Drugs online research references
Hypertension. 1995 Mar;25(3):449-52.
Pressure enhances endothelin-1 release from cultured human endothelial cells.
Hishikawa K, Nakaki T, Marumo T, Suzuki H, Kato R, Saruta T.
Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan.
The effect of pure pressure without shear stress or stretch on the release of endothelin-1 was investigated. Elevation of pressure significantly enhanced endothelin-1 release from cultured human umbilical vein endothelial cells. A calcium channel blocker, nifedipine, and a putative stretch-activated channel blocker, gadolinium, did not affect the pressure-induced endothelin-1 increase. On the other hand, a phospholipase C inhibitor, 2-nitro-4-carboxyphenyl-N,N-diphenylcarbamate, and protein kinase C inhibitors, 1-5-(isoquinolinylsulfonyl)-2-methylpiperazine and chelerythrine, significantly inhibited the pressure-induced endothelin-1 increase. Moreover, pure pressure reduced basal nitric oxide release, while pretreatment with a nitric oxide synthase inhibitor, NG-monomethyl-L-arginine, had no effect on the pressure-induced endothelin-1 increase. In conclusion, our results show for the first time that pressure enhances endothelin-1 release partially through activation of phospholipase C and protein kinase.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7875771&dopt=Abstract
Am J Physiol. 1994 Feb;266(2 Pt 2):F325-41.
Ionic currents and endothelin signaling in smooth muscle cells from rat renal resistance arteries.
Gordienko DV, Clausen C, Goligorsky MS.
Department of Medicine, State University of New York at Stony Brook 11794-8152.
The repertoire of ionic channels expressed in myocytes freshly isolated from microdissected interlobar and arcuate arteries of rat kidney and their integrative behavior in response to endothelin-1 (ET-1) were studied by identification and characterization of major whole cell current components using patch-clamp technique. In renal microvascular smooth muscle cells (RMSMC) dialyzed with K(+)-containing solution, rapidly inactivating (Ito) and sustained outward K+ currents were identified. Voltage-dependent Ito was categorized as "A" current based on its kinetics, sensitivity to 4-aminopyridine (4-AP), and refractoriness to tetraethylammonium (TEA+). Ca(2+)-activated component of K+ current was completely blocked by 10 mM TEA+, whereas 5 mM 4-AP did not affect this current. Maximal Ca2+ current (ICa) recorded in Cs(+)-loaded RMSMC reached 250 pA when cells were bathed in a solution with 2.5 mM Ca2+. Two patterns of ICa differing in kinetics, voltage range of activation and inactivation, and sensitivity to nifedipine were identified as T and L currents. Ca(2+)-dependent current component showing reversal potential near Cl- current (ECl) and sensitivity to blocking action of 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid was identified as Ca(2+)-activated ECl. Activation of RMSMC with ET-1 (1-10 nM) induced elevation of [Ca2+]i and subsequent activation of Ca(2+)-activated ICl, which led to membrane depolarization sufficient to activate voltage-gated Ca2+ channels. ET-1-evoked transient reduction of ICa carried through voltage-gated Ca2+ channels was followed by augmentation of L-type ICa. ET-1-induced mobilization of intracellular Ca2+, accompanied by membrane depolarization, resulted in activation of Ca(2+)-dependent K+ channels, which can play the role of a feedback element terminating ET-1-induced membrane depolarization.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8141333&dopt=Abstract
Biochem Biophys Res Commun. 1989 Sep 15;163(2):936-43.
Functional endothelin/sarafotoxin receptors in rat heart myocytes: structure-activity relationships and receptor subtypes.
Galron R, Kloog Y, Bdolah A, Sokolovsky M.
Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel.
Functional receptors for the peptides of the endothelin (ET) and sarafotoxin (SRTX) family were characterized in newborn rat heart myocytes using human and rat endothelins (ET-1 and ET-3, respectively), SRTX-b and SRTX-c. Binding studies in intact cells and homogenates revealed significantly higher affinities of ET-1 and SRTX-b than of ET-3 and SRTX-c towards these receptors. This binding profile of ET/SRTX peptides points to their interaction with the receptor subtype designated E-S alpha. All four peptides induced time- and dose-dependent phosphoinositide hydrolysis with the following rank order of potency: ET-1 greater than SRTX-b greater than SRTX-c greater than ET-3. Thus, ET-3 which possesses an intermediate affinity toward the receptor was the least effective with regard to this response. These results confirm and extend our earlier report that the ET/SRTX peptides interact with a newly characterized receptor(s) associated with phosphoinositide metabolism and Ca2+ mobilization. The initiation of inositol phosphate formation is largely independent of extracellular Ca2+, verapamil and nifedipine, indicating that the ET/SRTX peptides are not agonists for the voltage-dependent Ca2+-channels.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2551278&dopt=Abstract
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