Dataset Information

Mechanism of trypsin-induced endothelium-dependent vasorelaxation in the porcine coronary artery.

ABSTRACT: 1. To investigate the mechanism underlying the trypsin-induced endothelium-dependent relaxation, cytosolic Ca(2+) concentration ([Ca(2+)](i)) and tension development of smooth muscle were simultaneously monitored in the porcine coronary artery, and [Ca(2+)](i) of in situ endothelial cells were monitored in the porcine aortic valvular strips, using fura-2 fluorometry. 2. During the contraction induced by 30 nM U46619, a thromboxane A(2) analogue, 100 nM trypsin induced a rapid transient significant decrease in both [Ca(2+)](i) (from 67.9+/-5.1 to 15.7+/-4.4%) and tension (from 97.5+/-9.2 to 16.8+/-3.5%) of smooth muscle only in the presence of endothelium (100% level was assigned to the level obtained with the 118 mM K(+)-induced contraction). [Ca(2+)](i) and the tension thus returned to the levels prior to the application of trypsin by 5 and 10 min, respectively. 3. The initial phase of this relaxation was partly inhibited by 100 microM N(omega)-nitro-L-arginine (L-NOARG), and was completely inhibited by L-NOARG plus 40 mM K(+) or L-NOARG plus 100 nM charybdotoxin and 100 nM apamin, while the late phase of the relaxation was inhibited by L-NOARG alone. 4. Trypsin induced a transient [Ca(2+)](i) elevation in the endothelial cells mainly due to the Ca(2+) release from the intracellular stores, at the concentrations (1 - 100 nM) similar to those required to induce relaxation. 5. In conclusion, trypsin induced an elevation in [Ca(2+)](i) mainly due to Ca(2+) release in endothelial cells, and thereby caused endothelium-dependent relaxation. The early phase of relaxation was due to nitric oxide and hyperpolarizing factors, while the late phase was mainly due to nitric oxide in the porcine coronary artery.

SUBMITTER: Nakayama T

PROVIDER: S-EPMC1573010 | biostudies-other | 2001 Oct

REPOSITORIES: biostudies-other

ACCESS DATA

Similar Datasets

Project description:Gut microbiota are emerging as potential contributors to the regulation of host homeostasis. Dysbiosis of the gut microbiota associated with increased intestinal permeability facilitates the passage of endotoxins and other microbial products, including indoxyl sulfate in the circulation. Although an emerging body of evidence has suggested that indoxyl sulfate is a key substance for the development of chronic kidney disease, few studies have investigated the direct association of indoxyl sulfate with vascular function. We hypothesized that indoxyl sulfate adversely affects vascular function. Aortas isolated from male Wistar rat were examined in the presence or absence of indoxyl sulfate to assess the vascular function, including vasorelaxation and vasocontraction. Indoxyl sulfate (vs. vehicle) (1) decreased vasorelaxation induced by acetylcholine (ACh) but not by sodium nitroprusside; (2) had no significant alterations of noradrenaline-induced vasocontraction in the absence and presence of endothelium; (3) decreased adenylyl cyclase activator (forskolin)-induced vasorelaxation, while such a difference was eliminated by endothelial denudation; and (4) decreased vasorelaxations induced by calcium ionophore (A23187) and transient receptor potential vanilloid 4 agonist (GSK1016790A). The indoxyl sulfate-induced decrease in the vasorelaxations induced by ACh and A23187 increased by cell-permeant superoxide dismutase or by organic anion transporter inhibitor. However, apocynin, an inhibitor of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, had no effects on vasorelaxations induced by ACh, A23187, forskolin, and GSK1016790A in the presence of indoxyl sulfate. These results suggest that indoxyl sulfate directly affects the vascular function, particularly, endothelium-dependent vasorelaxation, and this effect may be attributable to increased oxidative stress after cell transportion via organic anion transporter, and such increased oxidative stress may not be attributable to activation of NADPH oxidase activation.

Project description:1. The mechanisms underlying the vasodilator response to urocortin are incompletely understood. The present study was designed to examine the role of endothelial nitric oxide and Ba(2+)-sensitive K(+) channels in the endothelium-dependent component of urocortin-induced relaxation in the rat left anterior descending coronary artery. 2. Urocortin induced both endothelium-dependent and -independent relaxation with respective pD(2) of 8.64+/-0.03 and 7.90+/-0.10. Removal of endothelium reduced the relaxing potency of urocortin. In rings pretreated with 10(-4) M N(G)-nitro-L-arginine methyl ester, 10(-5) M methylene blue or 10(-5) M ODQ, the urocortin-induced relaxation was similar to that observed in endothelium-denuded rings. L-Arginine (5x10(-4) M) antagonized the effect of N(G)-nitro-L-arginine methyl ester. 3. The relaxant response to urocortin was reduced in endothelium-intact rings preconstricted by 3.5x10(-2) M K(+) and abolished when extracellular K(+) was raised to 5x10(-2) M. Pretreatment with 10(-4) M BaCl(2) significantly inhibited urocortin-induced relaxation. Combined treatment with 10(-4) M BaCl(2) plus 10(-4) M N(G)-nitro-L-arginine methyl ester did not cause further inhibition. In urocortin (10(-8) M)-relaxed rings, BaCl(2) induced concentration-dependent reversal in vessel tone. Tertiapin-Q (10(-6) M) also attenuated urocortin-induced relaxation. In contrast, BaCl(2) did not alter urocortin-induced relaxation in endothelium-denuded rings. 4. In endothelium-denuded rings, hydroxylamine- and nitroprusside-induced relaxation was inhibited by 10(-4) M BaCl(2), but not by 10(-6) M tertiapin-Q. 5. The endothelium of the coronary artery was moderately stained with the antiserum against urocortin. 6. Taken together, the present results indicate that the urocortin-induced endothelium-dependent relaxation of rat coronary arteries is likely attributable to endothelial nitric oxide and subsequent activation of Ba(2+)- or tertiapin-Q-sensitive K(+) channels. The urocortin-induced endothelium-dependent relaxation appears to be mediated by cyclic GMP-dependent mechanisms.

Dataset Information

Mechanism of trypsin-induced endothelium-dependent vasorelaxation in the porcine coronary artery.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets