BACKGROUNDHemorrhagic shock-induced changes in vascular reactivity appear organ-specific. In the present study, we examined the hypothesis that vascular reactivity induced by septic shock similarly displays organ-specific differences and is regulated by inducible nitric oxide synthase (iNOS) and endothelin-1 (ET-1).METHODSEndotoxic shock was induced in rabbits by administration of lipopolysaccharide (LPS) (1 mg/kg), and organ specificity of vascular reactivity of superior mesenteric artery (SMA), celiac artery (CA), and left renal artery (LRA) as well as the potential involvement of iNOS and ET-1 examined.RESULTSVascular reactivity of SMA, CA, and LRA was increased at the early stages and decreased at the late stages after LPS administration. Superior mesenteric artery showed the greatest decrease in vascular reactivity in response to norepinephrine (NE) (34.9%) and acetylcholine (Ach; 32.3%), followed by LRA (NE, 33.7%; Ach, 30.5%) and CA (NE, 16.2%), whereas the relaxation reactivity of CA in response to Ach was increased to 159%. The mRNA and protein levels of iNOS and ET-1 in SMA, CA, and LRA were not affected at the early stages of endotoxic shock after LPS administration but significantly increased at the late stages. Expression levels were higher in SMA than CA and LRA and negatively correlated with the decrease in vascular reactivity. The iNOS and ET-1 inhibitors, aminoguanidine (20 mg/kg) and PD-142893 (0.02 mg/kg), respectively, induced significant improvements in vascular reactivity and organ perfusion and stabilized the hemodynamic parameters in rabbits subjected to endotoxic shock.CONCLUSIONChanges in vascular reactivity during endotoxic shock are organ-specific. Differential expression patterns of iNOS and ET-1 in different blood vessels contribute to the organ specificity of vascular reactivity.LEVEL OF EVIDENCETherapeutic study, level II.

01 Sep 2017·Journal of Cellular PhysiologyQ2 · BIOLOGY

The Role of Calcium‐Sensing Receptors in Endothelin‐1‐Dependent Effects on Adult Rat Ventricular Cardiomyocytes: Possible Contribution to Adaptive Myocardial Hypertrophy

Q2 · BIOLOGY

Article

Author: Arens, Christoph ; Schreckenberg, Rolf ; Schlüter, Klaus‐Dieter ; Dyukova, Elena ; Sitdikova, Guzel

Nitric oxide (NO)‐deficiency as it occurs during endothelial dysfunction activates the endothelin‐1 (ET‐1) system and increases the expression of receptor activity modifying protein (RAMP)‐1 that acts as a chaperon for calcium‐sensing receptors (CaR) that have recently been identified to improve cardiac function. Here, we hypothesized that ET‐1 increases the cardiac expression of CaR and thereby induces an adaptive type of hypertrophy. Expressions of RAMP‐1, endothelin receptors, and CaR were analyzed by RT‐PCR in left ventricular tissues of L‐NAME‐treated rats. Effects of ET‐1 on CaR expression and cell function (load free cell shortening) were analyzed in adult rat ventricular cardiomyocytes. siRNA directed against CaR and RAMP‐1 was used to investigate a causal relationship. PD142893 and BQ788 were used to dissect the contribution of ETB1, ETB2, and ETA receptors. Non‐specific NO synthase inhibition with L‐Nitro arginine methyl ester (L‐NAME) caused a cardiac upregulation of ETB receptors and CaR suggesting a paracrine effect of ET‐1 on cardiomyocytes. Indeed, ET‐1 induced the expression of CaR in cultured cardiomyocytes. Under these conditions, cardiomyocytes increased cell size (hypertrophy) but maintained normal function. Inhibition of ETA and ETB1 receptors led to ET‐1‐dependent reduction in cell shortening and attenuated up‐regulation of CaR. Down‐regulation of RAMP‐1 reduced CaR responsiveness. In conclusion, ET‐1 causes an adaptive type of hypertrophy by up‐regulation of CaR in cardiomyocytes via ETA and/or ETB1 receptors. J. Cell. Physiol. 232: 2508–2518, 2017. © 2016 Wiley Periodicals, Inc.

01 Oct 2012·Life SciencesQ3 · MEDICINE

Defining the affinity and receptor sub-type selectivity of four classes of endothelin antagonists in clinically relevant human cardiovascular tissues

Q3 · MEDICINE

Article

Author: Janet J. Maguire ; Rhoda E. Kuc ; Anthony P. Davenport

AIMSWe have compared the endothelin receptor subtype affinity (K(D)) and selectivity of four structural classes of antagonists (peptide, sulphonamide-based, carboxylic acid-based, myceric acid-based) in human cardiovascular tissues to determine whether these are predicted by values reported for human cloned receptors. Additionally, affinities (K(B)) for these antagonists, determined in ET-1-mediated vasoconstriction assays in human blood vessels, were used to identify discrepancies between K(B) and K(D) determined in the same tissues.MAIN METHODSCompetition binding experiments were carried out in sections of human left ventricle, coronary artery and homogenates of saphenous vein to determine K(D) values for structurally different ET(A)-selective (FR139317, BMS 182874, S97-139, sitaxentan, ambrisentan) and mixed (PD142893, Ro462005, bosentan, L-749329, SB209670) antagonists. Schild-derived values of antagonist affinity were obtained in vascular functional studies.KEY FINDINGSWhen compared with previously reported data in human cloned endothelin receptors, those antagonists reported to be ET(A)-selective exhibited even greater ET(A) selectivity in human ventricle (BMS 182874, sitaxentan, ambrisentan) that expressed both receptor subtypes. Those antagonists reported to have <100 fold selectivity in cloned receptors (PD142893, Ro-462005, bosentan, SB209670, L-749329) did not distinguish between receptor subtypes in human left ventricle. For antagonists where we determined affinity in vascular functional and binding assays (Ro462005, bosentan, BMS 182874, L-749329, SB209670) there was no correlation between the degree of discrepancy in K(B) and K(D) and structural class.SIGNIFICANCEFor an antagonist to retain ET(A)-selectivity in vivo it may be necessary to identify those compounds that have at least 1000 fold ET(A):ET(B) selectivity in in vitro assays.

100 Deals associated with PD-142893

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Indication	Highest Phase	Country/Location	Organization	Date
Hypertension	Discovery	US	Pfizer Inc.	-

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