Glibenclamide improves postischemic recovery of myocardial contractile function in trained and sedentary rats.

In this study, we sought to determine whether there was any evidence for the idea that cardiac ATP-sensitive K+ (K(ATP)) channels play a role in the training-induced increase in the resistance of the heart to ischemia-reperfusion (I/R) injury. To do so, the effects of training and an K(ATP) channel blocker, glibenclamide (Glib), on the recovery of left ventricular (LV) contractile function after 45 min of ischemia and 45 min of reperfusion were examined. Female Sprague-Dawley rats were sedentary (Sed; n = 18) or were trained (Tr; n = 17) for >20 wk by treadmill running, and the hearts from these animals used in a Langendorff-perfused isovolumic LV preparation to assess contractile function. A significant increase in the amount of 72-kDa class of heat shock protein was observed in hearts isolated from Tr rats. The I/R protocol elicited significant and substantial decrements in LV developed pressure (LVDP), minimum pressure (MP), rate of pressure development, and rate of pressure decline and elevations in myocardial Ca(2+) content in both Sed and Tr hearts. In addition, I/R elicited a significant increase in LV diastolic stiffness in Sed, but not Tr, hearts. When administered in the perfusate, Glib (1 microM) elicited a normalization of all indexes of LV contractile function and reductions in myocardial Ca(2+) content in both Sed and Tr hearts. Training increased the functional sensitivity of the heart to Glib because LVDP and MP values normalized more quickly with Glib treatment in the Tr than the Sed group. The increased sensitivity of Tr hearts to Glib is a novel finding that may implicate a role for cardiac K(ATP) channels in the training-induced protection of the heart from I/R injury.     

Hyperbaric oxygen inhibits neutrophil infiltration and reduces postischemic brain injury in rats

Reversible occlusion of the middle cerebral artery (MCA) was used to test hypothesis that hyperbaric oxygen inhibits the neutrophile infiltration into the ischemic brain thus reducing the brain injury. Treatment with hyperbaric oxygen prior to ischemia or during MCA occlusion significantly reduced neutrophile infiltration, motor disorders, and cerebral infarction volume.     

Preserved postischemic heart function in sucrose-fed type 2 diabetic OLETF rats

Cardiovascular disease is one of the most important causes of morbidity and mortality in diabetes mellitus, but there has been controversy over functional impairment of diabetic hearts and their tolerance to ischemia. We studied ischemic heart function in type 2 diabetic rats with different degrees of hyperglycemia and its relationship with cardiac norepinephrine release. Otsuka Long-Evans Tokushima Fatty rats (OLETF) and age-matched Long-Evans Tokushima Otsuka normal rats (LETO) were used. One group of OLETF rats was given 30% sucrose in drinking water (OLETF-S). Hearts were isolated and perfused in a working heart preparation and subjected to 30 min ischemia followed by 40 min reperfusion at age of 12 months. Hemodynamics and coronary norepinephrine overflow were examined. Fasting plasma glucose in OLETF increased markedly at 12 months and sucrose administration exacerbated hyperglycemia in diabetic rats (LETO 6.6 +/- 0.5, OLETF 8.3 +/- 0.7, OLETF-S 15.0 +/- 1.7 mmol/L, P < 0.01). Basic cardiac output in OLETF was decreased as compared with LETO and OLETF-S (LETO 29.4 +/- 2.5, OLETF 24.0 +/- 2.4, OLETF-S 27.0 +/- 0.9 ml/min/g, P < 0.05) and remained very low after ischemia, while in OLETF-S it was well preserved (OLETF 4.2 +/- 2.1, OLETF-S 13.7 +/- 2.6 ml/min/g, P < 0.01). Correspondently, cardiac norepinephrine released during ischemia and reperfusion was lower in OLETF-S (OLETF 2.3 +/- 1.0, OLETF-S 0.7 +/- 0.1 pmol/ml, P < 0.01). Thus, OLETF hearts were more vulnerable to ischemia but sucrose feeding rendered their hearts resistant to ischemia. Less norepinephrine release may play a role in preventing postischemic functional deterioration in sucrose-fed diabetic hearts.     

Triiodothyronine receptors in lymphocytes of newborn and adult rats.

Cytoplasmic and nuclear incorporation of 125I triiodothyronine by thymic lymphocytes has been demonstrated by electron microscopic autoradiography. Incorporation was significantly more pronounced in the newborn than in the adult age. The information emerging from the experime,tal observations contributes further evidence to the more precise interpretation of receptor maturation.     

Increased myocardial stiffness with maintenance of length-dependent calcium activation by female sex hormones in diabetic rats

A decrease in peak early diastolic filling velocity in postmenopausal women implies a sex hormone-related diastolic dysfunction. The regulatory effect of female sex hormones on cardiac distensibility therefore was evaluated in ovariectomized rats by determining the sarcomere length-passive tension relationship of ventricular skinned fiber preparations. Diabetes also was induced in the rat to assess the protective significance of female sex hormones on diastolic function. While ovariectomy had no effect on myocardial stiffness, collagen content, or titin ratio, a significant increase in myocardial stiffness was observed in diabetic rat only when female sex hormones were intact. The increased stiffness in diabetic-sham rats was accompanied by an elevated collagen content resulting from increases in the levels of procollagen and Smad2. Surprisingly, the increased myocardial stiffness in diabetic-sham rats was accompanied by a shift toward a more compliant N2BA of cardiac titin isoforms. The pCa-active tension relationship was analyzed at fixed sarcomere lengths of 2.0 and 2.3 μm to determine the magnitude of changes in myofilament Ca(2+) sensitivity between the two sarcomere lengths. Interestingly, high expression of N2BA titin was associated with a suppressed magnitude of changes in myofilament Ca(2+) sensitivity only in the diabetic-ovariectomized condition. Estrogen supplementation in diabetic-ovariectomized rats partially increased myocardial stiffness but completely reversed the change in myofilament Ca(2+) sensitivity. These results indicate a restrictive adaptation of myocardium governed by female sex hormones to maintain myofilament activity in compensation to the pathophysiological induction of cardiac dilatation by the diabetic condition.     

Effect of aloe vera (Aloe barbadensis Miller) gel on doxorubicin-induced myocardial oxidative stress and calcium overload in albino rats

Administration of a single dose of doxorubicin (DOX) (7.5 mg/kg, i.v.) produces cardiotoxicity, manifested biochemically by significant decrease in blood glutathione (GSH) and tissue GSH along with elevated levels of serum lactate dehydrogenase (LDH) and serum creatine phosphokinase (CPK). In addition, cardiotoxicity was further confirmed by significant increase in lipid peroxides expressed as malondialdehyde (MDA, secondary indicator of lipid peroxidation), tissue catalase and tissue superoxide dismutase (SOD). Administration ofA. vera gel (100 and 200 mg/kg) orally for 10 days produced a significant protection against cardiotoxicity induced by DOX evidenced by significant reductions in serum LDH, serum CPK, cardiac lipid peroxides, tissue catalase and tissue SOD along with increased levels of blood and tissue GSH. The results revealed that A. vera gel produced a dose dependent protection against DOX induced cardiotoxiaty.     

Isoproterenol fails to produce myocardial necrosis in streptozotocin-induced diabetic rats.

Biochemical alterations in the hearts of non-diabetic and 5 weeks of streptozotocin-induced diabetic rats following isoproterenol (ISO) administration were compared. Serum lactate dehydrogenase (LDH) and myocardial adenosine triphosphate (ATP), creatine phosphate (CP), lactate and glycogen were used as indices of myocardial injury. Hearts from diabetic rats (blood glucose greater than 350 mg/dl), before ISO administration, had normal lactate levels but significantly low high-energy phosphate (HEP) levels and high glycogen levels in comparison to non-diabetic rats. No difference was observed in serum LDH levels between these two groups. ISO administration to non-diabetic rats caused myocardial necrosis as evidenced by a significant depletion of myocardial glycogen and HEPs along with significant myocardial lactate accumulation and an increase in serum LDH. However, the hearts from diabetic rats failed to show any significant HEP depletion, accumulation of lactate and leakage of LDH into serum following ISO-administration, though myocardial glycogen level was significantly lowered. These observations, in conjunction with earlier reports, point to the hypothesis that, in diabetes, there are certain alterations in the sarcolemma which hamper the process by which ISO causes myocardial necrosis.     

Liver iron overload induced by tamoxifen in diabetic and non-diabetic female Wistar rats

Tamoxifen (TX), a drug used in the treatment of breast cancer, may cause hepatic changes in some patients. The consequences of its use on the liver tissues of rats with or without diabetes mellitus (DM) have not been fully explored. The purpose of this study was to evaluate the correlation between plasma hepatic enzyme levels and the presence of iron overload in the hepatic tissue of female Wistar rats with or without streptozotocin-induced DM and using TX. Female rats were studied in control groups: C-0 (non-drug users), C-V (sorbitol vehicle only) and C-TX (using TX). DM (diabetic non-drug users) and DM-TX (diabetics using TX) were the test groups. Sixty days after induced DM, blood samples were collected for glucose, alanine aminotransferase (ALT), aspartate aminotransferase (AST) alkaline phosphatase (ALP) and bilirubin measures. Hepatic fragments were processed and stained with hematoxylin and eosin, Masson’s trichrome, Perls. The hepatic iron content was quantified by atomic absorption spectrometry. AST, ALT and ALP levels were significantly elevated in the DM and DM-TX groups, with unchanged bilirubin levels. Liver iron overload using Perls stain and atomic absorption spectrometry were observed exclusively in groups C-TX and DM-TX. There was positive correlation between AST, ALT and ALP levels and microscopic hepatic siderosis intensity in group DM-TX. In conclusion, TX administration is associated with liver siderosis in diabetic and non-diabetic rats. In addition, TX induced liver iron overload with unaltered hepatic function in non-diabetic rats and may be a useful tool for investigating the biological control of iron metabolism.     

Dietary nitrite inhibits early glomerular injury in streptozotocin-induced diabetic nephropathy in rats.

Increased production of reactive oxygen species (ROS) is a key event leading to microvascular complications, including nephropathy, in diabetes mellitus (DM). Excessive ROS and oxidative stress in DM have been reported to be associated with subsequent impaired nitric oxide (NO) bioavailability. The aim of this study is to examine the beneficial function of dietary nitrite supplementation as an interventional NO donor to attenuate early progression of diabetic nephropathy. To test this hypothesis, male Sprague-Dawley rats were randomly divided into four groups: non-diabetic rats given water with or without nitrite (nitrite-treated or untreated, respectively), and streptozotocin-induced diabetic rats given water with or without nitrite (nitrite-treated or untreated, respectively). After a 4 week experimental period, untreated diabetic rats exhibited significantly higher malondialdehyde (MDA) levels in the kidney compared with untreated non-diabetic rats, accompanied by a reduction in levels of endogenous NO synthase-derived nitrite. However, dietary nitrite supplementation to diabetic rats not only decreased MDA levels but also increased nitrite levels in the kidney to the same levels as in the non-diabetic kidney. These improvements accompanied an improvement in the parameters of glomerular injury, including urinary protein and albumin excretion, histopathological glomerular hypertrophy, and mesangial matrix accumulation. These results indicate that dietary nitrite is effective in the prevention of early diabetic glomerular injury in which NO bioavailability is impaired.     

Role of the cyclooxygenase pathway in the protection against postischemic stunning in conscious sheep

Objective: There are controversial reports in conscious animals regarding the role of cyclooxygenase-2 in late preconditioning (LP). This study analyzed the effect of COX-2 involvement in non-preconditioned hearts (NP) and in mediation of LP protection against stunning in conscious sheep submitted to a prolonged reversible ischemia. Methods: Six groups were considered: NP: 12 min ischemia and 120 min reperfusion; LP consisting of six periods of 5 min-ischemia-5 min reperfusion 24 h before the 12 min ischemia; NP and LP with either the non-selective COX-1 and COX-2 inhibitor, aspirin (20 mg/kg), or the specific COX-2 inhibitor, celecoxib (3 mg/kg) before the 12 min ischemic period. Results: Mean postischemic wall thickening fraction (as % of preischemic values) improved from 49.6 ± 4.0% in NP to 72.5 ± 3.5% in LP (p < 0.01) and a similar protection was obtained with aspirin and celecoxib in NP hearts (p < 0.01). Neither aspirin nor celecoxib administration prior to the prolonged ischemia on day 2 abrogated LP improvement of postischemic dysfunction. Moreover, LP with aspirin improved the protective response (80.7 ± 2.6%) over that obtained with aspirin in NP hearts (66.6 ± 4.7%, p < 0.05). This effect was not obtained with celecoxib. Conclusions: Aspirin and celecoxib showed that COX-2 has a detrimental effect on mechanical cardioprotection in NP hearts of conscious sheep submitted to a prolonged reversible ischemia, and does not seem to participate as mediator of LP. Aspirin revealed a similar COX-1 deleterious action, since only when both COX-1 and COX-2 were inhibited, LP was put in evidence adding functional improvement over that obtained in NP hearts treated with aspirin.     

Altered myocardial prostaglandin synthesis in spontaneously diabetic rats

Patients with diabetes mellitus have an increased susceptibility to heart disease. The exact mechanism for this phenomenon is unclear. Abnormalities in prostaglandin (PG) production have been suggested as a possible cause. In this connection, we examined the PG synthetic capacity of cardiac microsomes from spontaneously diabetic rats. Cardiac microsomes from diabetic and control rats produced varying amounts of 6-keto-PGF1 alpha (stable degradation product of PGI2), PGE2, PGD2, PGF2 alpha, and TXB2 (stable breakdown product of TXA2). In both instances the production of 6-keto-PGF1 alpha predominated, however, microsomes from diabetic rats showed markedly greater conversion of arachidonic acid to all the PG products, especially 6-keto-PGF1 alpha. When PGF2 alpha metabolism was detected between diabetic and control heart preparations. These results show an enhanced cyclooxygenase activity in diabetic rat hearts without any change in prostaglandin dehydrogenase activity. Such a change may promote some of the cardiac alterations seen in diabetic mellitus.     

Increases in myocardial cyclic GMP attenuate contractile delay in myocardial stunning

We tested the hypothesis that the effects of myocardial stunning would be reduced by cyclic GMP in rabbit hearts. In three groups of anesthetized open-chest New Zealand white rabbits, myocardial stunning was produced by 15 min of occlusion of the left anterior descending coronary artery followed by 15 min of reperfusion repeated twice. Either control vehicle (saline plus 1% dimethyl sulfoxide) or 8-bromo-cyclic GMP (8-Br-cGMP (10(-4) and 10(-3) M)) was topically applied to the left ventricular surface. Hemodynamic (left ventricular and aortic pressures) and functional parameters (wall thickening, delay in onset of wall thickening, and rate of wall thickening) were determined. Coronary blood flow (microspheres) and O2 extraction (microspectrophotometry) were used to determine myocardial O2 consumption (VO2). Myocardial stunning was observed in the control group through an increased delay in onset of myocardial wall thickening (29 +/- 7 versus 55 +/- 16 ms) and decreased maximal rate of wall thickening (20 +/- 8 versus 11 +/- 3 mm x s(-1)). After treatment with 8-Br-cGMP 10(-4) and 10(-3) M, stunning did not increase the delay (37 +/- 5 versus 39 +/- 7 and 39 +/- 7 versus 28 +/- 8 ms). Myocardial stunning did not significantly alter VO2. 8-Br-cGMP 10(-3) M significantly decreased subepicardial VO2 (6.2 +/- 0.8 versus 3.7 +/- 0.6 mL O2 x min(-1) 100 g(-1)) and insignificantly decreased subendocardial VO2 (8.6 +/- 0.9 versus 6.3 +/- 1.2 mL O2 x min(-1) x 100 g(-1)) when compared with the vehicle-treated rabbits. We conclude that increasing cyclic GMP reduced the effects of myocardial stunning in the rabbit heart by ameliorating the delay in onset of wall thickening and decreasing the local O2 costs in the stunned region.     

糖尿病大鼠心肌功能的改变及其机制*

目的:观察钙敏感受体(CaSR)表达变化在2型糖尿病大鼠心功能降低中的作用。方法:Wistar大鼠随机分成3组:对照组、糖尿病4周和8周组。糖尿病组大鼠给予高糖高脂饮食喂养,4周后腹腔注射链脲佐菌素建立2型糖尿病模型。通过HE染色观察心脏形态学变化,通过超声心动仪检测心脏功能的变化,通过Western blot检测心肌组织CaSR和PKC-α蛋白表达的变化。结果:与对照组相比,糖尿病大鼠心脏收缩和舒张功能降低,心肌组织出现不规则收缩带,且随着病程延长逐渐加重,同时心肌组织CaSR和PKC-α蛋白表达减少。结论:糖尿病大鼠心肌CaSR等蛋白的表达降低,从而引起细胞内钙紊乱,导致心功能下降。     

β-catenin和WISP-1在糖尿病大鼠心肌中的表达

目的观察Wnt信号通路中β-catenin及其下游靶基因WISP～1在糖尿病大鼠心肌组织中的表达,分析Wnt/β-catenin信号通路在糖尿病大鼠心肌损伤中的作用。方法雄性SD大鼠随机分为正常对照组（Control Group）和糖尿病模型组（DMGroup）,腹腔注射STZ55mg／kg诱导糖尿病大鼠模型,喂养至8周。测定大鼠的空腹血糖、心体比和心肌羟脯氨酸含量;电镜观察心肌超微结构变化,免疫组化法观察心肌组织β-catenin和WISP-1的表达。结果与对照组相比,糖尿病组大鼠空腹血糖水平明显增加,心体比增加,心肌羟脯氨酸含量增高。心肌超微结构显示肌纤维断裂,线粒体呈空泡样改变。心肌β-catenin和WISP-1蛋白表达增加。结论糖尿病大鼠心肌组织β-catenin和其下游靶基因WISP-1表达增加,提示Wnt／β-catenin信号通路的激活参与糖尿病所致的心肌损伤。     

Antioxidant treatment of diabetic rats inhibits lipoprotein oxidation and cytotoxicity

Increased lipid peroxidation products were detected in a lipoprotein fraction containing very low density lipoprotein (VLDL) and low density lipoprotein (LDL) obtained from rats made diabetic by streptozotocin injection. The enhanced oxidation in the diabetic VLDL plus LDL fraction correlated with the in vitro toxicity of this lipoprotein fraction to proliferating fibroblasts. In contrast, high density lipoprotein (HDL) was not cytotoxic. That the increased oxidation and development of cytotoxic activity in the diabetic VLDL + LDL was related to the diabetes was shown by the fact that insulin treatment of diabetic animals inhibited both oxidation and cytotoxicity of VLDL + LDL. In contrast, treatment of diabetic rats with the antioxidants vitamin E or probucol after diabetes was established also inhibited both the in vivo oxidation and in vitro cytotoxicity of diabetic VLDL + LDL, but without altering hyperglycemia. Vitamin E or probucol treatment thus allowed separation of the oxidation process from the hyperglycemia occurring in experimental diabetes. The mechanisms by which diabetes in humans or experimental animals leads to the various manifestations of tissue damage are unknown; however, these studies demonstrate for the first time that a relationship exists between the in vivo oxidation of lipoproteins in diabetes and the potential for tissue damage as monitored by in vitro cytotoxicity. Furthermore, these results suggest that the mechanism for certain aspects of tissue damage accompanying experimental diabetes may be mediated by lipid peroxidation products.     

Hydrogen sulfide inhibits myocardial injury induced by homocysteine in rats

Hyperhomocysteinemia (HHcy) is a critical independent risk factor for cardiovascular diseases. However, to date, no satisfactory strategies to prevent HHcy exist. Since homocysteine (Hcy) and endogenous H₂S are both metabolites of sulfur-containing amino acids, we aimed to investigate whether a metabolic product of Hcy and H₂S, may antagonize in part the cardiovascular effects of Hcy. In the HHcy rat model injected subcutaneously with Hcy for 3 weeks, H₂S levels and the H₂S-generating enzyme cystathionine γ lyase (CSE) activity in the myocardium were decreased. The intraperitoneal injection of H₂S gas saturation solution significantly reduced plasma total Hcy (tHcy) concentration and decreased lipid peroxidation formation (i.e., lowered manodialdehyde and conjugated diene levels in myocardia and plasma). The activities of myocardial mitochondrial respiratory enzymes succinate dehydrogenase, cytochrome oxidase, and manganese superoxide dismutase, related to reactive oxygen species metabolism, were significantly dysfunctional in HHcy rats. The H₂S administration restored the level of enzyme activities and accelerated the scavenging of H₂O₂ and superoxide anion generated by Hcy in isolated mitochondria. The H₂S treatment also inhibited the expression of glucose-regulated protein 78, a marker of endoplasmic reticulum (ER) stress, induced by Hcy in vivo and in vitro. Thus, HHcy impaired the myocardial CSE/H₂S pathway, and the administration of H₂S protected the myocardium from oxidative and ER stress induced by HHcy, which suggests that an endogenous metabolic balance of sulfur-containing amino acids may be a novel strategy for treatment of HHcy.     

Losartan inhibits myosin isoform shift after myocardial infarction in rats

Hypertrophy and heart failure following a myocardial infarction in rodents are accompanied by a switch of myosin isoforms from V₁ to V₃. The angiotensin II receptor blocker, Losartan, has been demonstrated to improve cardiac function and long-term survival after myocardial infarction. In this study we have investigated whether chronic Losartan treatment affects myosin isoform composition in the hearts of rats following a myocardial infarction. Rats were subjected to coronary artery ligation and received either Losartan (1 g/L) in the drinking water or water only. Four months after myocardial infarction, rats were classified as having either congestive heart failure (cMI) or uncomplicated myocardial infarction (uMI) based on their lung weight to body weight ratio (LW/BW). Compared with sham operated rats, uMI rats showed a 68.5% increase in the relative contribution of V₃ and a 33.7% decrease in the relative contribution of V₁ (p < 0.05). Untreated cMI showed 39.7% more V₃ and 38.2% less V₁ when compared with untreated uMI (p < 0.05). Losartan treatment after myocardial infarction reduced the incidence of cMI from 30.4 to 4.5% and scar size from 1.52 ± 0.07 to 0.94 ± 0.11 cm² respectively. The percentage of V₁ in Losartan treated uMI (LuMI) was 25.2% higher than the percentage of V₁ in untreated uMI (p < 0.05), whereas the percentage of V₃ in LuMI was 24.2% lower than that in untreated uMI (p < 0.05). A positive correlation of V₃ myosin and scar area was observed. Our study suggests that expression of V₃ myosin in the left ventricle is associated with scar size and the progress of hemodynamic changes after myocardial infarction. Losartan treatment reduces scar size and wall stress of the heart after the infarct, and therefore inhibits the signals shifting myosin isoform expression from V₁ to V₃ after a myocardial infarction.     

Impaired in vivo myocardial reactivity to norepinephrine in diabetic rats

The effects of long-term diabetes with and without insulin treatment on in vivo myocardial contractile activity were studied under basal conditions and as a function of intravenously infused norepinephrine. Diabetes was induced by iv injection of streptozotocin (50 mg/kg). Insulin-treated diabetic rats received 5 units per day of isophane insulin suspension. The duration of the study was 8 weeks. In vivo myocardial contractility measurements were performed in ketamine-xylazine-anesthetized rats using a miniature catheter-tip pressure transducer advanced through the right carotid artery into the left ventricle. Peak positive dP/dt and intraventricular developed pressure were comparable among the groups when measured under basal conditions; however, the magnitude of the response to variable doses of norepinephrine (6 X 10(-12) to 6 X 10(-8) mole/kg body wt) were significantly diminished in diabetic rats, but the sensitivity was unchanged. Negative dP/dt was decreased under basal conditions and in response to norepinephrine in diabetic rats. Insulin treatment to diabetic rats prevented these changes, but heart rate was elevated. These results demonstrate that the in vivo cardiovascular reactivity of diabetic rats to norepinephrine is significantly attenuated.     

Allicin protects against myocardial apoptosis and fibrosis in streptozotocin-induced diabetic rats

To evaluate the cardioprotective effect of allicin (AL) on myocardial injury of streptozotocin (STZ)-induced diabetic rats and to further explore its underlying mechanisms. Hyperglycemia was induced in rats by single intraperitoneal injection of STZ (40 mg/kg). Three days after STZ induction, the hyperglycemic rats (plasma glucose levels ≥ 16.7 mmol/l) were treated with AL by intraperitoneal injection at the doses of 4 mg/kg, 8 mg/kg, and 16 mg/kg daily for 28 days. The fasting blood glucose levels were measured on every 7th day during the 28 days of treatment. The body weight, blood glucose, and parameter of cardiac function were detected after 4 weeks to study the cardioprotective effects of AL on diabetic rats in vivo. The apoptotic index of cardiomyocytes was estimated by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. The expressions of Fas, Bcl-2, CTGF, and TGF-β(1) protein were studied by immunohistochemistry. Laser scanning confocal microscopy technique was utilized to observe the effects of AL on intracellular calcium concentration ([Ca(2+)](i)) in rat ventricular cardiomyocytes. AL at the doses of 4 mg/kg, 8 mg/kg, and 16 mg/kg significantly reduced blood glucose levels in a dose-dependent manner and increased body weight as well compared with the model group. Hemodynamic parameters including left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), and maximum rate of left ventricular pressure rise and fall (+dp/dtmax and -dp/dtmax) were significantly restored back to normal levels in AL-treated (8 mg/kg and 16 mg/kg) rats compared with diabetic model rats. AL markedly inhibited cardiomyocyte apoptosis induced by diabetic cardiac injury. Further investigation revealed that this inhibitory effect on cell apoptosis was mediated by increasing anti-apoptotic protein Bcl-2 and decreasing pro-apoptotic protein Fas. Additional experiments demonstrated AL abrogated myocardial fibrosis by blocking the expressions of CTGF and TGF-β(1) protein. AL shows protective action on myocardial injury in diabetic rats. The possible mechanisms were involved in reducing blood glucose, correcting hemodynamic impairment, reducing Fas expression, activating Bcl-2 expression, decreasing intracellular calcium overload, inhibiting the expressions of TGF-β(1) and CTGF, and further improving cardiac function.