Effects of volatile inhalational anaesthetic agents on isolated bovine cardiac myofibrillar ATPase

Volatile general anaesthetic agents exert negative inotropic effects on the heart during anaesthesia. Inhibition by anaesthetics of the myofibrillar ATPase responsible for energy transduction during cardiac contraction has been suggested as the primary site of these effects. In this study we have examined the actions of three anaesthetics with differing cardiac depressant potencies (enflurane, isoflurane and halothane) on the activity of isolated myofibrillar ATPase. The most powerful in vivo cardiac depressant, enflurane, was without effect on the ATPase but halothane and isoflurane were inhibitory to the enzyme.     

红细胞膜ATP酶活性变化与糖尿病并发症的关系

目的 探讨红细胞胞膜ＡＴＰ酶（ＡＴＰａｓｅ）活性变化与糖尿工发症之间的关系。方法 将９７例糖尿病患者分为三组：Ａ组（无并发症）３７例,Ｂ组（并发酮症酸中毒）１５例,Ｃ组（慢性血管并发症）４５例。红细胞膜Ｎａ＋－Ｋ＝－ＡＴＰａｓｅ活性（红细胞膜ＡＴＰａｓｅ活性）分别用改良的Ｈａｎａｈａｎ法和Ｌｕｔｈｒａ法进行检测,并设４９例健康乾为对照组。结果 与对照组比较,各组糖尿病患工细胞膜ＡＴＰａｓｅ活性均明     

Myosin phosphorylation decreases the ATPase activity of cardiac myofibrils

Our previous work showed that myosin phosphorylation decreased the ATPase activity of skeletal muscle myofibrils that were lightly fixed with glutaraldehyde. The fixation process prevented sarcomere shortening and destruction of the ordered filament array upon the addition of ATP. We have now extended these results to myofibrils prepared from hearts of rabbits, dogs and rats. Myofibrils were phosphorylated by incubation with myosin light chain kinase, calmodulin and either ATP-gamma s or ATP, for 15 minutes at 25 degrees C. The extent of myosin light chain phosphorylation was 50% to 80%. The ATPase activity of unphosphorylated myofibrils was not altered by reaction with 0.01% glutaraldehyde for 5 minutes at 0 degrees C, and the ATPase activity of unfixed myofibrils was not changed by phosphorylation. However, phosphorylation decreased the ATPase activity of fixed myofibrils by 50%. The effect on myocardial myofibrillar ATPase activity of phosphorylation was similar in the three animal species. These results suggest that in both skeletal and cardiac muscle, myosin phosphorylation decreases the rate of cross-bridge cycling resulting in decreased energy expenditure. It also appears that the effect of myosin light chain phosphorylation on ATPase activity requires an ordered myofilament structure.     

Association of diabetic neuropathy with Na/K ATPase gene polymorphism

Summary Diabetes mellitus induces a decrease in Na/K ATpase activity in man and animals, and this decrease plays a role in the development of diabetic neuropathy. Na/K ATPase is encoded by various genes, of which the ATP1 A1 gene is expressed predominantly in peripheral nerves and in erythrocytes. To investigate whether a polymorphism in the Na/K ATPase genes could explain the predisposition of some patients with insulin-dependent diabetes mellitus (IDDM) to develop polyneuropathy, a restriction fragment length polymorphism (RFLP) of the ATP1 A1 gene was studied together with erythrocyte Na/K ATPase activity in 81 Caucasian patients with more than 10 years' duration of IDDM. Associations with diabetic neuropathy, retinopathy and nephropathy were sought. Digestion of the first intron of the ATP1 A1 gene by the Bgl II restriction enzyme revealed a dimorphic allelism. Frequency of the restricted allele was 0.18 in this selected series (however, it was 0.10 in representative samples of IDDM patients and of normal subjects in our area). Mean erythrocyte Na/K ATPase activity was lower in diabetic patients than in 42 control subjects (292 ± 10, vs 402 ± 13 nmol Pi · mg protein^{− 1}· h^{− 1}, p < 0.0001) and was not related to HbA_1c value or to diabetes duration. It was lower in the group of the 28 patients bearing the restricted allele (241 ± 10 vs 319 ± 11 nmol Pi · mg protein^{− 1}· h^{− 1}, p < 0.0001). Neuropathy was absent in 50 patients, mild in 15 and severe in 16. When classified accordingly the three groups of patients did not differ with respect to sex, age and duration of diabetes. The respective frequency of the restricted allele among the groups was 10, 73 and 81 %, (p < 0.0001) and mean erythrocyte Na/K ATPase activity was respectively: 322 ± 10.7 nmol Pi · mg protein^{− 1}· h^{− 1}, 268 ± 15 and 229 ± 17, (p < 0.001). A borderline association between renal status or retinal status and repartition of polymorphism and a borderline correlation between renal status and Na/K ATPase activity were found, but significance disappeared after checking for the presence or absence of neuropathy. IDDM patients bearing the ATP1 A1 variant detected by Bgl II RFLP are much more frequently affected by neuropathy (relative risk 6.5, with 95 % CI 3.3–13). Identification of this risk factor may help to prevent this complication. It is suggested that the restricted allele is in linkage disequilibrium with a genomic mutation allowing diabetes to induce a greater impairment of Na/K ATPase activity which could in turn favour the development of neuropathy. [Diabetologia (1997) 40: 506–511] Received: 26 August 1996 and in revised form: 28 January 1997     

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.     

The effect of short term normothermic global ischemia and acidosis on cardiac myofibrillar Ca2+-Mg2+ ATPase activity

There is now good evidence to indicate the onset of myocardial ischemia is accompanied by a decline in intracellular pH which parallels the decrease in tension development. The component of the excitation--contraction coupling system which is responsible for the loss in tension development has not been determined although the contractile proteins are a likely candidate since the calcium sensitivity of tension development and of myofibrillar ATPase are both inhibited by a decrease in pH. However, these studies have utilized normal tissues and the effects of pH compounded with ischemia have not been determined. It is plausible to suggest that there may occur ischemic damage to the excitation--contraction coupling system which would depress function in a manner distinct from that incurred by acidosis. Toya-Oka and Ross have demonstrated a loss in regulatory proteins during regional ischemia, suggesting an effect of ischemia independent of pH. We recently demonstrated, in sarcoplasmic reticulum isolated from ischemic myocardium, a defect in function which could not be accounted for solely on the decrease in pH. It was, therefore, the purpose of this study to determine the effects of decreasing pH on cardiac myofibrillar ATPase activity isolated from hearts which had been subjected to short-term, global normothermic ischemia. This design permits us to answer the following questions: Is there a decrease in myofibrillar ATPase activity in the canine heart following 30 min of normothermic global ischemia? Does acidosis play a contributory role in any observed depression of myofibrillar ATPase activity during ischemia? and Does the ischemic process, independent of acidosis, produce a further depression of myofibrillar ATPase activity?     

氟伐他汀对糖尿病大鼠早期心肌病变的作用

目的探讨氟伐他汀对糖尿病大鼠早期心肌病变的作用。方法研究对象为链脲佐菌素诱导的SD大鼠糖尿病模型,氟伐他汀(2mg·kg-1·d-1)治疗组、糖尿病对照组和正常组各10只,实验第6周末进行血糖(BG)、总胆固醇(TC)、三酰甘油(TG)、高密度脂蛋白胆固醇(HDL-C)、脂蛋白(a)[Lp(a)]测定及大鼠左心室前壁心肌标本的光镜HE染色和透射电镜检查。结果 治疗组与糖尿病组比较,TC、TG及Lp(a)降低,HDL-C升高(P<0.05),血糖差异无显著性(P>0.05),光镜和电镜下病理改变明显减轻。结论 氟伐他汀对糖尿病大鼠心肌细胞及微血管内皮有保护作用,提示可能对糖尿病性心肌病的治疗有重要意义。     

Cardiac stem cells and myocardial disease

Recent data indicate that the heart is a self-renewing organ and contains a pool of progenitor cells (PCs). According to the new paradigm, this resident population of multipotent undifferentiated cells gives rise to myocytes, endothelial cells, smooth muscle cells and fibroblasts. Understanding the function of cardiac PCs is critical for the implementation of these cells in the treatment of the diseased human heart. However, cardiac repair is an extremely complex phenomenon. Efficient myocardial regeneration requires restoration of segmental and focal areas of myocardial scarring, replacement of damaged coronary arteries, arterioles and capillaries, and substitution of hypertrophied poorly contracting myocytes with smaller better functioning parenchymal cells. To achieve these goals, the acquisition of a more profound knowledge of the biology of cardiac PCs cells and their fate following pathologic insults represents an essential need.     

Na/K ATP酶活性及其ATP1A1基因多态性与2型糖尿病周围神经病变的相关性

目的研究大连地区汉族人Na／KATP酶活性及ATP1A1基因多态性与2型糖尿病（T2DM）周围神经病变（DPN）的关系。方法用聚合酶链反应-限制性片段长度多态性方法对大连地区的106例T2DM患者和45例正常对照者（NC）的ATP1A1基因进行扩增，对其基因多态性进行研究，并用比色法测定其红细胞的Na／KATP酶活性。结果与NC组相比，T2DM组红细胞Na／KATP酶活性降低，在伴有DPN组，Na／KATP酶活性的降低更为明显。在T2DM患者中，有DPN组与无DPN组相比，基因型分布差异有统计学意义（P〈0．05）。T2DM患者携带有限制性等位基因A与非携带者Na／KATP酶活性的差异有统计学意义（P〈0．05）。结论Na／KATP酶活性的降低在DPN的发病中起重要作用，Na／KATP酶的基因ATP1A1多态性与T2DM患者发生DPN相关。T2DM携带有限制性等位基因A的患者DPN的发生率低于非携带者。     

益母草注射液对糖尿病心肌病大鼠心肌细胞凋亡和增殖活性的作用研究

目的探讨中药益母草注射液(LHS)对链脲佐霉素(STZ)制备的糖尿病心肌病(DCM)大鼠心肌细胞凋亡和增殖活性的作用。方法2004年3月至2004年9月于汕头大学医学院第二附属医院内分泌科建立STZ诱导DCM的大鼠模型,将实验大鼠随机分为未治疗组、LHS治疗组和正常对照组,16周龄时处死,观察心肌细胞的凋亡百分数(TUNEL法)、Fas、FasL、Bax、Bcl-2、增殖细胞核抗原(PCNA)的表达(免疫组化法)、心肌细胞超微结构的改变(电镜)。结果与DCM组相比,DCM给药组大鼠心肌肌节对位仅见少部分错位,肌原纤维无溶解,线粒体结构完整;心肌细胞中促凋亡因子Fas、FasL和Bax的表达降低,抑制凋亡的Bcl-2/Bax比值增加,心肌细胞凋亡百分数降低,差异均有显著性(P<0·05);PCNA阳性细胞数增多,差异有显著性(P<0·05)。结论LHS治疗后,心肌细胞凋亡比未治疗组明显减少,而增殖活性明显增强,LHS能有效防治大鼠DCM,改善超微结构的异常。     

High-fat diet in low-dose-streptozotocin-treated heminephrectomized rats induces all features of human type 2 diabetic nephropathy: a new rat model of diabetic nephropathy

Background and aimWe have developed a new rat model that mimics the natural course of diabetic nephropathy seen in type 2 diabetes.MethodsNine days after intravenous injection of streptozotocin (STZ) (40 mg/kg) or vehicle to 8-week-old male Sprague–Dawley rats, the animals’ right kidneys were surgically removed. Two weeks after surgery, the STZ-injected rats were fed on either a high-fat (ST + HF) or a normal (ST) diet, while the vehicle-injected rats were fed on the high-fat diet (HF).ResultsBaseline biochemical markers did not differ between the three groups. Only the ST + HF group showed a significant increase in plasma glucose levels after 15 weeks, and simultaneously plasma insulin levels started to decrease, followed by an increase in plasma total cholesterol and triglyceride levels at 25 weeks and slightly later by an increase in blood pressure. In the ST + HF group, significant microalbuminuria was detected at 15 weeks followed by overt proteinuria, both of which were absent in the other two groups. Also in ST + HF, the creatinine clearance rate increased until week 15, and then gradually decreased. Histologically, ST + HF rats showed mesangial expansion at week 25, and diffuse glomerular sclerosis at the end of the experiments.ConclusionThe chronological changes in biochemical, physiological and histological markers in ST + HF rats are reminiscent of human type 2 diabetes and nephropathy. Our new model of type 2 diabetic nephropathy should help us to understand the pathophysiology of the disease and serve to explore measures to prevent and treat diabetic nephropathy.     

益母草注射液对糖尿病心肌病大鼠心肌细胞凋亡和增殖活性的作用研究

目的 探讨中药益母草注射液（LHS）对链脲佐霉素（STZ）制备的糖尿病心肌病（DCM）大鼠心肌细胞凋亡和增殖活性的作用。方法 2004年3月至2004年9月于汕头大学医学院第二附属医院内分泌科建立STZ诱导DCM的大鼠模型，将实验大鼠随机分为未治疗组、LHS治疗组和正常对照组。16周龄时处死。观察心肌细胞的凋亡百分数（TUNEL法）、Fas、FasL、Bax、Bcl-2、增殖细胞核抗原（PCNA）的表达（免疫组化法）、心肌细胞超微结构的改变（电镜）。结果 与DCM组相比。DCM给药组大鼠心肌肌节对位仅见少部分错位，肌原纤维无溶解，线粒体结构完整；心肌细胞中促凋亡因子Fas、FasL和Bax的表达降低，抑制凋亡的Bcl-2／Bax比值增加，心肌细胞凋亡百分数降低，差异均有显著性（P〈0．05）；PCNA阳性细胞数增多．差异有显著性（P〈0．05）。结论 LHS治疗后，心肌细胞凋亡比未治疗组明显减少．而增殖活性明显增强．LHS能有效防治大鼠DCM．改善超微结构的异常。     

贝前列腺素钠对糖尿病大鼠肾脏保护作用研究

目的 观察贝前列腺素钠（Beraprost Sodium,BPS）对糖尿病肾病大鼠肾脏功能及形态学方面的影响.方法 将30只SD大鼠随机分为正常对照组（NC）,糖尿病组（DM）,BPS治疗组（BPS）.STZ腹腔注射建模成功后,BPS组给予贝前列腺素钠0.6mg·kg-1·d-1灌胃,其余饲养条件三组皆同.灌胃12w结束时检测大鼠血糖、24h尿量、肾重体重比（KW/BW）、24 h尿白蛋白（UA1b/2A h）和肌酐清除率（Ccr）,并观察3组大鼠肾脏光镜及电镜下病理表现.结果 DM组血糖、尿量、KW/BW、UA1b/24 h和Ccr水平均较NC组升高（均P〈0.01）,BPS组除血糖外各项指标较DM组降低（均P〈0.01）;在光镜及电镜下观察到BPS组病理变化均较DM组有明显改善.结论 贝前列腺素钠对糖尿病大鼠肾脏具有保护作用.     

Calcium signaling in endocardial and epicardial ventricular myocytes from streptozotocin-induced diabetic rats

Aims/IntroductionAbnormalities in Ca²⁺ signaling have a key role in hemodynamic dysfunction in diabetic heart. The purpose of this study was to explore the effects of streptozotocin (STZ)‐induced diabetes on Ca²⁺ signaling in epicardial (EPI) and endocardial (ENDO) cells of the left ventricle after 5–6 months of STZ injection.Materials and MethodsWhole‐cell patch clamp was used to measure the L‐type Ca²⁺ channel (LTCC) and Na⁺/Ca²⁺ exchanger currents. Fluorescence photometry techniques were used to measure intracellular free Ca²⁺ concentration.ResultsAlthough the LTCC current was not significantly altered, the amplitude of Ca²⁺ transients increased significantly in EPI‐STZ and ENDO‐STZ compared with controls. Time to peak LTCC current, time to peak Ca²⁺ transient, time to half decay of LTCC current and time to half decay of Ca²⁺ transients were not significantly changed in EPI‐STZ and ENDO‐STZ myocytes compared with controls. The Na⁺/Ca²⁺ exchanger current was significantly smaller in EPI‐STZ and in ENDO‐STZ compared with controls.ConclusionsSTZ‐induced diabetes resulted in an increase in amplitude of Ca²⁺ transients in EPI and ENDO myocytes that was independent of the LTCC current. Such an effect can be attributed, at least in part, to the dysfunction of the Na⁺/Ca²⁺ exchanger. Additional studies are warranted to improve our understanding of the regional impact of diabetes on Ca²⁺ signaling, which will facilitate the discovery of new targeted treatments for diabetic cardiomyopathy.     

Decreased osteoblast activity in spontaneously diabetic rats

Diabetes in both humans and rats is accompanied by low bone formation, which is presumably caused by serum-borne factors. To explore its pathogenesis, we carried out experiments in diabetic and nondiabetic BB rats, using plasma osteocalcin concentrations (OC) as a marker for osteoblast activity. In nondiabetic rats, the iv infusion of glucose (30%, 4 d) did not change OC; sc insulin infusion (4 U/d, 14 d) reduced OC by 27% (p<0.01). In diabetic rats, OC were decreased from the first day of glycosuria (71±5% of paired controls), declining exponentially to 24±3% after 5 wk. Insulin infusion (1,2, and 3 U/d, 14 d) produced gradual restoration of OC. OC were better correlated with insulin-like growth factor-I (IGF-I) than with insulin levels in these experiments. OC were dramatically increased 4 d after adrenalectomy (ADX) in all diabetic rats (73±8 vs 22±4 μg/L before ADX;p<0.001), but not if corticosterone was administered. Ligand blotting of IGF binding proteins showed a marked decrease in two bands (44–49 and 32–35 kDa) 10–14 d after diabetes onset; the density of these bands was increased, but not normalized after ADX. Thus, decreased osteoblast activity is present from the onset of diabetes, is dependent on endogenous corticosterone, and cannot be reproduced by hyperglycemia in nondiabetic rats.     

Erythrocyte Na/K ATPase activity and diabetes: relationship with C-peptide level

Summary Erythrocyte Na/K ATPase activity is decreased in Type I diabetic patients; for Type II diabetic patients, literature data are controversial. Therefore, we have compared this enzymatic activity in 81 patients with Type I diabetes mellitus, 87 with Type II diabetes mellitus and 75 control subjects. Mean erythrocyte Na/K ATPase activity was lower in the Type I diabetic patients (285 ± 8 nmol Pi · mg protein^–1· h^–1) than in the control subjects (395 ± 9 nmol Pi · mg protein^–1· h^–1) whereas that of the Type II diabetic patients did not differ from that of control subjects. Sex, age, body mass index, and HbA_{1 c} levels did not influence erythrocyte Na/K ATPase activity. The 25 Type II diabetic patients treated with insulin, however, had lower Na/K ATPase activity than the 62 on oral treatment (264 ± 18 vs 364 ± 16 nmol Pi · mg protein^–1· h^–1, p < 0.001) but similar to that of Type I diabetic patients. Among the Type II diabetic patients, stepwise regression analysis showed that fasting C-peptide level was the only factor independently correlated with Na/K ATPase activity; it explained 23 % of its variance. In fact, in the insulin-treated patients, those with almost total endogenous insulin deficiency (C-peptide < 0.2 nmol · l^–1) had the lower Na/K ATPase activity (181 ± 21 vs 334 ± 17 nmol Pi · mg protein^–1· h^–1, p < 0.0001). The biological effects of treatment with C-peptide have recently led to the suggestion that this peptide could have a physiological role through the same signalling pathway as insulin, involving G-protein and calcium phosphatase and thus restoring Na/K ATPase activity. The relationship we describe between endogenous C-peptide and this activity is a strong argument for this physiological role. [Diabetologia (1998) 41: 1080–1084] Received: 6 November 1997 and in final revised form: 10 April 1998     

非胰岛素依赖型糖尿病微量白蛋白尿患者红细胞膜ATPases活力的变化

测定非胰岛素依赖型糖尿病(NIDDM)微量白蛋白尿患者20例及NIDDM无微量白蛋白尿患者20例和正常人20例红细胞膜ATPases活力。结果NIDDM微量白蛋白尿患者Na~+-K+ATPase,Ca~(2+)+ATPase活力明显低于正常人(P分别<0.05及0.001),Mg~(2+)ATPase活力无明显改变(P>0.05).NIDDM无微量白蛋白尿患者Ca~(2+)ATPase活力也低于正常人(P<0.01),但不及微量白蛋白尿组明显;无白蛋白尿组Na~+-K~+ATPase活力虽有下降,但P>0.05,Mg~(2+)ATPese活力无明显变化(P>0.05).     

曲美他嗪对老年糖尿病心肌病慢性心力衰竭患者心功能的影响

目的研究曲美他嗪对老年糖尿病心肌病（diabetic cardiomyopathy,DCM）慢性心力衰竭患者心功能的影响。方法DCM慢性充血性心力衰竭患者41例,其中男21例,女20例,年龄65～75岁,平均年龄（71．3±4．7）岁,随机分为对照组和治疗组。对照组给予标准药物治疗,治疗组在标准药物治疗基础上给予曲美他嗪治疗。观察两组治疗前、治疗后1年的纽约心脏病学会（NYHA）心功能分级、左室射血分数（LVEF）、6分钟步行距离（6MWD）和血浆脑利钠肽（BNPo结果两组治疗后NYHA心功能分级、LVEF、6MWD、BNP均较治疗前有明显改善,差异有统计学意义（P〈0．05o治疗组NYHA心功能分级（2．1±0．3）,对照组（2．5±0．3）,P〈0．05差异有统计学意义。治疗组LVEF为（51．1±4．5）％,对照组LVEF为（43．1±5．5）％,P〈0．05差异有统计学意义。治疗组6MWD为（364．1±21．6）m,对照组6MWD为（280．0±22．4）m,P〈0．05差异有统计学意义。治疗组BNP为（113．0±22．4）ng／mL,对照组BNP为（221．6±26．4）ng／mL,P〈0．05差异有统计学意义。结论曲美他嗪能改善老年DCM慢性心力衰竭患者心功能。     

钒酸盐纠正了糖尿病大鼠心肌组织内活化的DAG—PKC信息传导

目的 探讨糖尿病大鼠心肌细胞内传导与心功能降低的关系。方法 检测糖尿病大鼠心肌二酰基甘油含量,蛋白激酶活性和心功能变化及胃饲钒酸钠的影响。结果 糖尿病大鼠心肌ＤＡＧ含量和胞膜ＰＫＣ活性显著升高,心功能显著降低,胃饲ＳＶ后明显改善。结论ＤＡＧ－ＰＫＣ通路激活是形成糖尿病心肌病的一个重要发病机制。