Search

Endothelin A (ET A ) receptor blockade has prevented vascular remodeling in aldosterone and salt-induced hypertension. To evaluate effects of the ET A receptor antagonist, BMS 182874, compared with the aldosterone antagonist, spironolactone, on vascular remodeling in aldosterone-infused rats not exposed to a high salt diet, Sprague-Dawley rats were infused subcutaneously with aldosterone (0.75 μg/h) and treated with BMS 182874 (40 mg · kg −1 · d −1 ), spironolactone, or hydralazine (both 25 mg · kg −1 · d −1 ) while receiving a normal salt diet for 6 weeks. Aldosterone increased systolic BP ( P P P P A receptors. Endothelin blockade may exert beneficial effects on vascular remodeling, fibrosis, oxidative stress, and adhesion molecule expression in aldosterone-induced hypertension.

Cerebrovascular abnormalities, in endothelium and smooth muscle compartments, occur in the course of cerebral ischemia–reperfusion as evidenced by the impairment of endothelium-dependent relaxation and decrease in potassium inward rectifier density in occluded middle cerebral arteries (MCAs). The authors investigated whether a delayed vascular protection occurred in a model of brain ischemic tolerance. A low dose of lipopolysaccharide (0.3 mg/kg) administered 72 h before MCA occlusion induced a significant decrease in infarct volume. In parallel to this delayed neuroprotective effect, lipopolysaccharide prevented the ischemia–reperfusion–induced impairment of endothelium relaxation. In addition, lipopolysaccharide prevented the postischemic alteration of potassium inward rectifier–dependent smooth muscle relaxation as well as the decrease in potassium inward rectifier density measured by patch-clamp in dissociated vascular smooth muscle cells originated from the occluded MCA. These results suggest that during brain ischemic tolerance, lipopolysaccharide is able to induce both a delayed neuroprotective and vasculoprotective effect.

To assess the effects of the angiotensin-converting enzyme (ACE) inhibitor (ACEI) perindopril on prolonged endothelial cell dysfunction in a rabbit endotoxic model. Randomized, controlled, interventional trial. University animal laboratory. A total of 65 male New Zealand White rabbits, randomly assigned to one of eight groups. Endotoxic shock was induced by a single lipopolysaccharide (LPS, serotype O55:B5) bolus (0.5 mg.kg−1, i.v., Escherichia coli endotoxin). Coagulation factors and expression of monocyte tissue factor (TF) were determined by functional assay. Endothelium-dependent vascular relaxation was assessed by in vitro vascular reactivity. Immunohistochemical staining (CD31) was performed to assess endothelial injury of the abdominal aorta. These parameters were studied 5 days (D5) after the onset of endotoxic shock. Rabbits were randomized to receive perindopril (1 mg kg−1 day−1 orally) alone, or with N G -nitro-L-arginine methyl ester (L-NAME; 15 mg kg−1 day−1 orally), or L-NAME alone initiated 7 days before the onset of endotoxic shock and maintained for 5 days afterward. Perindopril prevented altered endothelium-dependent relaxation to acetylcholine induced by LPS injection (Emax=75.6±3.7 vs 42.3±9.4% in LPS group, p

In a previous retrospective study, long-term treatment of essential hypertensive patients with a slow-release calcium channel blocker resulted in normal resistance artery structure and endothelial function, which did not occur with a beta-blocker. In the present prospective study, 19 previously untreated essential hypertensive patients (aged 47 +/- 2 years, 75% male) were treated for 1 year in a double-blind randomized study with the long-acting calcium channel blocker amlodipine or the beta-blocker atenolol. Resistance arteries (lumen diameter, 150 to 350 microm) dissected from gluteal subcutaneous biopsies were studied on a pressurized myograph. Blood pressure (BP) control (129 +/- 2/85 +/- 2 mm Hg) was identical in both groups for the last 6 months of the study. After 1 year of treatment with amlodipine, the media-to-lumen ratio (M/L) of resistance arteries decreased from 7.89% +/- 0.40% to 6.81% +/- 0.41% (P < .05). Acetylcholine-induced endothelium-dependent relaxation tended to improve from 84.3% +/- 5.5% to 90.5% +/- 4.8% (P = .06), whereas sodium nitroprusside-induced relaxation was unchanged in the patients treated with amlodipine. In the beta-blocker-treated group there was no significant change in M/L or acetylcholine-induced relaxation. In conclusion, treatment with the calcium channel blocker amlodipine corrected altered resistance artery structure and tended to improve endothelial function in essential hypertensive patients, whereas similar good control of BP with the beta-blocker atenolol did not. Whether the vascular protective effect of amlodipine will result in improved outcomes in hypertension remains to be demonstrated.

The purposes of this study were to investigate the role of nitric oxide (NO), nitric oxide synthase (NOS), and 70 kDa heat shock protein in brain ischemic tolerance induced by ischemic preconditioning and lipopolysaccharide. Focal cerebral ischemia was induced in rats by intraluminal middle cerebral artery occlusion. Infarct volume was significantly reduced (1) in rats subjected to 3 min ischemia 72 h prior to 60 min ischemia; (2) in rats administered lipopolysaccharide (0.5 mg/kg; i.p.) 72 h prior to 60 min ischemia compared with controls. The beneficial effect of ischemic preconditioning was unchanged despite prior administration of nitro-L-arginine methyl ester (L-NAME), a NOS inhibitor. Conversely, the protective effect of lipopolysaccharide was nullified by L-NAME. Using immunohistochemical techniques, we observed that (1) ischemic preconditioning but not lipopolysaccharide induces the expression of 70 kDa heat shock protein in cerebral cortex and (2) lipopolysaccharide induces early increased expression of endothelial NOS in cerebral blood vessels. The results suggest that (1) endothelium-derived NO plays a role of a trigger in the brain tolerance induced by lipopolysaccharide, and (2) 70 kDa heat shock protein is involved in the protection afforded by ischemic preconditioning but not by lipopolysaccharide.

Delayed effect on vascular reactivity of isolated aorta was studied after injection of a single low dose of lipopolysaccharide (0.5 mg/kg i.p.). The maximal vascular effect was observed 72 h after lipopolysaccharide administration with an increase in maximal endothelium-dependent relaxing response to acetylcholine and parallelly a decrease in contractile response to phenylephrine. The change in contractile response was nullified by endothelium removal as well by in vitro aortic rings incubation with Nω-monomethyl- l -arginine but not with indomethacin. A low dose of lipopolysaccharide induces a delayed enhanced nitric oxide-mediated vascular relaxation which could contribute to its delayed anti-ischemic properties in ischemic tolerance phenomenon.

34 Left ventricular remodeling in hypertension is associated with cardiac interstitial and perivascular collagen deposition. The vasopeptidase inhibitor omapatrilat improves left ventricular remodeling in experimental heart failure. We hypothesized that omapatrilat would induce a regression of ventricular and vascular fibrosis in hypertension. We therefore investigated the effect of vasopeptidase inhibition on collagen deposition in heart and aorta of stroke prone spontaneously hypertensive rats (SHRSP). Ten-week old SHRSP were treated orally for 10 weeks with omapatrilat (40mg/kg/d). Collagen fibers in heart and descending thoracic aorta were stained with Sirius red. Collagen density was defined as the ratio of the area stained by Sirius red to the area of the studied field. After 10 weeks, systolic blood pressure was significantly (P3 μm/mm section, respectively, P