心率变异性指标与冠状动脉病变狭窄程度的相关性研究

目的探讨心率变异性(HRV)指标与冠状动脉病变狭窄(冠脉狭窄)程度的相关性。方法纳入本院2015年12月至2017年12月收治的冠脉狭窄患者96例,均经冠状动脉造影确诊。根据冠状动脉病变评分(Gensini积分)标准分为轻度狭窄组(n=31)、中度狭窄组(n=33)、重度狭窄组(n=32)。所有患者均接受24 h动态心电图检查,比较三组HRV指标,包括平均正常R-R间期标准差(SDNN)、每5 min R-R间期均值标准差(SDANN)、正常相邻RR间期差值均方根(r MSSD)、正常相邻R-R间期差值大于50 ms的百分比(p NN50)和低频与高频功率比值(LF/HF)。采用Pearson线性相关分析,明确HRV与冠脉狭窄程度(即Gensini积分)间的相关性。结果轻度狭窄组的SDNN、SDANN、r MSSD、p NN50高于中、重度狭窄组,且中度狭窄组各指标高于重度狭窄组,差异均有统计学意义(P0.05)。轻度狭窄组的LF/HF、Gensini积分低于中、重度狭窄组,中度狭窄组上述指标低于重度狭窄组,差异均有统计学意义(P0.05)。经Pearson线性相关分析发现SDNN、SDANN、r MSSD、p NN50与Gensini积分呈负相关(r值分别为-0.890,-0.877,-0.843和-0.802;P0.05),LF/HF与Gensini积分呈正相关(r=0.872,P0.05)。结论不同冠脉狭窄程度患者的HRV指标存在差异:冠脉狭窄程度越重,SDNN、SDANN、r MSSD、p NN50越低,LF/HF越高,反之亦然。HRV各指标均与冠脉狭窄程度有较强的相关性。     

慢性失眠对老年糖尿病患者静息心率及心率变异性的影响

目的探讨慢性失眠对老年糖尿病患者静息心率(RHR)及心率变异性(HRV)的影响。方法入选老年患者236例,分为健康对照组62例,单纯糖尿病组64例,糖尿病合并失眠组110例,其中糖尿病合并失眠组按失眠病程分为<5年组(40例),5⁹年组(38例)和≥10年组(32例)。所有患者行常规心电图及24 h心电图检查,并对RHR,HRV时域指标窦性R-R间标准差(SDNN)、窦性R-R间期标准差(SDANN)、窦性R-R间期标准差均值(SDNN index)、窦性R-R间期差值>50 ms(r MSSD)和R-R连质差异均值的平方根(PNN50),频域指标低频(LF)、高频(HF)及LF/FH进行对比分析。结果与健康对照组相比,单纯糖尿病组和糖尿病合并失眠组HRV各时域指标及频域指标LF、HF降低,RHR及LF/HF增高(P<0.05)。与单纯糖尿病组相比,糖尿病合并失眠组HRV各时域指标及频域指标LF、HF降低明显,LF/HF增高明显(P<0.05)。糖尿病合并失眠组中失眠病程59年组(38例)和≥10年组(32例)。所有患者行常规心电图及24 h心电图检查,并对RHR,HRV时域指标窦性R-R间标准差(SDNN)、窦性R-R间期标准差(SDANN)、窦性R-R间期标准差均值(SDNN index)、窦性R-R间期差值>50 ms(r MSSD)和R-R连质差异均值的平方根(PNN50),频域指标低频(LF)、高频(HF)及LF/FH进行对比分析。结果与健康对照组相比,单纯糖尿病组和糖尿病合并失眠组HRV各时域指标及频域指标LF、HF降低,RHR及LF/HF增高(P<0.05)。与单纯糖尿病组相比,糖尿病合并失眠组HRV各时域指标及频域指标LF、HF降低明显,LF/HF增高明显(P<0.05)。糖尿病合并失眠组中失眠病程5⁹年组和≥10年组的HRV各时域指标及频域指标LF、HF降低,RHR及LF/HF增高(P<0.05);失眠病程≥10年组的HRV各时域指标及频域指标LF、HF较59年组和≥10年组的HRV各时域指标及频域指标LF、HF降低,RHR及LF/HF增高(P<0.05);失眠病程≥10年组的HRV各时域指标及频域指标LF、HF较5⁹年组进一步降低,RHR及LF/HF进一步增高(P<0.05)。结论慢性失眠可加重老年糖尿病患者自主神经功能紊乱,其中失眠病程越长,糖尿病患者自主神经功能紊乱程度更明显。     

急性冠脉综合征患者心率震荡与心率变异特点及相关性分析

目的通过对急性冠脉综合征(ACS)患者心率震荡(HRT)、心率变异性(HRV)特点研究,探讨HRT与HRV在不同ACS患者中的特点及HRT与HRV间的相关性。方法ACS患者120例,不稳定型心绞痛(UAP)、ST段抬高性心肌梗死(STEMI)和非ST段抬高性心肌梗死(NSTEMI)患者各40例,选择40名健康人为对照组。所有入选者均行24h动态心电图检查,分别计算HRT指标震荡初始(TO)、震荡斜率(TS)及HRV指标SDNN、RMSSD、PNN50、HF及LF,同时分别研究TO或TS与SDNN、RMSSD、PNN50、HF及LF的相关性。结果与对照组比较,ACS组TO值升高,TS值明显降低(P0.05或P0.01);心率变异指标SDNN、RMSSD、PNN50均较对照组降低(P0.01)。ACS患者行组间比较,3组TO、TS值及RMSSD、PNN50无统计学意义(P0.05),与UAP组比较,STEMI组心率变异指标SDNN降低,两者比较有统计学意义(P0.05)。TO与SDNN、HF、LF分别呈负相关关系,其中与LF关系较为密切(r=-0.544)。TS与SDNN、RMSSD、PNN50、HF和LF分别呈正相关关系,其中与HF的相关性最强(r=0.646)。结论ACS患者心率震荡现象明显减弱,心率变异性明显降低,STEMI患者表现尤为明显;TS主要与心脏迷走神经的张力有关,TO可能与迷走和交感神经的共同调节有关。     

心得安改善短效钙拮抗剂心痛定心率变异性的研究

探讨β受体阻滞剂心得安是否可以改善短效钙拮抗剂心痛定的心率变异性(HRV)。将101例观察对象随机分为对照组(只使用心痛定,n=49)和试验组(使用心痛定和心得安,n=52),分别在服药前及服药后7～10天做24h动态心电图检测,分析HRV指标:正常RR间期的标准差(SDNN)、每5min平均RR间期的标准差(SDANN)、相邻RR之差的均方根(RMSSD)、相邻RR之差>50ms占总窦性心搏的百分数(PNN50)、低频(LF)、高频(HF)、低频和高频比值(LF/HF)。结果:对照组在治疗后心率(HR)加快,SDNN、SDANN显著降低(分别为105.2±31.8msvs126.9±32.0ms、98.9±20.1msvs107.9±19.8ms,P均<0.05),LF、LF/HF升高(分别229.3±77.1Hzvs196.1±64.8Hz、5.4±1.9vs3.8±1.8,P均<0.05),HRV降低;而试验组在治疗后心率无明显改变,SDNN、SDANN、LF、HF升高(分别为140.1±29.8msvs129.1±31.9ms、127.8±21.1msvs108.2±20.1ms、209.8±70.1Hzvs197.3±65.1Hz、148.5±48.8Hzvs123.5±41.0Hz,P均<0.05),LF/HF降低(P<0.05),治疗组HRV升高。结论:心得安能改善短效钙拮抗剂心痛定的HRV。     

特发性室性心律失常患者的心率变异性

目的探讨自主神经系统在特发性室性心律失常(IVA)发生机制中的作用。方法入选组:IVA组(n=97)和对照组(n=114例);根据电生理标测和导管消融结果将IVA组又按起源不同分为右室(RV)组(n=57)和左室(LV)组(n=40)。HRV的检测与分析建立在24 h动态心电图记录基础上,HRV分析指标包括:1时域指标:正常窦性RR间期的总体标准差(SDNN)、每5 min窦性RR间期均值标准差(SDANN)、正常连续窦性RR间期差值均方根(RMSSD)和相邻RR间期差值50 ms百分比(PNN50);2频域指标:低频谱功率(LF)、高频谱功率(HF)、低频/高频谱功率比值(LF/HF)。结果 IVA组与对照组相比较,SDNN、SDANN、RMSSD、PNN50、Ln LF及LF/HF均低于对照组。RV组与LV组相比较,RV组的SDNN与SDANN低于LV组,而LF/HF则高于LV组。结论 HRV在正常人与IVA患者之间以及左、右室不同起源的IVA患者之间存在差异性,提示自主神经系统可能参与了IVA的发生。     

苯那普利对肾性高血压大鼠心率变异的影响

目的:探讨苯那普利对肾性高血压大鼠降压同时对心率变异的影响。方法:制备肾性高血压大鼠模型,给予苯那普利治疗,分析其心率变异(HRV)的变化,并测定大鼠血浆血管紧张素Ⅱ(AngⅡ)的浓度。结果:高血压鼠血浆AngⅡ水平明显升高,心率变异时域指标中SDNN(全程记录期间所有窦性心搏R-R间期的标准差).rMSSD(相邻R-R间期差值的均方根)明显降低,频域指标中TP(总功率谱),VLF(极低频功率谱),LF(低频功率谱),HF(高频功率谱)明显降低,LF／HF(低高频比值)升高,P均<0.01;治疗后SDNN.rMSSD,TP,HF明显提高,LF／HF明显降低,P均<0.01。结论:苯那普利降压同时可改善自主神经调节功能。     

心率减速力预测老年糖尿病患者心血管事件

目的通过对老年糖尿病患者与正常人心率减速力和心率变异性的分析,探讨心率减速力的检测对于预测老年糖尿病患者心血管事件的发生变化规律。方法选取正常组:50岁~70岁无糖尿病患者100例,糖尿病组:50岁~70岁有糖尿病但未发生心血管事件者100例,全部做24h动态心电图监测,采集心率减速力(DC)、心率加速力(AC)、心率变异的低频(LF)、高频(HF)、总体标准差(SDNN)、静息心率(RHR)、平均心率(AHR)、夜间心率(NHR)进行统计分析。结果糖尿病组与正常组比:DC、AC、LF、HF、SDNN的均值均显著减低。结论糖尿病患者随着心脏自主神经功能下降,心率逐渐减低,心血管事件的发生较非糖尿病患者机率增高。     

肥厚型心肌病病人心率减速力与心率变异性相关性分析

目的分析肥厚型心肌病(HCM)病人心率减速力(DC)、连续心率减速力(DRs)、心率加速力(AC)、心率变异性(HRV),及DC与HRV的相关性,探讨其在评估自主神经功能方面的作用。方法选取2012年4月—2016年10月我院符合研究标准的HCM病人53例作为HCM组,健康者59名作为对照组。所有受检者行24h动态心电图检查,计算机自动检测DC、AC、DRs(包括DR1-DR10)及HRV各项指标,包括时域指标:RR总体标准差(SDNN)、24h每5min RR间期平均值的标准差(SDANN)、相邻RR间期差值的均方根值(rMSSD)、相邻RR间期差值50ms的百分数(pNN50);频域指标:总功率(TP)、极低频功率(vLF)、低频功率(LF)、高频功率(HF)及比值(LF/HF)。采用统计学分析DC与HRV的相关性。结果 HCM组与对照组比较,DC、AC、DR1、DR3-DR10、SDNN、SDANN、TP、vLF、LF、LF/HF差异均有统计学意义(P0.05);相关性分析显示DC与SDNN、TP、vLF、LF、HF呈正相关,具有统计学意义(P0.05)。结论 DC、DRs、AC、HRV等指标可有效评估HCM病人自主神经功能受损情况。     

心肌梗死与心肌梗死伴糖尿病患者的心率变异性分析

应用24小时全信息动态心电监测仪,分别测定单纯MI组(39例),MI合并T2DM组(20)例,正常对照组(24例)HRV的时域指标:总体标准差(SDNN),均值标准差(SDANN),差值均方的平方根(rMSSD)和爱丁堡指数(pNN50);频域指标:低频(LF)反应交感神经张力,高频(HF)反应迷走神经能力,低/高比率(LF/HF)反应交感神经与迷走神经均衡性。结果与对照组比较,单纯MI组SDNN、HF显著降低(P0.05),rMSSD、PNN50差异无显著意义。MI伴DM组与对照组比较,HRV时域指标SDNN、SDANN、PNN50显著降低,HF降低、LF/HF升高有显著意义。与单纯MI组比较,SDNN、HF差异有统计学意义,其余指标比较无显著意义。结论心肌梗死伴糖尿病患者HRV降低可能与糖尿病性神经系统损害及心肌缺血程度较单纯心肌梗死严重有关。     

苯那普利对原发性高血压患者心率变异性的影响

目的研究血管紧张素转换酶抑制剂盐酸苯那普利(Benazepril Hydrochloride)对原发性高血压患者心率变异性(Heart rate variability,HRV)的影响.方法 21例原发性轻中度高血压患者服苯那普利(10～20 mg/d,8周,n=21)前后行24小时动态心电图检查分析心率功率谱时域和频域指标.结果苯那普利使HRV时域指标SDNNI轻度降低,SDNN、 SDANN, rMSSD和频域指标HF轻度增加,频域指标TF,LF和LF/HF明显降低.结论苯那普利对原发性高血压患者降压同时,对心率变异性产生有益的作用.     

Vanadate improves cardiac function and myocardial energy metabolism in diabetic rat hearts

Vanadium mimicking the metabolic effects of insulin is known to decrease serum glucose levels and to influence glucose metabolism in diabetes mellitus. However, it is unclear whether vanadium ameliorates the metabolic disorder in diabetic hearts causing myocardial dysfunction. The purpose of this study was to assess the effects of vanadium on cardiac performance and energy metabolism in diabetic rat hearts. Four groups of Wistar rats were studied: untreated control rats (group C, n = 8). vanadate-treated rats (group V, n = 10), untreated diabetic rats (group DM, n = 9) induced by streptozotocin. and vanadate-treated diabetic rats (group DMV, n = 8). Vanadate-treated rats drank a 1.5 mM sodium orthovanadate (Na3VO4) solution during a 4 week diabetic condition. Hearts were perfused with Krebs-Henseleit buffer after the diabetic duration. After the maximum left ventricular dP/dt and cardiac efficiency were calculated, the myocardial contents of ATP and creatine phosphate (P-Cr) and myocardial energy metabolism were assessed by cytosolic phosphorylation potential. Peak positive and negative dP/dt, and cardiac efficiency decreased significantly in group DM compared with group C, while there were no significant differences between groups C and DMV. The myocardial contents of ATP (micromol/g wet heart) and P-Cr (micromol/g wet heart), and cytosolic phosphorylation potential (M(-1)) increased from 2.72 +/- 0.46. 1.45 +/- 0.58. and 3,530 +/- 1,220 in group DM to 3.88 +/- 0.76, 3.81 +/- 1.36, and 11,200 +/- 2,400 in group DMV, respectively. It is concluded that vanadium restored the production of high energy phosphates in the myocardium and improved myocardial dysfunction by regulating metabolic processes in diabetic rat hearts.     

糖尿病大鼠血浆中介素的水平变化及其对胃动力的影响

目的 观察糖尿病大鼠血浆中介素(IMD)的水平变化及其对胃动力的影响.方法 将60只雄性Wistar大鼠按照随机数字表法分为糖尿病2 w组(DM-1),正常对照2 w组(NC-1),糖尿病20 w组(DM-2),正常对照20 w组(NC-2),每组15只.糖尿病组大鼠饲喂高脂高糖饲料以诱导出胰岛素抵抗,腹腔注射小剂量链脲佐菌素(STZ,30 mg/kg)复制2型糖尿病大鼠模型.造模成功后,分别于第2周和第20周行SPECT胃排空功能测定,得出半排空时间(GET1/2)和55 min胃内核素残留率;酶联免疫法测定血浆IMD含量.结果 ①DM-1组大鼠胃排空半排时间少于NC-1组(P＜0.05);DM-2组半排时间多于NC-2组(P<0.05);DM-1组与DM-2组比较差异显著(P<0.001);NC-1组与NC-2组比较无差异.②DM-1组大鼠血浆IMD含量低于NC-1组(P<0.05);DM-2组血浆IMD含量高于NC-2组(P<0.05);DM-1组与DM-2组比较差异显著(P<0.001);NC-1组与NC-2组比较无差异.③血浆IMD水平与胃排空半排时间呈正的直线相关.结论 IMD参与了糖尿病大鼠胃动力异常的病理生理过程,可能对胃运动具有调节作用.     

舒洛地特对糖尿病大鼠尿白蛋白排泄率及肾脏转化生长因子-β1表达的影响

目的 探讨舒洛地特对链脲佐菌素诱导的糖尿病大鼠尿白蛋白排泄率及肾脏转化生长因子-β1 mRNA和蛋白表达的影响.方法 33只健康8周龄雄性SD大鼠采用随机数字表法分为健康对照组(n=11)、糖尿病组(n=11)及舒洛地特干预组(n=11).糖尿病组和舒洛地特干预组空腹10 h后一次性腹腔内注射链脲佐菌素溶液(65 mg/kg),健康对照组注射等量生理盐水.72 h后尾静脉空腹血糖>16.7 mmol/L且持续3 d视为造模成功,其中糖尿病组成模大鼠9只,舒洛地特干预组成模大鼠10只.舒洛地特干预组给予10 mg·kg-1·d-1舒洛地特灌胃,糖尿病组和健康对照组给予等量生理盐水灌胃,共12周.用药结束后次晨测定24 h尿白蛋白排泄率,留取肾脏组织作转化生长因子-β1免疫组织化学染色,应用逆转录-聚合酶链反应(RT-PCR)测定其mRNA表达水平.采用单因素方差分析及SNK或LSD检验进行统计学分析.结果 24 h尿白蛋白排泄率糖尿病组平均为363μg/min,舒洛地特干预组为151μg/min,健康对照组为26 μg/min,差异有统计学意义(F=93.93,P<0.01).糖尿病组肾脏组织转化生长因子-β1 mRNA的表达量为3.11±0.84,舒洛地特干预组为0.99±0.27,健康对照组为0.44±0.13,差异有统计学意义(F=80.43,P<0.01).肾脏组织转化生长因子-β1蛋白免疫组织化学染色在糖尿病组着色深且广泛,舒洛地特干预组较糖尿病组染色浅,与健康对照组相近.结论 舒洛地特可降低尿白蛋白排泄率,下调肾脏组织转化生长因子-β1 mRNA及蛋白的表达,从而发挥肾脏保护作用.     

糖尿病大鼠心力衰竭时心肌细胞凋亡的研究

目的探讨糖尿病大鼠心力衰竭时是否存在心肌细胞凋亡.方法建立STZ糖尿病大鼠模型,饲养12周,经心功能检测后确认为糖尿病心力衰竭的大鼠,采用TUNEL法及TEM法,检测糖尿病大鼠左室心肌的凋亡细胞.结果 糖尿病大鼠出现心功能异常并可见凋亡的心肌细胞,而对照组左室心肌组织中未见心肌细胞凋亡.结论心肌细胞凋亡与糖尿病大鼠心力衰竭密切相关.     

Power spectra of arterial pressure and heart rate in streptozotocin-induced diabetes in rats.

BACKGROUND: Chronic diabetes is associated with alterations in autonomic modulation of the cardiovascular system. Although the rat has been used extensively in studies of experimental diabetes, there have been no reports on the changes in autonomic modulation of the cardiovascular function in chronic diabetic rats. OBJECTIVE: To examine chronic diabetic rats to determine the autonomic modulation of arterial pressure and heart rate variabilities in the time and frequency domain. MATERIALS AND METHODS: Diabetes was induced in rats by a single injection of streptozotocin, and 30 min of pulsatile arterial pressure was recorded in conscious rats, 5, 10-20 days and 12-18 weeks after the streptozotocin injection. Control rats were injected with vehicle. Beat-by-beat systolic arterial pressure and heart rate were obtained from pulsatile pressure. The spectral density powers of systolic arterial pressure and heart rate were calculated using fast Fourier transformation, and integrated in low-(0.015-0.25 Hz), mid- (0.25-0.75 Hz) and high- (0.75-3.0 Hz) frequency bands. The standard deviations of systolic arterial pressure and heart rate were also calculated. RESULTS: Basal systolic arterial pressure and heart rate were reduced in diabetic animals studied 10-20 days and 12-18 weeks after the streptozotocin injection. The standard deviations of systolic arterial pressure and heart rate were also reduced in the chronically diabetic animals. Diabetes reduced low- and mid-frequency variability but not the high-frequency variability of systolic arterial pressure. The low-frequency variability, but not the mid-frequency variability, of the heart rate was also reduced, while the high-frequency variability of the heart rate was reduced in the more chronically diabetic rats. CONCLUSION: Our findings that the mid-frequency band variability of arterial pressure was reduced in diabetic patients suggest that sympathetic modulation of the cardiovascular system is impaired, corroborating other studies in such patients using this and other approaches.     

2型糖尿病对大鼠心肌缺血再灌注损伤救援激酶信号通路的影响

目的 探讨2型糖尿病(T2DM)对心肌缺血后适应(ischemic postconditioning,IPO )减轻心肌缺血再灌注损伤作用的影响及可能机制.方法　高脂饮食联合STZ诱导制成T2DM大鼠模型,将60只雄性Wistar大鼠随机分为正常大鼠缺血再灌注组(A组)、正常大鼠缺血后适应组(B组)、糖尿病大鼠后适应组(C组).3组均采用离体大鼠心脏Langendorff灌流方法　,全心停灌30 min,复灌60 min,制成心肌缺血再灌注模型.B、C组在再灌注开始前先给予再灌注10 s,全心停灌10 s,共6次循环的IPO.免疫组织化学染色及Western印迹法测定心肌磷酸化Akt,磷酸化糖原合成酶激酶(GSK-3β)的表达.结果 正常离体大鼠心肌IPO干预后磷酸化Akt及GSK-3β的表达增强;而对T2DM大鼠给予IPO处理后磷酸化Akt及GSK-3β的表达无增强,去磷酸化GSK-3β表达增强.结论 IPO对正常大鼠离体心脏缺血再灌注损伤有明确的保护作用,而对T2DM大鼠心肌缺血再灌注损伤无保护作用;其机制可能与糖尿病状态下影响再灌注损伤救援激酶信号通路,导致GSK-3β活性(去磷酸化水平)增高有关.     

Isoenzyme profiles of creatine kinase, lactate dehydrogenase, and aspartate aminotransferase in the diabetic heart: comparison with hereditary and catecholamine cardiomyopathies

STUDY OBJECTIVE--The aim was to investigate the redistribution of isoenzymes, clinically important markers of myocardial necrosis, in the diabetic heart and compare it with that investigated in other types of cardiomyopathies. DESIGN--Myocardial isoenzyme activity of creatine kinase (CK), lactate dehydrogenase (LD) and aspartate aminotransferase (AST) was measured in animals with diabetic, hereditary, and catecholamine cardiomyopathies. SUBJECTS--Diabetic rats (4 and 8 weeks after intravenous streptozotocin, n = 21), Bio 14.6 hamsters (30, 90, 160 and 240 days old, n = 29), and rats injected with isoprenaline (0.25, 0.5 and 1.0 mg.kg-1.d-1 for 3 weeks, n = 20) were used. Controls were age matched intact animals (n = 8-11). MEASUREMENTS AND MAIN RESULTS--Total CK and CK MM activity decreased in all groups. CK MB and BB decreased by 62 and 52% in diabetic rats, but increased by 40 and 33% in Bio hamsters and by 9 and 96% in isoprenaline treated rats. Thus the CK-B subunit decreased by 61% in diabetics and increased by 33 and 38% in Bio and isoprenaline groups, while the CK-M subunit decreased in all groups. Mitochondrial CK decreased in diabetic and isoprenaline groups. Total LD activity increased in diabetics and decreased in Bio. LD-H subunit increased by 21% in diabetics and decreased by 19 and 18% in Bio and isoprenaline groups. Accordingly the proportion of LD-M subunit, an index of anaerobic metabolism, decreased in diabetics and increased in Bio and isoprenaline groups. Changes in CK-M and CK-B subunits and the LD-M proportion in diabetic heart were normalised by insulin. Total AST activity decreased in diabetics because of the reduction in mitochondrial AST. CONCLUSIONS--Increased LD-M proportion and CK-B observed in Bio and isoprenaline groups may be a metabolic "compensation" to decreased myocardial perfusion and substrate. Decreased LD-M proportion and CK-B in the diabetic heart was insulin dependent and may indicate either lack of "compensation" to myocardial ischaemia or absence of ischaemia per se. Decreased myocardial CK and CK MB activity possibly causes underestimation of enzymatically assessed infarct size in the diabetic heart.     

Role of exercise training on pulpal blood flow in diabetic rats

The purpose of this study was to determine the role of exercise training on blood flow in diabetic dental pulp. Male Spraque-Dawley rats were divided into three groups of control (CON), diabetes (STZ), and diabetes with exercise-trained (STZ + Ex) groups. Diabetes was induced by intravenous injection of streptozotocin (STZ; 55 mg/kg.bw). The exercise training protocol consisted of treadmill running, 5 times/week with the velocity of 13-15 m/min for 30 min. At 12 weeks (wks) and 24 wks after the STZ injection, the laser Doppler flowmeter (Model ALF 21, USA) was used to measure pulpal blood flow (PBF) while the animals were anesthetized with sodium pentobarbital (50 mg/kg.bw). The results showed that STZ rats developed hyperglycemia, hypertriglyceridemia, higher mean arterial blood pressure, higher heart weight, body weight loss, and lower of PBF in the intact right lower incisor. Exercise training has beneficial effect on physiological characteristics of diabetic condition including triglyceride level, mean arterial blood pressure, heart rate, and heart weight. Interestingly, reduction of the PBF was restored in STZ + Ex rats. In conclusion, our observations indicate that exercise training can prevent the reduction in PBF of STZ-induced diabetic rats.     

Preservation of heart function in diabetic rats by the combined effects of muscle cell implantation and insulin therapy

BACKGROUND: Diabetic cardiomyopathy is a common cause of heart failure in diabetic patients, but current treatments do not directly improve ventricular function. Cell transplantation can prevent cardiac dilatation after injury, and may also prevent congestive heart failure in diabetic cardiomyopathy. AIM: This study evaluated the functional effects of smooth muscle cells (SMCs) implanted into the myocardium of insulin- and non insulin-treated diabetic rats. METHODS: Four weeks after streptozotocin infusion, adult Wistar rats were implanted with BrdU-labelled SMCs or culture media (N=12/group). Six rats in each group were also treated with insulin. Echocardiograms were performed at 0, 4 and 8 weeks after streptozotocin injection, and histology and heart function were evaluated at 4 weeks after implantation. RESULTS: Blood glucose levels decreased after insulin treatment. Among cell-injected rats, histology indicated that those that did not receive insulin retained fewer surviving BrdU+ SMCs, and a smaller volume of myocardial tissue positive for alpha-smooth muscle actin. Cardiac function was preserved in the insulin-treated groups relative to those that did not receive insulin. Among insulin-treated rats, the cell-injected group functioned better than the media-injected group. CONCLUSIONS: Diabetic cardiomyopathy is partially treatable with insulin; however, a combination of SMC transplantation and insulin treatment produced the best functional result. Cell transplantation may prevent the progression of diabetic cardiomyopathy in patients whose glucose levels are controlled with insulin.     

Alterations in the baroreceptor reflex control of heart rate in streptozotocin diabetic rats

Baroreflex control of heart rate was studied in conscious diabetic rats at 12, 24 and 48 weeks after the induction of diabetes with streptozotocin. Baseline blood pressure (mean arterial blood pressure) of diabetic rats was significantly lower at 12 weeks after the induction of diabetes when compared to age-matched control rats. However, at 24 and 48 weeks of diabetes, no difference in blood pressure was observed between diabetic and age-matched control rats. In contrast, bradycardia (prolongation of pulse interval) was a consistent feature of diabetic rats at all time points (12, 24, and 48 weeks). To assess parasympathetic control of heart rate, baroreceptor sensitivity was determined by infusing phenylephrine. Baroreflexes in diabetic rats were changed from an increased sensitivity at 12 and 24 weeks to decreased sensitivity at 48 weeks after the induction of diabetes. This suggests that alterations in baroreflex sensitivity might depend upon the length of time the animals were exposed to the diabetes. Insulin treatment in diabetic animals reversed hypotension, bradycardia and altered baroreflex sensitivity observed in 12-week diabetic rats. Non-diabetic rats, in which the development of diabetes was prevented by pretreatment with 3-0-methylglucose before streptozotocin injection, or rats which did not develop diabetes after streptozotocin injection showed a similar baseline blood pressure, heart rate and baroreflex sensitivity to those of age-matched control rats (12, 24 and 48 weeks). This data suggests that changes in blood pressure, heart rate and baroreflex sensitivity are due to the diabetic state, not to streptozotocin toxicity.