15-hydroxy-11-alpha-9-alpha-(epoxymethano)prosta-5-13-dienoic-acid and Hypertension--Renovascular

To investigate the molecular mechanisms and cellular signaling pathways involved in the activation of TP receptors and the consequent induction of contractile responses in coronary arteries of renal hypertensive (2K-1C) rats.. The coronary perfusion pressure (CPP) was lower in 2K-1C rats during increased coronary flow as measured by the Langendorff technique. The coronary contraction and relaxation were evaluated by vascular reactivity studies, and the molecular mechanisms were investigated on the basis of the protein expression of TP receptors, Cav-1, eNOS, COX-1, and COX-2, as measured by Western blot. The levels of eicosanoids were determined by ELISA immunoassay and analyzed by reverse-phase HPLC coupled to electrospray ionization mass spectrometry (HPLC-MS/MS). The metabolites from NO production were evaluated by the Griess reaction. The coronary arteries of 2K-1C rats expressed COX-2 to a larger extent and TP receptors to a lesser extent than the coronary arteries of normotensive (2K) rats. Selective COX-1 and non-selective COX inhibitors reversed the reduction in the contraction induced by TP receptors in the coronary arteries of 2K-1C rats. U46619, an agonist of TP receptors, induced a contractile response that was relaxed by acetylcholine (ACh). In the coronary arteries of 2K-1C rats, this ACh-induced relaxation depended on COX. The activation of TP receptors increased the production of PGI. Activation of TP receptors increases production of PGI

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Analysis of Variance; Animals; Blood Pressure; Cardiomegaly; Chromatography, Reverse-Phase; Coronary Vessels; Cyclooxygenase 1; Cyclooxygenase 2; Disease Models, Animal; Epoprostenol; Hypertension, Renovascular; Male; Membrane Proteins; Nitric Oxide; Rats; Rats, Wistar; Receptors, Thromboxane; Spectrometry, Mass, Electrospray Ionization; Thromboxanes; Vasodilation

The endothelial nitric oxide synthase (eNOS) plays an important role in the control of the vascular tone. This work aimed to evaluate the role of an α1-adrenoceptor agonist phenylephrine (PE) on eNOS activity and downstream signaling pathway activation in normotensive (2K) and renal hypertensive (2K-1C) intact-endothelium rat aortas. Concentration-effect curves were performed for PE in intact-endothelium aortas from 2K and 2K-1C rats, in the absence of or in the presence of NOS or soluble guanylyl cyclase (sGC) inhibitor. Intact endothelium aortas were stimulated with PE in organ chambers and eNOS Ser(1177)/Thr(495) phosphorylation expression was evaluated by western blot. Nitric Oxide (NO) production was evaluated in isolated endothelial cells from 2K and 2K-1C rat aortas by flow-cytometry using NO selective fluorescent probe, DAF-2DA. The sGC activity/expression was also evaluated. PE-induced contractile response is lower in 2K-1C than in 2K intact-endothelium rat aorta. This is due to higher eNOS Ser(1177) phosphorylation in 2K-1C, which induces the eNOS overactivation. It was abolished by NOS or sGC inhibition. Phenylephrine reduces NO production in 2K as compared to the basal level, but it is not modified in 2K-1C. In PE-stimulated endothelial cells, the NO production is higher in 2K-1C than in 2K. Phenylephrine induces higher cGMP production in 2K-1C than in 2K, despite the lower expression of sGC in 2K-1C. Our results suggest that alpha1-adrenoceptor activation contributes to the increased activity of the enzyme eNOS by Ser(1177) phosphorylation in 2K-1C intact-endothelium aorta, which consequently decreases PE-induced contractile response.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Aorta; Cyclic GMP; Endothelium, Vascular; Enzyme Activation; Gene Expression Regulation, Enzymologic; Guanylate Cyclase; Hypertension, Renovascular; Male; Nitric Oxide; Nitric Oxide Synthase Type III; Phenylephrine; Phosphodiesterase Inhibitors; Phosphorylation; Proto-Oncogene Proteins c-akt; Rats; Serine; Signal Transduction; Solubility; Vasoconstriction

Actin polymerization (APM), regulated by Rho GTPases, promotes myocyte force generation. Hypoxia is known to impede postnatal disassembly of the actin cytoskeleton in pulmonary arterial (PA) myocytes. We compared basal and agonist-induced APM in myocytes from PA and descending aorta (Ao), under hypoxic and normoxic conditions. We also examined effects of thromboxane challenge on force generation and cytoskeletal assembly in resistance PA and renal arteries from neonatal swine with persistent pulmonary hypertension (PPHN) induced by 72-h normobaric hypoxia, compared with age-matched controls. Synthetic and contractile phenotype myocytes from neonatal porcine PA or Ao were grown in hypoxia (10% O(2)) or normoxia (21% O(2)) for 7 days, then challenged with 10(-6) M thromboxane mimetic U46619. F/G actin ratio was quantified by laser-scanning cytometry and by cytoskeletal fractionation. Thromboxane receptor (TP) G protein coupling was measured by immunoprecipitation and probing for Gαq, G12, or G13, RhoA activation by Rhotekin-RBD affinity precipitation, and LIM kinase (LIMK) and cofilin phosphorylation by Western blot. Isometric force to serial concentrations of U46619 was measured in muscular pulmonary and renal arteries from PPHN and control swine; APM was quantified in fixed contracted vessels. Contractile PA myocytes exhibit marked Rho-dependent APM in hypoxia, with increased active RhoA and LIMK phosphorylation. Their additional APM response to U46619 challenge is independent of RhoA, reflecting decreased TP association with G12/13 in favor of Gαq. In contrast, hypoxic contractile Ao myocytes polymerize actin modestly and depolymerize to U46619. Both basal APM and the APM response to U46619 are increased in PPHN PA. APM corresponds with increased force generation to U46619 challenge in PPHN PA but not renal arteries.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Actin Cytoskeleton; Actins; Animals; Animals, Newborn; Aorta, Thoracic; Cell Culture Techniques; Cell Hypoxia; Disease Models, Animal; Humans; Hypertension, Renovascular; Hypoxia; Infant, Newborn; Laser Scanning Cytometry; Lim Kinases; Muscle Cells; Persistent Fetal Circulation Syndrome; Phosphorylation; Pulmonary Artery; Receptors, Thromboxane; Renal Artery; rhoA GTP-Binding Protein; Swine; Thromboxanes; Vasoconstriction; Vasoconstrictor Agents

The vascular responses to angiotensin II (Ang II) in the renal circulation are increased in kidneys from rats with aortic coarctation compared with sham-operated rats. We have suggested that these differences are related to changes in mediators of the Ang II effect. The aim of this study was to investigate the role of arachidonic acid (AA) metabolites on the Ang II effect in the renal circulation of normotensive and hypertensive rats. We evaluated vascular renal reactivity in the rat isolated perfused kidney. Bolus injection of Ang II (9, 18, 36, 72 ng) increased perfusion pressure in a dose-dependent manner by 16.5+/-4, 23.5+/-4, 35.5+/-7, and 42.5+/-7 mm Hg in sham-operated rats and 50+/-6, 72+/-10, 92+/-6, and 120+/-6 mm Hg in rats with aortic coarctation. Ang II-induced vasoconstriction was prevented in hypertensive rats and potentiated in normotensive rats by the presence of indomethacin (1 microg/ml) in the perfusion solution. Furthermore, the use of the endoperoxide/thromboxane blocker (SQ29548, 1 microM) did not alter the effect of Ang II on the normotensive rats but prevented its effect in hypertensive rats. Moreover, the prostaglandin/ thromboxane (PGH2/TxA2) receptor agonist U46619 increased perfusion pressure to similar values in both kidneys from sham-operated or aortic coarctation rats. Ang II stimulated AA and prostaglandin release from isolated perfused kidneys. However, autacoid release was higher in kidneys from rats with aortic coarctation. In conclusion, we suggest that during the development of hypertension, the AA metabolism of vasoconstrictor prostaglandins is increased, and it mediates the vasoconstrictive effects of Ang II.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Anesthesia; Angiotensin II; Animals; Arachidonic Acid; Bridged Bicyclo Compounds, Heterocyclic; Dose-Response Relationship, Drug; Drug Interactions; Fatty Acids, Unsaturated; Hydrazines; Hypertension, Renovascular; Indomethacin; Kidney; Perfusion; Prostaglandins; Rats; Vasoconstrictor Agents

To investigate the nature of the arachidonic acid metabolite involved in the altered reactivity of microvessels of two-kidney, one-clip hypertensive rats and the possible contribution of this product to the elevated blood pressure levels found in two-kidney, one-clip hypertension, mesenteric arterioles either perfused in vitro or studied in vivo were used along with blood pressure determinations. The decreased response to acetylcholine observed was normalized by ridogrel, a thromboxane A2 receptor antagonist, and dazoxiben, a thromboxane A2 synthase inhibitor. The smooth muscle response to nitric oxide, tested with sodium nitroprusside, was unaltered in two-kidney, one-clip hypertensive microvessels. Neither ridogrel nor dazoxiben modified the response to this vasodilator. In contrast, the potentiated response to noradrenaline was corrected by ridogrel and dazoxiben in vitro but not in vivo. Noradrenaline and acetylcholine increased the release of thromboxane A2 from the mesenteric microvessels of two-kidney, one-clip hypertensive rats. Ridogrel and dazoxiben decreased but did not normalize the elevated blood pressure of hypertensive rats. Based on these results, we concluded that: 1) the decreased responsiveness of smooth muscle to acetylcholine resulted from an increase in thromboxane A2 formation rather than a decrease in sensitivity to nitric oxide; 2) thromboxane A2 contributes to the increased noradrenaline response in mesenteric microvessels perfused in vitro while in in vivo other blood borne vasoactive agents may also be involved since the potentiated noradrenaline response was not corrected by inhibiting thromboxane A2 synthesis or receptors; 3) in addition to thromboxane A2, another as yet unidentified factor, may contribute to the elevated blood pressure in two-kidney, one-clip hypertension.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Arterioles; Enzyme Inhibitors; Hypertension, Renovascular; Imidazoles; Male; Mesentery; Microcirculation; Nitric Oxide; Nitroprusside; Pentanoic Acids; Perfusion; Pyridines; Rats; Rats, Wistar; Receptors, Prostaglandin; Receptors, Thromboxane; Receptors, Thromboxane A2, Prostaglandin H2; Renal Circulation; Thromboxane A2; Thromboxane-A Synthase; Vascular Resistance; Vasoconstrictor Agents

To determine the influence of experimental hypertension on the structure and function of porcine coronary small arteries.. Miniature pigs underwent partial left renal artery constriction and contralateral nephrectomy. Blood pressures were recorded, using indwelling carotid artery catheters. After 4 weeks the pigs were killed, the heart was removed and subepicardial third-order branches of the left anterior descending artery were dissected and mounted in a myograph for morphological and functional assessment.. Final mean +/- SEM systolic and diastolic blood pressures were, respectively, 197 +/- 9 and 142 +/- 7 mmHg (n = 21) for the hypertensive pigs and 125 +/- 4 and 80 +/- 4 mmHg (n = 11) for the sham-operated control pigs. Hypertension was associated with significant left ventricular hypertrophy. The media thickness: lumen diameter ratio was increased significantly in hypertensive intramyocardial small arteries, caused mainly by remodelling (remodelling index 92%) rather than by medial growth. Maximal contractile responses to potassium and acetycholine were significantly depressed in the arteries from hypertensive pigs, whereas endothelium-dependent relaxation responses to bradykinin, substance P and serotonin were not significantly influenced by hypertension.. These results demonstrate that even short-term hypertension induces both structural and functional changes in left ventricular intramyocardial small arteries.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Cardiomegaly; Coronary Vessels; Dose-Response Relationship, Drug; Endothelium, Vascular; Female; Hypertension, Renovascular; Male; Prostaglandin Endoperoxides, Synthetic; Swine; Swine, Miniature; Thromboxane A2; Vasoconstriction

The present investigation contractile responses of microdissected intrarenal arcuate arteries from sham-operated rabbits and two-kidney, one clip Goldblatt hypertensive rabbits at 2 and 12 weeks after procedure. Arcuate arteries from both kidneys of the sham-operated rabbits and stenotic and nonstenotic kidneys of the Goldblatt hypertensive rabbits were studied. Mean arterial blood pressures of the sham-operated and Goldblatt hypertensive rabbits were 72 +/- 2 and 85 +/- 2, and 130 +/- 3 and 125 +/- 4 mm Hg at 2 weeks and 12 weeks, respectively. In vitro isometric contractile force measurements were made with a small-artery myograph. Responses to graded concentrations of norepinephrine were evoked in the arcuate arteries, and the maximum active force was developed and -log EC50 was determined. At 2 weeks after procedure, the maximum responses of the vessels from the left kidney of the sham-operated rabbits and those from the stenotic left kidney of the Goldblatt hypertensive rabbits did not differ. The responses of the vessels from the right kidney of the sham-operated rabbits did not differ from those of the nonstenotic right kidney of the hypertensive rabbits. A markedly depressed maximum response of the vessels from the nonstenotic kidney of the hypertensive as compared with the right kidney of the sham-operated rabbits was found at 12 weeks after procedure, whereas the vessels from the stenotic kidney of the hypertensive and the left kidney of the sham-operated rabbits exhibited almost identical maximal responses. Responses to U 46619 were similarly affected in the two groups of rabbits. Cold-induced contractile responses of the arcuate arteries from the nonstenotic kidney of the hypertensive rabbits did not differ from those of the sham-operated rabbits at the 12-week interval.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Arteries; Cold Temperature; Hypertension, Renovascular; Phosphatidylinositols; Prostaglandin Endoperoxides, Synthetic; Rabbits; Renal Circulation; Sympathomimetics; Vasoconstriction; Vasoconstrictor Agents

Vascular reactivity of the contralateral kidney of conscious Goldblatt hypertensive dogs was studied by eliciting renal blood flow (RBF) responses to intra-arterial infusions of vasoconstrictor and vasodilator agonists in control sessions and at weekly intervals postclipping. Systemic arterial blood pressure (BP) and RBF were monitored during each recording session via an implanted catheter and electromagnetic blood flow probe, respectively. BP was maximally increased within 1 wk and remained elevated for the duration of the study. The relationship between the negative percent change in RBF (-% delta RBF) and the renal arterial plasma concentration of adrenergic agonists, angiotensin II and thromboxane mimetic (U 46619), infused intra-arterially was subjected to regression analysis, and 25 and 50% effective doses (ED25 and ED50, respectively) were calculated. Vascular sensitivity to phenylephrine and norepinephrine increased within a month or more of hypertension. Vascular reactivity to angiotensin II was unchanged. In contrast to the delayed increase in renal vascular reactivity to adrenergic agonists, enhancement of the RBF responses to U 46619 was seen within 1-2 wk. In addition, beta-adrenoceptor-mediated vasodilation appeared suppressed during hypertension. Alteration in the response of the contralateral kidney to both vasoconstrictor and beta-adrenoceptor-mediated vasodilator stimuli may contribute to renal hemodynamic changes in Goldblatt hypertension.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Adrenergic beta-Agonists; Angiotensin II; Animals; Blood Pressure; Dogs; Female; Hypertension, Renovascular; Kidney; Male; Norepinephrine; Prostaglandin Endoperoxides, Synthetic; Regional Blood Flow; Renin; Vasoconstriction