Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0406810 (NAME)
 13,345 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The hypothesis that the endothelium-derived relaxing factor/nitric oxide (EDNO) activity is elevated in chronic hypoxic pulmonary hypertension (CH-PHT) was tested using isolated Krebs-albumin-perfused rat lungs. Concentration of the EDNO decomposition products (NOx) in the lungs' effluent was measured by a modified chemiluminescence assay. The functional significance of basal EDNO production was studied by measuring the vasoconstrictor response to an EDNO synthesis inhibitor, N omega-nitro-L-arginine methyl ester (L-NAME). Reactivity to the endothelium-dependent vasodilator substance P and to exogenous NO was also studied. More NOx was found in effluent from CH-PHT (22.3 +/- 9.8 nM) than control (0.4 +/- 3.9 nM) lungs. The L-NAME-induced vasoconstriction was greater in CH-PHT than in control rats. The sensitivity, but not the maximal vasodilation, to exogenous NO was elevated in CH-PHT. The substance P-induced vasodilation was potentiated in CH-PHT compared with control rats and blocked by L-NAME in both groups. We conclude that basal and agonist-stimulated pulmonary EDNO activity is enhanced in this model of CH-PHT. The EDNO synthesis may play a counterregulatory role in CH-PHT.
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PMID:Increased endothelium-derived NO in hypertensive pulmonary circulation of chronically hypoxic rats. 751 87

The endothelins (ET) are potent 21-amino-acid vasoconstrictor peptides produced in many different tissues, particularly in the endothelium of blood vessels. ET-1 is the main endothelin secreted by the endothelium, and acts in a paracrine or autocrine fashion on blood vessels by interacting with ETA or ETB receptors on smooth muscle to stimulate contraction or on ETB receptors on endothelial cells to induce the release of vasorelaxants (nitric oxide and prostacyclin). Production of ET-1 is enhanced in several experimental models of hypertension in the rat, such as sodium-sensitive forms, e.g. deoxycorticosterone acetate (DOCA)-salt hypertensive, DOCA-salt-treated spontaneously hypertensive rats (SHR) and Dahl salt-sensitive rats, as well as other models such as stroke-prone SHR, angiotensin II-infused rats and fructose-fed rats, and possibly 1-K 1C Goldblatt hypertensive rats. In contrast, SHR, 2-K 1C Goldblatt hypertensive rats and nitric oxide-deficient (L-NAME-treated) hypertensive rats do not exhibit an ET-1 component. Endothelin dependency is manifested by excessive vascular growth, particularly in small arteries, and blood pressure lowering and regression of vascular growth after treatment with endothelin antagonists. The latter may be combined ETA/ETB or selective ETA antagonists, of which several are orally active and already in clinical development. In humans, endothelin-dependent vascular tone has been shown in studies of forearm blood flow. Enhanced expression of ET-1 mRNA has been demonstrated in the endothelium of small arteries of patients with moderate to severe hypertension. In a 4-week trial the combined ETA/ETB antagonist bosentan reduced the blood pressure of essential hypertensive patients equally to enalapril. Bosentan improved hemodynamics in patients with heart failure in acute and 2-week-long studies. Endothelin antagonists also offer promise in a rapidly fatal condition, primary pulmonary hypertension. Thus, the endothelin system appears to be involved in different forms of cardiovascular disease in experimental animals and humans, and its interruption offers great promise as a new therapeutic intervention in hypertension, heart failure and other diseases.
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PMID:Endothelin and endothelin antagonists in hypertension. 988 74

Appetite suppressants, such as dexfenfluramine (dex), are associated with primary pulmonary hypertension, valvular heart disease, and systemic vascular complications, such as coronary, cerebral, or mesenteric ischemia. These drugs suppress appetite by enhancing release and inhibiting reuptake of serotonin in the central nervous system. The effects of dex on the systemic circulation have not been studied. K(+) channels regulate vascular tone in most vascular beds. We hypothesized that dex is a systemic vasoconstrictor acting primarily by inhibiting K(+) channels, independent of effects on serotonin. The effects of clinically relevant concentrations of dex (10(-6) to 10(-4) M) on outward K(+) current and membrane potential were studied with whole-cell patch clamping in freshly isolated smooth muscle cells from rat renal, carotid, and basilar arteries. Tone was measured in tissue baths. Blood pressure, cardiac output, and left ventricular end diastolic pressure were assessed in open- and closed-chest anesthetized rats. At 10(-4) M, dex inhibits outward K(+) current (50%) and increases membrane potential (by >35 mV), an effect comparable with 4-aminopyridine (5 mM). Furthermore, dex constricts rings and acutely elevates systemic pressure (+17 +/- 3 mm Hg) and systemic vascular resistance in the presence of ketanserin. Dex vasoconstriction is dose-dependent (threshold dose 10(-6) M; 156 microg/ml) and enhanced in L-NAME-fed rats. We conclude that dex causes acute systemic vasoconstriction, at least in part by inhibition of voltage-gated K(+) channels, independent of effects on serotonin. To our knowledge, this is the first time that a commonly prescribed drug with voltage-gated K(+) channel-blocking properties is shown to have significant hemodynamic effects in vivo.
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PMID:Dexfenfluramine elevates systemic blood pressure by inhibiting potassium currents in vascular smooth muscle cells. 1056 35

Amfepramone (diethylpropion) is an appetite-suppressant drug used for the treatment of overweight and obesity. It has been suggested that the systemic and central activity of amfepramone produces cardiovascular effects such as transient ischemic attacks and primary pulmonary hypertension. However, it is not known whether amfepramone produces immediate vascular effects when applied in vitro to rat aortic rings and, if so, what mechanisms may be involved. We analyzed the effect of amfepramone on phenylephrine-precontracted rat aortic rings with or without endothelium and the influence of inhibitors or blockers on this effect. Amfepramone produced a concentration-dependent vasorelaxation in phenylephrine-precontracted rat aortic rings that was not affected by the vehicle, atropine, 4-AP, glibenclamide, indomethacin, clotrimazole, or cycloheximide. The vasorelaxant effect of amfepramone was significantly attenuated by NG-nitro-L-arginine methyl ester (L-NAME) and tetraethylammonium (TEA), and was blocked by removal of the vascular endothelium. These results suggest that amfepramone had a direct vasorelaxant effect on phenylephrine-precontracted rat aortic rings, and that inhibition of endothelial nitric oxide synthase and the opening of Ca2+-activated K+ channels were involved in this effect.
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PMID:Mechanisms involved in the vasorelaxant effects produced by the acute application of amfepramone in vitro to rat aortic rings. 2583 Dec