介入治疗动脉导管未闭

目的　采用 Amplatzer封堵器和 Porstm ann海绵塞子封堵器方法 ,经皮穿刺动脉、静脉 ,治疗动脉导管未闭(PDA) ,并对其疗效 ,安全性进行评价。方法　 2 0例患者 ,其中男 5例 ,女 15例 ,年龄 10～ 32岁。15例行 Porstm ann法 ,5例做 Am platzer法 ,均经临床症状、体检、EKG(心电图 )、X线胸片及超声心动图检查证实为 PDA。结果　 2 0例患者手术都成功。术后即刻心前区连续性杂音消失。造影示 19例完全堵闭 ,仅 1例存在少量残余分流 ,术后发生溶血 ,经内科保守处理 96小时后超声心动图示分流消失。 2 0例病人随访 6～ 36个月未发现装置移位、再通或狭窄。结论　 Amplatzer封堵器和 Porstmann封堵器经导管介入治疗 PDA是一种安全有效的治疗方法     

Is Physiological Angiogenesis in Skeletal Muscle Regulated by Changes in Microcirculation?

Physiological angiogenesis occurs in female reproductive organs, in growing antlers as a result of long-term exposure to cold and possibly hypoxia, and due to increased activity (training) in skeletal and cardiac muscle. The common denominator is increased blood flow, which may result in increased velocity of flow and/or diameters in arterioles and capillaries, increased capillary pressure and increased capillary hematocrit. Increased velocity would lead to increased shear stress, while increased pressure and/or diameters would increase wall tension. Either of these factors may cause a disturbance of the endothelium on the luminal side of vessels. In addition, increased contractile activity during training could cause changes on the abluminal side (for example, modification of the capillary basement membrane or the extracellular matrix induced by stretch/relaxation). In order to elucidate the role of these individual factors in angiogenesis, microcirculation was studied in skeletal muscles which were exposed to: (a) increased activity by chronic electrical stimulation; (b) long-term increase in blood flow by various vasodilators; (c) long-term administration of CoCl₂ to increase hematocrit; and (d) long-term stretch, achieved by removal of agonist muscles. Capillary growth, demonstrated as an increased capillary/fiber ratio, as determined by histochemical staining and by electron microscopy, occurred in (a), (b), and (d), but not (c). Capillary proliferation, estimated by labeling index for bromodeoxyuridine of capillary-linked nuclei, occurred in (a), but not in (b). Chronic electrical stimulation resulted in an increase in the diameter of capillaries, a transient widening of arterioles, and no change in venules. Capillary hematocrit and the velocity of red blood cells (V_rbc) were also increased. Calculated shear stress and capillary wall tension were higher in stimulated muscles than in control muscles. Long-term increase in blood flow, induced by administration of the α₁-blocker prazosin, caused increased V_rbc with no change in diameters and increased only capillary shear stress. Stretched muscles had decreased blood flow, but longer sarcomeres initially caused concomitant stretch of capillaries. Increased shear stress/wall tension/stretch may initiate angiogenesis by damaging the luminal side of endothelial cells and/or their basement membrane, or by releasing growth factors or other humoral agents (prostaglandins and/or nitric oxide). Immunohistochemistry in stimulated or stretched muscles showed no evidence for expresson of mRNA for basic fibroblast growth factor (bFGF), or the growth factor itself, but a low molecular mass endothelial cell-stimulating angiogenic factor (ESAF) (77) was increased in (a), (b), and (d). The involvement of prostaglandins and nitric oxide was demonstrated by the finding of attenuated incorporation of BrdU into capillary-linked nuclei in stimulated muscles after administration of indomethacin or L-NNA. Thus, changes in the microcirculation leading to increased shear stress and/or capillary wall tension may stimulate proliferation of endothelial cells either directly, or by release of various humoral factors. However, extravascular mechanical factors have also to be taken into account.     

Structural changes in renal arterioles in Type I diabetic patients

Aims/hypothesis. We aimed to obtain data on arteriolar structure in a follow-up study of microalbuminuric diabetic patients. Methods. Kidney biopsies were obtained at baseline and after 8 years in 18 Type I (insulin-dependent) diabetic patients. Albumin excretion rate, blood pressure and HbA_1C were measured regularly, and the glomerular filtration rate (GFR) was measured at the time of the kidney biopsy. The biopsy was embedded into plastic blocks and serially sectioned with 1 μm sections. In levels 25 μm apart, afferent and efferent arteriolar profiles were identified and digitised in the electron microscope. The extra-cellular matrix as volume fraction of the media was measured, and estimates of thickness of matrix, media, endothelium and lumen were obtained. Baseline and follow-up biopsies were studied concomitantly. Results. A large increase was seen in matrix volume fraction in afferent (p = 0.0001) and in efferent arterioles (p = 0.0004). Estimated thickness of media and matrix increased, whereas endothelial cell thickness decreased, over the 8 years. There was a correlation between the parameters of diabetic glomerulopathy and arteriolar parameters in the biopsies done at 8 years, basement membrane thickness compared with afferent matrix volume fraction: r = 0.74, p = 0.0005. Also aggravation of glomerulopathy and arteriolar structure over 8 years showed positive correlation. Arteriolar parameters correlated with the albumin excretion rate (AER) and inversely with GFR. Conclusion/interpretation. The arteriolar accumulation of matrix parallels that taking place in glomeruli and shows association with functional parameters over 8 years in Type I diabetic patients with microalbuminuria. These changes are considered an important part of the structural lesions in the diabetic kidney underlying the development of diabetic nephropathy. [Diabetologia (2002) 45: ▪–▪] Received: 9 October 2001 and in revised form: 29 November 2001     

Remodeling in the microcirculation of rat skeletal muscle during chronic ischemia

OBJECTIVE: To establish the time course and extent of remodeling of terminal microcirculation in ischemic rat skeletal muscle during prolonged low flow that does not lead to inflammation. METHODS: One common iliac artery was ligated via laparotomy in adult Sprague-Dawley rats and extensor digitorum longus (EDL) muscles removed at intervals (1, 2, and 5 weeks) postsurgery. Serial frozen EDL sections were stained to show capillaries (alkaline phosphatase), cell proliferation (antibody to proliferating cell nuclear antigen [PCNA]), terminal microvessels (antibodies to alpha-smooth muscle actin (alpha-SMA) or endothelial nitric oxide synthase [eNOS]), and macrophages (antibodies to infiltrating and resident macrophages). Total muscle eNOS protein was quantified by standard Western blotting techniques. RESULTS: Capillary proliferation was very limited in ischemic EDLs, with a modest 12% increase in the capillary/fiber ratio after 5 weeks, preceded at 2 weeks by increased numbers of PCNA-positive nuclei at capillary sites. There was no muscle necrosis or evidence of inflammation, based on macrophage staining. The number of terminal microvessels that were positive for alpha-SMA and <10 microm in diameter was fewer in ischemic EDLs at all time points, whereas the number of larger positive vessels was unchanged. eNOS-positive vessels <10 microm in diameter were stained similarly throughout ischemic muscles as the controls, and showed a similar increase in vessel/fiber ratio as the capillaries. The total eNOS protein level was similar to that in controls in ischemic EDLs after 1 and 2 weeks, but was 28% lower after 5 weeks. CONCLUSIONS: Prolonged, moderate flow reduction to skeletal muscles does not necessarily lead to inflammation or extensive capillary growth. Based on eNOS staining, the terminal microcirculation remains intact, but the loss of alpha-SMA immunoreactivity may indicate remodeling involving the "deinvestment" of microvessels by smooth muscle.     

糖尿病大鼠冠状小动脉超氧阴离子产生量的观察

目的探讨糖尿病大鼠高糖状态下冠状小动脉超氧阴离子(O2-)产生量,阐明高糖状态对O2-产生的影响。方法用链脲佐菌素制备大鼠糖尿病模型,通过手术显微镜及显微手术器械分离大鼠冠状动脉,冷冻切片制备部分标本,用免疫荧光技术测定糖尿病及正常大鼠冠状动脉O2-产生量。结果糖尿病模型组大鼠冠状动脉O2-产生量与正常对照组大鼠及模型组预先加入自由基清除剂组相比明显增加;冷冻切片冠状动脉横切面荧光染色结果表明糖尿病大鼠高糖状态下血管平滑肌与内皮O2-产生均增多。结论高糖能刺激冠状小动脉产生过量的O2-,参与糖尿病状态下的氧化应激,可能与糖尿病微血管并发症密切联系。     

Hydrogen peroxide emerges as a regulator of tone in skeletal muscle arterioles during juvenile growth

OBJECTIVE: The endothelium-dependent dilation of skeletal muscle arterioles is mediated by factors that have not been identified in young rats, and partly mediated by an unidentified hyperpolarizing factor in maturing rats. This study was designed to determine if endogenous hydrogen peroxide (H2O2) contributes to this arteriolar dilation at either of these growth stages. METHODS: Gracilis muscle arterioles were isolated from rats at ages 24-26 days ("weanlings") and 46-48 days ("juveniles"). We investigated the effects of catalase treatment on the endothelium-dependent dilation of these vessels to simvastatin and acetylcholine (ACh). Catalase-sensitive 2',7'-dichlorofluorescein (DCF) fluorescence also was measured as an index of H2O2 formation, and arteriolar dilation to exogenous H2O2 was pharmacologically probed in each age group. RESULTS: Responses to simvastatin and ACh were attenuated by catalase in juvenile, but not weanling, arterioles. Juvenile, but not weanling, arterioles also displayed catalase-sensitive DCF fluorescence that was increased by ACh. Exogenous H2O2 could induce dilation in juvenile, but not weanling, arterioles. In juvenile arterioles, this dilation was abolished by the K+ channel inhibitors TEA and glibenclamide, and attenuated by NOS inhibition or endothelial removal. CONCLUSIONS: These findings suggest that endogenous H2O2 contributes to endothelium-dependent arteriolar dilation in juvenile rats, but not in younger rats, and that H2O2 acts in juvenile rats by stimulating endothelial NO release and activating smooth muscle K+ channels.     

Connexin abundance in resistance vessels from the renal microcirculation in normo‐ and hypertensive rats

The expression of connexins in renal arterioles is believed to have a profound impact on conducted responses, regulation of arteriolar tonus and renal blood flow. We have previously shown that in renal preglomerular arterioles, conducted vasomotor responses are 40% greater in spontaneously hypertensive rats (SHR) than in normotensive Sprague–Dawley (SD) rats. Because conducted vasomotor responses depend on the cell–cell communication mediated through gap junctions, we hypothesized that the increased magnitude of conducted vasomotor response in SHR is associated with an increased amount of connexins in renal arterioles. To test this hypothesis, the amount of connexin 37 (Cx37), Cx40 and Cx43 was assessed in renal arterioles from normo‐ and hypertensive rats using quantitative immunofluorescence laser confocal miscroscopy. To account for differences in genetic background, we included both normotensive Wistar–Kyoto (WKY) and SD rats in the study. In all three strains of rats, and for all three isoforms, the expression of connexins was predominantly confined to the endothelial cells. We found a significantly increased abundance (240 ± 17.6%, p<0.05) of Cx37 in arterioles from WKY compared with SD and SHR. This high abundance of Cx37 was not related to blood pressure because normotensive SD demonstrated a level of Cx37 similar to that of SHR. Additionally, we found no evidence for an increased abundance of Cx40 and Cx43 in renal arterioles of SHR when compared with normotensive counterparts.