摘要:

Significant structural and functional changes in smooth muscle cells (SMCs) of microvessels (diameter 30 to 300 μm) occur in hypertension. However, in microvessels of hypertensive patients, the differentiation pattern of SMCs underlying such changes remains undefined. To analyze the differentiation pattern of SMCs (adult, postnatal, or fetal), 49 muscle biopsies (rectus abdominis) were analyzed: 16 from children (aged 11 months to 11 years), 15 from normotensive adults (aged 55 to 74 years), 18 from hypertensive adults (aged 55 to 74 years). Transverse cryosections of specimens were studied by immunocytochemistry using monoclonal antibodies SM-E7 and NM-F6, which recognize smooth muscle myosin heavy chain (MyHC) and Apla1-like nonmuscle MyHC, respectively. The total number of microvessels was assessed via SM-E7 staining. The number of NM-F6 positive (fetal-type SMC) or negative (adult-type SMC) microvessels was assessed. The number of microvessels per area unit was considerably lower (P< 0.0005) in normotensive adults (0.22±0.17) than in children (0.98±0.61). Even more significant reduction was found in hypertensive adults compared with control adults (P= 0.013) and children (P< 0.0005). The qualitative immunocytochemistry analysis by NM-F6 revealed 2 differentiation patterns of the media layer of microvessels: positive or negative. In hypertensive subjects, the percentage of microvessels positive to NM-F6 was 49.8±35.6%, close to that found in children (50.6±12.6%), whereas in normotensive subjects it was significantly lower (24.4±21.1%). The following conclusions were drawn. (1) The medial layer of microvessels is heterogeneous in terms of SMC differentiation. (2) In hypertension, a prevalence of fetal-type SMCs takes place in microvessels, resembling that of children. Compared with children, a rarefaction of microvessels is present in normotensive adults that is even more remarkable in hypertensive adults.

ISSN:0194-911X    

出版商:OVID    

年代:2004

数据来源: OVID

摘要:

In addition to the modulation of vascular tone, angiotensin II (Ang II) has growth factor–like effects in vascular tissue. The mechanisms whereby Ang II mediates these trophic actions are incompletely understood but are thought to include effects on systemic blood pressure, stimulation of transforming growth factor-β (TGF-β) expression, and transactivation of growth factor receptor kinases. To investigate the role of platelet-derived growth factor receptor (PDGFR) transactivation in mediating the growth factor–like effects of Ang II we administered Ang II (200 ng/kg per minute) or saline to male Sprague-Dawley rats by osmotic minipump for 12 days and treated with imatinib mesylate, an inhibitor of the PDGFR tyrosine kinase. In addition to systolic blood pressure elevation, Ang II infusion led to increased vascular weight, media:lumen ratio, matrix expansion, and overexpression of TGF-β mRNA in mesenteric arteries. Without affecting blood pressure or PDGF ligand expression, imatinib attenuated the changes in vessel morphology but further increased TGF-β mRNA. Western blot analysis of mesenteric arterial tissue demonstrated the presence of the β- but not the &agr;-isoform of PDGFR. Phosphorylation of PDGFR-β was increased by Ang II in vascular smooth muscle cells, and this was inhibited by imatinib. The findings of attenuation of vascular hypertrophy and matrix deposition by imatinib indicate that transactivation of the PDGFR in vivo contributes to the growth factor–like effects of Ang II, independent of its hemodynamic effects or its ability to induce TGF-β gene expression.

ISSN:0194-911X    

出版商:OVID    

年代:2004

数据来源: OVID

摘要:

Therapeutic angiogenesis using angiogenic growth factors is expected to be a new treatment for patients with critical limb ischemia (CLI). Because hepatocyte growth factor (HGF) has potent angiogenic activity, we investigated the safety and efficiency of HGF plasmid DNA in patients with CLI as a prospective open-labeled clinical trial. Intramuscular injection of naked HGF plasmid DNA was performed in ischemic limbs of 6 CLI patients with arteriosclerosis obliterans (n= 3) or Buerger disease (n= 3) graded as Fontaine III or IV. The primary end points were safety and improvement of ischemic symptoms at 12 weeks after transfection. Severe complications and adverse effects caused by gene transfer were not detected in any patients. Of particular importance, no apparent edema was observed in any patient throughout the trial. In addition, serum HGF concentration was not changed throughout the therapy period in all patients. In contrast, a reduction of pain scale of more than 1 cm in visual analog pain scale was observed in 5 of 6 patients. Increase in ankle pressure index more than 0.1 was observed in 5 of 5 patients. The long diameter of 8 of 11 ischemic ulcers in 4 patients was reduced > 25%. Intramuscular injection of naked HGF plasmid is safe, feasible, and can achieve successful improvement of ischemic limbs. Although the present data are conducted to demonstrate the safety as phase I/early phase IIa, the initial clinical outcome with HGF gene transfer seems to indicate usefulness as sole therapy for CLI.

ISSN:0194-911X    

出版商:OVID    

年代:2004

数据来源: OVID

摘要:

We examined the influence of interactions between CO and 20-hydroxyeicosatetraenoic acid (20-HETE) on vascular reactivity to phenylephrine and vasopressin. Renal interlobar arteries incubated in Krebs buffer released CO at a rate that is decreased (from 125.0±15.2 to 46.3±8.8 pmol/mg protein per hour,P<0.05) by the heme oxygenase inhibitor chromium mesoporphyrin (CrMP; 30 μmol/L). The level of 20-HETE in vessels was not affected by CrMP (74.3±6.1 versus 72.5±16.2 pmol/mg protein), but was decreased (P<0.05) by CO (1 μmol/L; 33.2±7.9 pmol/mg protein) or the cytochrome P450 – 4A inhibitorN-methylsulfonyl-12,12-dibromododec-11-enamide (DDMS; 30 μmol/L; 11.4±3.3 pmol/mg protein). Phenylephrine elicited development of isometric tension in vascular rings mounted on a wire-myograph (EC50, 0.29±0.02 μmol/L; Rmax, 3.78±0.19 mN/mm). The sensitivity to phenylephrine was decreased (P<0.05) by CO (1 μmol/L; EC50, 0.60±0.04 μmol/L) or DDMS (EC50, 0.71±0.12 μmol/L) and increased (P<0.05) by 20-HETE (10 μmol/L; EC50, 0.08±0.02 μmol/L) or CrMP (EC50, 0.11±0.02 μmol/L). Notably, neither CO nor CrMP changed the sensitivity to phenylephrine in vessels treated with DDMS. Refractoriness to CO and CrMP in such a setting was eliminated by inclusion of 20-HETE (1 μmol/L) in the bathing buffer. The aforementioned interventions affected the vascular reactivity to vasopressin in a similar manner. These data indicate that the reactivity of renal arteries to phenylephrine and vasopressin is reciprocally influenced by CO and 20-HETE of vascular origin and that CO desensitizes the vascular smooth muscle to constrictor agonists by interfering with the sensitizing influence of 20-HETE.

ISSN:0194-911X    

出版商:OVID    

年代:2004

数据来源: OVID

摘要:

Endothelial nitric oxide synthase (eNOS) plays an important role in maintaining blood pressure homeostasis and vascular integrity. Natural dietary flavoniods are thought to protect against cardiovascular diseases by acting as antioxidants and vasodilatants. This study examined the effect of cyanidin-3-glucoside (Cy3G), a typical anthocyanin pigment, on eNOS expression. Treatment of bovine artery endothelial cells (BAECs) with Cy3G for 8 hours of enhanced eNOS protein expression in a dose- and time-dependent manner was determined by Western blot analysis. Longer incubation (12, 16, and 24 hours) of BAECs with 0.1 μmol/L of Cy3G caused a further increase in eNOS expression, and subsequently Cy3G also significantly increased nitric oxide output 2-fold (24 hours). Furthermore, Cy3G stimulated the phosphorylation of Src and extracellular signal-regulated kinase 1/2 (ERK1/2) in a time-dependent manner. An Src kinase inhibitor, pp2, and MEK inhibitor, PD98059, blocked the ERK1/2 phosphorylation and eNOS expression. Transfection with dominant-negative Src cDNA also inhibited the eNOS expression stimulated by Cy3G. In addition, stimulation with Cy3G for 30 minutes resulted in a phosphorylation of Sp1 that was blocked by PD98059. Cy3G enhanced the binding activity of the transcription factor Sp1 to the GC box in the proximal eNOS promoter of BAECs, as revealed by chromatin immunoprecipitation assay. The present study demonstrated that Cy3G induced eNOS expression and escalated NO production via an Src-ERK1/2-Sp1 signaling pathway in vascular endothelial cells. Increased eNOS expression may help to ameliorate endothelial dysfunction, harmonize blood pressure, and prevent atherosclerosis as long-term beneficial effects of flavoniods.

ISSN:0194-911X    

出版商:OVID    

年代:2004

数据来源: OVID

摘要:

Distal nephron renin may provide a possible pathway for angiotensin (Ang) I generation from proximally delivered angiotensinogen. To examine the effects of Ang II on distal nephron renin, we compared renin protein and mRNA expression in control and Ang II–infused rats. Kidneys from sham (n= 9) and Ang II–infused (80 ng/kg per minute, 13 days, n= 10) Sprague-Dawley rats were processed by immunohistochemistry, Western blot, reverse transcriptase–polymerase chain reaction (RT-PCR), and quantitative real-time RT-PCR. Ang II infusion increased systolic blood pressure (181±4 versus 115±5 mm Hg) and suppressed plasma and kidney cortex renin activity. Renin immunoreactivity was suppressed in juxtaglomerular apparatus (JGA) cells in Ang II–infused rats compared with sham (0.1±0.1 versus 1.0±0.1 relative ratio) but increased in distal nephron segments (6.4±1.4 versus 1.0±0.1 cortex; 2.5±0.3 versus 1.0±0.2 medulla). Tubular renin immunostaining was apically distributed in principal cells colocalizing with aquaporin-2 in connecting tubules and cortical and medullary collecting ducts. Renin protein levels were decreased in the kidney cortex of Ang II–infused rats compared with that of sham (0.4±0.2 versus 1.0±0.4) rats but higher in the kidney medulla (1.2±0.4 versus 1.0±0.1). In kidney medulla, RT-PCR and quantitative real-time PCR showed similar levels of renin transcript in both groups. In summary, the detection of renin mRNA in the renal medulla, which is devoid of JGA, indicates local synthesis rather than an uptake of JGA renin. In contrast to the inhibitory effect of Ang II on JGA renin, Ang II infusion stimulates renin protein expression in collecting ducts and maintains renin transcriptional levels in the medulla, which may contribute to the increased intrarenal Ang II levels in Ang II–dependent hypertension.

ISSN:0194-911X    

出版商:OVID    

年代:2004

数据来源: OVID

摘要:

Cyclooxygenase-2 (COX-2) is constitutively expressed in a subset of thick ascending limb cells in the cortex and medulla and increases when the renin-angiotensin and kallikrein-kinin systems are activated. Although the contribution of angiotensin II to the regulation of COX-2 is known, the effects of bradykinin on COX-2 expression have not been determined in this nephron segment. We evaluated expression of B2 bradykinin receptors in thick ascending limb cells containing COX-2 and the effect of bradykinin on COX-2 expression in primary cultured medullary thick ascending cells. The presence of B2 receptors was studied in renal sections by immunohistochemistry with antibodies against B2, COX-2, and Tamm-Horsfall glycoprotein. B2 receptors were detected on the apical and basolateral portion of the thick ascending cells. These cells also contained COX-2, suggesting that COX-2 expression may be regulated via B2 receptor. Incubation of cultured medullary thick ascending cells with bradykinin (10−7to 10−5mol/L) induced a significant increase on COX-2 protein expression. Maximal expression of COX-2 was observed 4 hours after exposure to bradykinin (10−7mol/L), effect abolished by a B2 receptor antagonist (HOE-140; 10−6mol/L). ProstaglandinE2 production increased when these cells were challenged with bradykinin for 4 hours, indicating that COX-2 was enzymatically active. We have demonstrated (1) the presence of B2 receptors in thick ascending limb cells expressing COX-2 and (2) the stimulatory effect of bradykinin on COX-2 protein expression, via B2 receptors, in cultured medullary thick ascending cells. We suggest that bradykinin can affect ion transport in the thick ascending limb via a COX-2–mediated mechanism.

ISSN:0194-911X    

出版商:OVID    

年代:2004

数据来源: OVID

摘要:

We have recently shown that systemic administration of a superoxide dismutase mimetic, tempol, resulted in decreases in mean arterial pressure and heart rate along with a reduction in renal sympathetic nerve activity (RSNA). It has also been shown that these parameters are significantly increased by systemic administration of a superoxide dismutase inhibitor, diethyldithio-carbamic (DETC), indicating a potential role of reactive oxygen species in the regulation of RSNA. In this study, we examined the effects of local administrations of 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (tempol) and DETC on RSNA in anesthetized rats. Either tempol or DETC was directly administered onto the renal sympathetic nerves located between the electrode and ganglion. Local application of tempol (10 μL, 0.17 to 1.7 mol/L, n=6) resulted in dose-dependent decreases in integrated RSNA (by −81±6% at 1.7 mol/L) without alterations in mean arterial pressure and heart rate. In contrast, DETC (10 μL, 0.17 to 1.7 mol/L, n=6) increased RSNA dose-dependently. The responses of RSNA to tempol and DETC were significantly greater in spontaneously hypertensive rats than in normotensive rats (n=6, respectively). Local application of sodium nitroprusside (1 mmol/L) orNG-nitro-L-arginine methyl ester (0.11 mol/L) altered neither basal RSNA nor tempol-induced reductions in RSNA (n=6 and 5, respectively). A voltage-gated potassium channel blocker, 4-aminopyridine (0.1 mol/L), significantly decreased basal RSNA (by −81±1%) and completely prevented DETC-induced increases in RSNA (n=5). These results suggest that reactive oxygen species play a role in the regulation of peripheral sympathetic nerve activity, and that at least part of this mechanism is mediated through voltage-gated potassium channels.

ISSN:0194-911X    

出版商:OVID    

年代:2004

数据来源: OVID

ISSN:0194-911X    

出版商:OVID    

年代:2004

数据来源: OVID