cinobufacini treatment.</p><p><b>RESULT</b>Cinobufacini induced contraction of isolated thoracic aorta with or without endothelium in a concentration-dependent manner (at concentration of 2.5,5.0,7.5,10.0 g/L). The vasoconstriction effect of cinobufacini was more potent in endothelium-denuded aorta ring [(16.3+/-3.39)%, (52.5+/-7.70)%, (60.9+/-8.84)%, (69.2+/-11.34)%] than in endothelium-intact aorta ring [(6.2+/-2.07)%, (14.7+/-4.91), (17.6+/-5.86)%, (20.3+/-6.78)% (P<0.01)]. Its contractile effect was attenuated in Ca(2+)-free solution (about 1/10 of that in buffer with 1.25 mmol/L CaCl(2)) or by the treatment with verapamil (10(-7)mol/L), an L-type calcium channel antagonist. Cinobufacini induced contraction on the endothelium-intact rat aorta was augmented by pretreatment with L-NAME (10(-4)mol/L), a nitric oxide synthase inhibitor.</p><p><b>CONCLUSION</b>Cinobufacini contracts rat thoracic aorta by opening the voltage-dependent Ca(2+) channel and increasing Ca(2+) influx into vascular smooth muscle. Cinobufacini can also stimulate the release of vascular relaxant factor, nitric oxide, from the endothelium and thus antagonize cinobufacini-induced contraction.</p>

Relaxant effect of Astragalus membranaceus on smooth muscle cells of rat thoracic aorta / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To investigate the effect of Astragalus membranaceus(AM) on vascular circles and the underlying mechanisms.</p><p><b>METHODS</b>The study was performed with the model of isolate rat thoracic aorta rings in organ bath. When the endothelium of rat thoracic aorta was removed,the effect of accumulated AM on aorta rings in resting tension, or pre-constricted with KCl, or pre-constricted with phenylephrine (PE) was observed. And to explove the mechanism, the aorta rings were incubated with Ca(2+)-free medium alone, or Ca(2+)-free medium plus heparin, or propranolol alone before pre-contraction with PE.</p><p><b>RESULTS</b>AM had no significant effects on aorta rings in resting tension or pre-constricted with KCl. When the concentration of AM was cumulated to 10(-1), 3 x 10(-1),10(0), 3 x 10(0) g/L, it caused concentration-dependent relaxation while aorta rings were pre-constricted with PE(3 x 10(-7)mol/L), compared with the control [(90.4 +/-4.2)% compared with (94.7 +/-2.4)%,(86.1 +/-5.0)% compared with (92.6 +/-3.2)%, (82.3 +/-5.9)% compared with (90.4 +/-3.6) %, (78.3 +/-6.0)% compared with (88.1 +/-4.0)%]. This effect was not inhibited by Ca(2+)-free medium or propranolol alone. However, the effect was attenuated by the co-incubation with heparin and Ca(2+)-free medium [without heparin:(76.2+/-4.3)% compared with (92.3 +/-5.9)%, with heparin: (95.3+/-0.5)% compared with (95.1+/-0.6)%].</p><p><b>CONCLUSION</b>The results indicate that AM can relax the rat thoracic aorta rings without endothelium. The mechanism may include the inhibition of intracellular calcium ions release by the 1,4,5-triphosphate inositol-receptor-dependent pathway in vascular smooth muscle cells.</p>

Endothelium-independent vasorelaxant effect of puerarin on rat thoracic aorta / 中国中药杂志

<p><b>OBJECTIVE</b>To investigate the vasorelaxant effect of puerarin in rat aortic rings and the mechanism.</p><p><b>METHOD</b>The isolated thoracic aortic rings of male Sprague-Dawley rats were mounted on the organ bath and the contractile responses of the vessel were recorded.</p><p><b>RESULT</b>Puerarin completely relaxed the contractions induced by phenylephrine in a concentration-dependent manner in endothelium-intact and endothelium-denuded rat aorta, but it had no effect on those preconstricted by a high concentration of potassium chloride (KCl, 60 mmol x L(-1)). The relaxant effect of puerarin was significantly inhibited by pretreatment of endothelium-denuded aorta with potassium channel antagonists tetraethylammonium, 4-aminopyridine but not glibenclamide.</p><p><b>CONCLUSION</b>Puerarin induces an endothelium-independent relaxation in rat aortic rings. The mechanisms may involve the reduction in Ca2+ influx through the calcium channels operated by alpha-adrenergic receptor and the activation of the potassium channels (Kv and BKca, but not KATP).</p>

NO/cGMP signal pathway involved in the disturbance of calcium homeostasis in vascular smooth muscle during the late phase of sepsis / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To evaluate the alterations in calcium metabolism of the vascular smooth muscle of rat thoracic aorta in the late phase of sepsis and to investigate the involvement of nitric oxide (NO)/cyclic-GMP(cGMP) signal transduction pathway in the sepsis-induced vascular hyporeactivity.</p><p><b>METHODS</b>Male Sprague-Dawley rats were subjected to sepsis by cecal ligation and puncture (CLP). Eighteen hours post CLP, rat aortic rings were removed for measurement of contractile responses to vasoconstrictors by using organ bath technique.</p><p><b>RESULT</b>In endothelium intact aortic rings from CLP rats, concentration-contraction curves to phenylephrine (PE) and high KCl were significantly decreased when compared with those from control rats. The transient contraction induced by PE in calcium-free Krebs solution and the concentration-dependent contraction to CaCl(2)in KCl-depolarized medium were also markedly reduced. The hyporeactivity to vasoconstrictors was completely reversed by pretreatment either with aminoguanidine (AMG), a selective inducible nitric oxide synthase inhibitor, or with 1H [1,2,4] oxadiazolo[4,3-a] quininoxalin-1-one(ODQ), an inhibitor of NO-sensitive guanylyl cyclase.</p><p><b>CONCLUSION</b>A generalized impairment in calcium handling in vascular smooth muscle,including the calcium influx through the voltage-operated and receptor-operated channels and calcium release from intracellular calcium stores, is involved in vascular hyporeactivity during the late phase of sepsis. The NO/cGMP signal transduction pathway might be involved in this defect in vascular smooth muscle.</p>

Modulation of iron on the vasodilating effect of interleukin-2 in the isolated aortic ring / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To explore the effect and mechanism of iron on the vasodilating effect of interleukin-2 (IL-2) in the isolated aortic ring.</p><p><b>METHODS</b>Isometric tension was recorded in response to drugs in organ bath. Ferric ammonium citrate (FAC) was added to the bath 30 min before phenylephrine (1 micromol/L), which was followed by IL-2 in a cumulative fashion. Spectrophotometry was used to determine the activity of nitric oxide synthase (NOS) of the thoracic aorta.</p><p><b>RESULTS</b>FAC (0.1 - 10 micromol/L) alone did not affect the tension of rings,but inhibited the vasodilating effect of IL-2 (1 - 1,000 U/ml) in a dose dependent manner. IL-2(1, 10, 100, 1000 U/ml) decreased the aortic tension to (78.47+/-4.31)%, (66.86+/-5.55)%, (52.62+/-4.51)% and (42.39+/-4.27)% of pre-drug control, respectively. However, after incubation with 10 micromol/L FAC in the presence of IL-2, the aortic tension was reduced to (89.81+/-1.94)%, (86.13+/-3.11)%, (77.16+/-5.66)% and (68.76+/-5.69)% of pre-drug control, respectively. Pretreatment with L-arginine (1 mmol/L) abolished the inhibitory effect of FAC. Pretreatment with FAC attenuated the increased activity of NOS induced by IL-2 from (22.10+/-1.87)U/mg prot to (15.71+/-0.89)U/mg prot. High Ca(2+) (2.5 mmol/L) incubation did not change the inhibitory effect of FAC. Pretreatment with FAC attenuated the increased caffeine-releasable pool of Ca(2+) by IL-2. High K(+) (10 mmol/L) incubation abolished the inhibitory effect of FAC.</p><p><b>CONCLUSION</b>FAC inhibits the vasodilating effect of IL-2 in the isolated aortic ring,which may be mediated by decreasing the activity of NOS. Intracellular calcium release and inward rectifier potassium channel are involved in the inhibitory effect of FAC.</p>

Treatment of interferon-alpha in reducing the endothelium-dependent relaxation of rat thoracic aorta / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To investigate the vascular effect of acute and chronic treatment of interferon-alpha (IFN-alpha) in rat aortic rings.</p><p><b>METHODS</b>Isolated thoracic aortic rings were mounted on the organ bath and the tension of the vessel was recorded.</p><p><b>RESULTS</b>IFN-alpha(10, 100, 1,000 and 10,000 U/ml) caused concentration -dependent relaxation of endothelium-intact aorta rings preconstricted with phenylephrine (PE,10(-6)mol/L), to(90.1+/-0.91)%, (65.1+/-5.21)%, (39.5+/-8.22)% and (35.3+/-8.27)% of pre-drug control, respectively. Removal of the endothelium inhibited the relaxation by IFN-alpha. The vasorelaxant effect of IFN-alpha (100 U/ml ) was attenuated by pretreatment with L-NAME (10(-4)mol/L), methylene blue (10(-5)mol/L) or AMG (10(-4)mol/L), to (97.2+/-5.34)%, (95.1+/-6.25)% and (93.7+/-8.82)% of the control, respectively. Pretreatment with IFN-alpha (1,000,000 U/d, i.p.) for five days markedly inhibited the endothelium-dependent relaxation of the aortic rings to acetylcholine. But the endothelium-dependent relaxation to acetylcholine was not changed by pretreatment of IFN-alpha (10,000 U/ml) with the isolated aorta rings for 2 h.</p><p><b>CONCLUSION</b>The vasorelaxation induced by IFN-alpha in rat aorta rings is endothelium-dependent and is possibly mediated by inducible nitric oxide synthase. Chronic treatment of IFN-alpha may impair the endothelium or NO-sGC pathway.</p>