The Cardioprotective Effects of Remote Ischemic Conditioning in a Rat Model of Acute Myocardial Infarction.

BACKGROUND Cardiac remote ischemic conditioning (RIC) is a noninvasive cardioprotective method in ischemia-reperfusion injury and acute myocardial infarction (AMI). The aims of this study were to investigate the effects of RIC in a rat model of AMI. MATERIAL AND METHODS Adult male Sprague-Dawley rats included the AMI group that underwent ligation of the left anterior descending (LAD) coronary artery (n=24), the RIC group that consisted the AMI rat model treated with RIC once daily in the left hind limb until days 1, 7 and 14 (n=24), and the sham group (n=24). Myocardial infarct size was measured by routine histology with triphenyltetrazolium chloride (TTC) and Masson's trichrome histochemical staining for myocardial necrosis and fibrosis, respectively. Serum levels of Bcl-2, Bax, caspase-3, and inducible nitric oxide synthase (iNOS) were measured by enzyme-linked immunosorbent assay (ELISA). The apoptosis index was detected using the TUNEL assay. Spectrophotometry of the myocardium was used to identify mitochondrial complexes and myocardial ATP. RESULTS The RIC group showed improved cardiac hemodynamics, reduced the size of the myocardial infarction, upregulated expression of Bcl-2, and down-regulation of the levels of Bax, caspase-3, and iNOS, and reduced cardiac myocyte apoptosis and inhibited the opening of the mitochondrial permeability transition pore (MPTP). CONCLUSIONS In a rat model of AMI, RIC improved the hemodynamic index, reduce the levels of apoptosis and myocardial injury, and improved mitochondrial function.

[Anti-arrhythmic effects of taurine-magnesium coordination compound on torsades de pointes].

OBJECTIVES: To investigate the effect of taurine magnesium coordination compound (TMCC) on torsades de pointes (TdP) in isolated guinea pig hearts. METHODS: Healthy male guinea pigs weighting 250~300 g were randomly divided into 4 groups:①TdP model group (n=7):Isolated hearts were perfused by normal K-H solution 20 minutes, then perfused by slowly activated delayed rectifier potassium current(IKs) blocker 10µmol/L Chromanol 293B under hypokalemic solution(1.8 mmol/L) to establish TdP model;②~④ TdP model + TMCC group (n=6):Isolated hearts were perfused by normal K-H solution for 20 minutes, then perfused by IKs blocker 10µmol/L Chromanol 293B under hypokalemic solution(1.8 mmol/L) for 60 minutes, at the same time TMCC which concentration was 1, 2, 4 mmol/L was administered respectively by Langendorff retrograde aortic perfusion method. Cardiac surface electrocardiogram of guinea pigs in vitro was collected and recorded by Biopac electrophysiological recorder. Incidence of TdP, transmural dispersion of repolarization (TDR), instability of QT interval were acquired from Lead Ⅱ electrocardiograph (ECG) wave forms to describe the effect of TMCC on TdP model. Datas were acquired at the time of 20 min and pre-TdP, in case there was no TdP observed, a value of 60 min was entered for calculation purpose. RESULTS: Incidence of TdP in TdP model group was 6/7. TdP incidence could be decreased significantly by 1, 2, 4 mmol/L TMCC, and was 5/6, 1/6, 0/6 respectively. Compared with the pre-drug, Chromanol 293B under hypokalemic solution in TdP model group increased TDR(corrected) evidently(P<0.01). Compared with the pre-drug, 1, 2, 4 mmol/L TMCC in TdP model + TMCC group could decrease the increased TDR(corrected) induced by Chromanol 293B under hypokalemic solution(P>0.05). Compared with the TdP model group, 2, 4 mmol/L TMCC could evidently decrease the instability of QT interval induced by Chromanol 293B under hypokalemic solution(P<0.05). During the establishment of TdP model, P waves in more than one cardiac cycle continuously were disappeared in ECG. However, P wave could always be seen independent in ECG acquired from TdP model + TMCC group. CONCLUSIONS: TMCC can play the role against TdP through decreasing TDR and instability of QT interval, and inhibiting early after depolarization(EAD).

Therapeutic effects of a taurine-magnesium coordination compound on experimental models of type 2 short QT syndrome.

Short QT syndrome (SQTS) is a genetic arrhythmogenic disease that can cause malignant arrhythmia and sudden cardiac death. The current therapies for SQTS have application restrictions. We previously found that Mg· (NH2CH2CH2SO3)2· H2O, a taurine-magnesium coordination compound (TMCC) exerted anti-arrhythmic effects with low toxicity. In this study we established 3 different models to assess the potential anti-arrhythmic effects of TMCC on type 2 short QT syndrome (SQT2). In Langendorff guinea pig-perfused hearts, perfusion of pinacidil (20 µmol/L) significantly shortened the QT interval and QTpeak and increased rTp-Te (P<0.05 vs control). Subsequently, perfusion of TMCC (1-4 mmol/L) dose-dependently increased the QT interval and QTpeak (P<0.01 vs pinacidil). TMCC perfusion also reversed the rTp-Te value to the normal range. In guinea pig ventricular myocytes, perfusion of trapidil (1 mmol/L) significantly shortened the action potential duration at 50% (APD50) and 90% repolarization (APD90), which was significantly reversed by TMCC (0.01-1 mmol/L, P<0.05 vs trapidil). In HEK293 cells that stably expressed the outward delayed rectifier potassium channels (IKs), perfusion of TMCC (0.01-1 mmol/L) dose-dependently inhibited the IKs current with an IC50 value of 201.1 µmol/L. The present study provides evidence that TMCC can extend the repolarization period and inhibit the repolarizing current, IKs, thereby representing a therapeutic candidate for ventricular arrhythmia in SQT2.

Acute and chronic effects of taurine magnesium coordination compound on cardiac sodium channel Nav1.5.

It has been previously demonstrated that taurine magnesium coordination compound (TMCC) produces antiarrhythmic effects in vivo. The present study investigated the acute and chronic effect of TMCC on sodium channels in HEK cells stably expressing human cardiac Nav1.5 sodium channels. The current amplitude, activation and inactivation kinetics, recovery time from inactivation, and use­dependent block of sodium channels were analyzed using the whole­cell patch clamp technique. Western blotting was used to analyze Nav1.5 expression following chronic TMCC treatment. In HEK cells expressing Nav1.5 channels, TMCC acutely inhibited Na+ currents in a dose­dependent manner. In addition, acute application of TMCC shifted the activation and inactivation curves, and prolonged the recovery time from inactivation, but did not exhibit a use­dependent block of Nav1.5. By contrast, chronic TMCC treatment only produced a use­dependent block of Nav1.5 and downregulated Nav1.5 expression. The results of the present study suggested that TMCC may produce antiarrhythmic actions via acute inhibition of sodium channel currents and chronic downregulation of Nav1.5 expression.

Effects of non-invasive remote ischemic conditioning on rehabilitation after myocardial infarction.

Recent studies have demonstrated that remote ischemic conditioning (RIC) creates cardioprotection against ischemia/reperfusion injury and myocardial infarction (MI); however, the effects of non-invasive remote ischemic conditioning (nRIC) on prognosis and rehabilitation after MI (post-MI) remain unknown. We successfully established MI models involving healthy adult male Sprague-Dawley rats. The nRIC group repeatedly underwent 5 min of ischemia and 5 min of reperfusion in the left hind limb for three cycles every other day until weeks 4, 6, and 8 after MI. nRIC improved cardiac hemodynamic function and mitochondrial respiratory function through increasing myocardial levels of mitochondrial respiratory chain complexes I, II, III, IV, and adenosine triphosphate (ATP) and decreasing the activity of nitric oxide synthase (NOS). nRIC could inhibit cardiomyocytes apoptosis and reduce myocardium injury through raising the expression of Bcl-2 and reduced the content of creatine kinase-MB, cardiac troponin I and Bax. The results indicated that long-term nRIC could accelerate recovery and improve prognosis and rehabilitation in post-MI rats.

[The effects of dioscin on myocardial contraction and sodium-cal-cium exchanger].

OBJECTIVE: To investigate the inotropic effects of dioscin (Dio)in rat isolated-heart and intracellular free calcium concentration in isolated rat ventricular myocytes and to explore its mechanism preliminarily. METHODS: Left ventricle contractile function was measured using the Langendorff non-recirculating mode of isolated rat heart perfusion. Effects of dioscin and dioscin+SEA0400, sodium-calcium exchanger (NCX) inhibitor, were investigated by measuring left ventricular systolic pressure (LVSP) and left ventricular end diastolic pressure (LVEDP). Also, heart rate (HR), peak rate of rise/fall of left ventricular pressure (±dp/dtmax) of isolated rat heart were calculated; Effects of dioscin and SEA0400 on intracellular free calcium concentration in rat H9c2 cells were measured by Fluo3-AM and then detected the fluorescence intensity with confocal microscopy. RESULTS: With 1 µmol/L dioscin, LVSP was significantly increased by 19.7% (P<0.01) and dp/dtmax was increased by 9.6%; With 1 µmol/L dioscin, the relative fluorescence intensity of intracellular free calcium concentrations were strong significantly(P<0.01). While in presence of SEA0400, the relative fluorescence intensity was changed to 17.09±0.63 (P<0.01) by 1 µmol/L dioscin. With 1 µmol/L dioscin, the relative fluorescence intensity was weak(P<0.01) without calcium or sodium in the extracellular fluid. CONCLUSIONS: Dioscin shows positive inotropic effect on isolated rat heart, enhancing the LVSP and +dp/dtmax; Dioscin increases the intracellular concentration of Ca2+ in the cardiac myocytes by increasing Na+ influx and facilitating the reverse mode of the sodium-calcium exchanger.

Biological evaluation of a cytotoxic 2-substituted benzimidazole copper(II) complex: DNA damage, antiproliferation and apoptotic induction activity in human cervical cancer cells.

Exploring novel chemotherapeutic agents is a great challenge in cancer medicine. To that end, 2-substituted benzimidazole copper(II) complex, [Cu(BMA)Cl2]·(CH3OH) (1) [BMA = N,N'-bis(benzimidazol-2-yl-methyl)amine], was synthesized and its cytotoxicity was characterized. The interaction between complex 1 and calf thymus DNA was detected by spectroscopy methods. The binding constant (K b = 1.24 × 10(4 )M(-1)) and the apparent binding constant (K app = 6.67 × 10(6 )M(-1)) of 1 indicated its moderate DNA affinity. Complex 1 induced single strand breaks of pUC19 plasmid DNA in the presence of H2O2 through an oxidative pathway. Cytotoxicity studies proved that complex 1 could inhibit the proliferation of human cervical carcinoma cell line HeLa in both time- and dose-dependent manners. The results of nuclei staining by Hoechst 33342 and alkaline single-cell gel electrophoresis proved that complex 1 caused cellular DNA damage in HeLa cells. Furthermore, treatment of HeLa cells with 1 resulted in S-phase arrest, loss of mitochondrial potential, and up-regulation of caspase-3 and -9 in HeLa cells, suggesting that complex 1 was capable of inducing apoptosis in cancer cells through the intrinsic mitochondrial pathway.

[Study on the constituents of essential oil of Shunaoxin dropping pills by GC-MS].

OBJECTIVE: To study the constituents of essential oil from Shunaoxin dropping pills by GC-MS. METHODS: The essential oil from Shunaoxin dropping pills were extracted by absolute alcohol and analyzed by GC-MS. RESULTS: 15 components from the essential oil of Shunaoxin dropping pills were identified. CONCLUSION: The main components in the essential oil of Shunaoxin dropping pills are lactones such as Z-ligustilide, senkyunolide A,3-butylphthalide and 3-butylidenephthalide, other components are organic acids such as ethyl linoleate, 9,12-octadecadienoic acid and ethyl palmitate.

Effects of Fufang Biejia Ruangan pills on hepatic fibrosis in vivo and in vitro.

AIM: To explore the protective effect and the relevant mechanisms of Fufang Biejia Ruangan Pills (FFBJRGP) on hepatic fibrosis in vivo and in vitro. METHODS: Hepatic fibrosis was induced by carbon tetrachloride composite factors. Adult Wistar rats were randomly divided into four groups: normal control group; hepatic fibrosis model group; FFBJRGP-treated group at a daily dose of 0.55 g/kg; and colchicine-treated group at a daily dose of 0.1 g/kg. The effects of FFBJRGP on liver function, serum levels of hyaluronic acid (HA), type IV collagen (CIV), type III procollagen (PC III), laminin (LN), histopathology, and expression of transforming growth factor (TGF-ß1) and Smad3 in hepatic fibrosis were evaluated in vivo. The effects of FFBJRGP on survival rate, hydroxyproline content and cell cycle distribution were further detected in vitro. RESULTS: Compared with the hepatic fibrosis model group, rats treated with FFBJRGP showed a reduction in hepatic collagen deposition and improvement in hepatic lesions. Compared with those of the model group, the activities of alanine aminotransferase (62.0 ± 23.7 U/L) and aspartate aminotransferase (98.8 ± 40.0 U/L) in the FFBJRGP-treated group were decreased (50.02 ± 3.7 U/L and 57.2 ± 30.0 U/L, respectively, P < 0.01). Compared with those in the model group, the levels of PCIII (35.73 ± 17.90 µg/mL), HA (563.82 ± 335.54 ng/mL), LN (89.57 ± 7.59 ng/mL) and CIV (29.20 ± 6.17 ng/mL) were decreased to 30.18 ± 9.41, 456.18 ± 410.83, 85.46 ± 7.51 and 28.02 ± 9.45 ng/mL, respectively. Reverse-transcriptase polymerase chain reaction and Western blotting also revealed that expression of TGF-ß1 and Smad3 were down-regulated in vivo. Cell proliferation was inhibited, the level of hydroxyproline was decreased compared with the control group (P < 0.01), and the cell cycle was redistributed when exposed to FFBJRGP in vitro. CONCLUSION: FFBJRGP inhibits hepatic fibrosis in vivo and in vitro, which is probably associated with downregulation of fibrogenic signal transduction of the TGF-ß-Smad pathway.

Activities of a novel Schiff base copper(II) complex on growth inhibition and apoptosis induction toward MCF-7 human breast cancer cells via mitochondrial pathway.

In this study, we investigated the newly synthesized Schiff base copper(II) complex, [Cu(II)(5-Cl-pap)(OAc)(H(2)O)]·2H(2)O (1) (5-Cl-pap=N-2-pyridiylmethylidene-2-hydroxy-5-chloro-phenylamine), inducing growth inhibition and apoptosis in human breast cancer cell line MCF-7 and its potential antitumor mechanism. The results of cytotoxicity research, fluorescence microscopic observation and flow cytometric analysis revealed that complex 1 could significantly suppress MCF-7 cell viability and induce apoptosis. Comet assay indicated that severe DNA fragmentation in MCF-7 cells was induced after treatment with complex 1. Flow cytometric analysis showed that the antitumor effect of complex 1 on MCF-7 cells was associated with the cell cycle arrest. In addition, atomic absorption analyses displayed that complex 1 caused a rapid increase of intracellular copper uptake in MCF-7 cells in a time-dependent manner. The present work suggested that the antitumor mechanism of complex 1 on MCF-7 cells might be via the mitochondrial pathway, based on the up-regulated expression of Bax and activation of caspase-9 and caspase-3.

Noninvasive delayed limb ischemic preconditioning in rats increases antioxidant activities in cerebral tissue during severe ischemia-reperfusion injury.

BACKGROUND: To study the protection offered by noninvasive delayed limb ischemic preconditioning (NDLIP) against cerebral ischemia reperfusion (I/R) injury in rats. MATERIALS AND METHODS: Healthy male Wistar rats were randomly divided into four groups. The delayed protection offered by NDLIP was estimated in light of changes in the neural behavior marker and cerebral tissue antioxidative ability. Neurological functions were studied by observing neural behavior. Total superoxide dismutase (T-SOD), manganese-superoxide dismutase (Mn-SOD), glutathione peroxidase (GSH-PX), and xanthine oxidase (XOD) activity in cerebral tissue and malonaldehyde (MDA) content were detected using a spectrophotometer. Mn-SOD mRNA was measured by the reverse transcription polymerase chain reaction method. RESULTS: Cerebral infarct size was diminished in the early cerebral ischemia preconditioning (ECIP)+I/R and NDLIP+I/R groups compared with the I/R group (P < 0.05). The cortical and hippocampal antioxidant enzyme activity and Mn-SOD expression were increased in the ECIP+I/R and NDLIP+I/R groups. In contrast, the cortical and hippocampal XOD activity and MDA content decreased in the ECIP+I/R and NDLIP+I/R groups. CONCLUSIONS: NDLIP decreased cerebral infarct size, increased cerebral antioxidative ability after I/R injury, and decreased peroxidative damage. The antioxidative protection offered by NDLIP was as effective as that offered by ECIP.

Acetylated anthraquinone glycosides from Cassia obtusifolia.

Three new acetylated anthraquinone glycosides (1-3) were isolated from the seed of Cassia obtusifolia, together with one parent anthraquinone glycoside (1a). Their structures were determined on the basis of spectroscopic methods and physicochemical properties as obtusifoline-2-O-ß-d-2, 6-di-O-acetylglucopyranoside (1), obtusifoline-2-O-ß-d-glucopyranoside (1a), obtusifoline-2-O-ß-d-3, 6-di-O-acetylglucopyranoside (2), and obtusifoline-2-O-ß-d-4, 6-di-O-acetylglucopyranoside (3).

Study on potential antitumor mechanism of a novel Schiff base copper(II) complex: synthesis, crystal structure, DNA binding, cytotoxicity and apoptosis induction activity.

A new cytotoxic copper(II) complex with Schiff base ligand [Cu(II)(5-Cl-pap)(OAc)(H(2)O)]·2H(2)O (1) (5-Cl-pap=N-2-pyridiylmethylidene-2-hydroxy-5-chloro-phenylamine), was synthesized and structurally characterized by X-ray diffraction. Single-crystal analysis revealed that the copper atom shows a 4+1 pyramidal coordination, a water oxygen appears in the apical position, and three of the basal positions are occupied by the NNO tridentate ligand and the fourth by an acetate oxygen. The interaction of Schiff base copper(II) complex 1 with DNA was investigated by UV-visible spectra, fluorescence spectra and agarose gel electrophoresis. The apparent binding constant (K(app)) value of 6.40×10(5) M(-1) for 1 with DNA suggests moderate intercalative binding mode. This copper(II) complex displayed efficient oxidative cleavage of supercoiled DNA, which might indicate that the underlying mechanism involve hydroxyl radical, singlet oxygen-like species, and hydrogen peroxide as reactive oxygen species. In addition, our present work showed the antitumor effect of 1 on cell cycle and apoptosis. Flow cytometric analysis revealed that HeLa cells were arrested in the S phase after treatment with 1. Fluorescence microscopic observation indicated that complex 1 can induce apoptosis of HeLa cells, whose process was mediated by intrinsic mitochondrial apoptotic pathway owing to the activation of caspase-9 and caspase-3.

Non-invasive limb ischemic pre-conditioning reduces oxidative stress and attenuates myocardium ischemia-reperfusion injury in diabetic rats.

This study was to explore whether repeated non-invasive limb ischemic pre-conditioning (NLIP) can confer an equivalent cardioprotection against myocardial ischemia-reperfusion (I/R) injury in acute diabetic rats to the extent of conventional myocardial ischemic pre-conditioning (MIP) and whether or not the delayed protection of NLIP is mediated by reducing myocardial oxidative stress after ischemia-reperfusion. Streptozotocin-induced diabetic rats were randomized to four groups: Sham group, the I/R group, the MIP group and the NLIP group. Compared with the I/R group, both the NLIP and MIP groups showed an amelioration of ventricular arrhythmia, reduced myocardial infarct size, increased activities of total superoxide dismutase (SOD), manganese-SOD and glutathione peroxidase, increased expression of manganese-SOD mRNA and decreased xanthine oxidase activity and malondialdehyde concentration (All p < 0.05 vs I/R group). It is concluded that non-invasive limb ischemic pre-conditioning reduces oxidative stress and attenuates myocardium ischemia-reperfusion injury in diabetic rats.

Effects of Haobie Yangyin Ruanjian decoction on hepatic fibrosis induced by carbon tetrachloride in rats.

AIM: To explore the anti-fibrotic effect of Haobie Yangyin Ruanjian decoction (HYRD) on CCl(4)-induced hepatic fibrosis in rats and its modulation on the transforming growth factor (TGF) beta-Smad signaling pathway. METHODS: Fifty-six healthy Wistar rats were randomly divided into five groups: normal control group (n = 6), CCl(4)-induced hepatic fibrosis group (n = 14) and three treatment groups (the treated rats received HYRD via oral administration at daily dosages of 8.2, 2.5 and 0.82 g/kg, respectively) of HYRD (n = 12, respectively). Experimental hepatic fibrosis was induced by subcutaneous injection of carbon tetrachloride solution (CCl(4) dissolved in peanut oil, 4:6, V/V) with 0.5 mL/100 g body weight for the first time, and then 0.3 mL/100 g body weight twice a week for 8 wk. In the former 2 wk, rats were raised by feedstuff I (80% corn meal, 20% lard, 0.5% cholesterol). After 2 wk, they were raised by feedstuff II (corn meal and 0.5% cholesterol). Except for the control group, 30% alcohol solution was given orally to each rat every other day from the beginning, 1 mL for each rat. Liver function parameters and hepatic hydroxyproline content were detected by chromatometry. Serum levels of hyaluronic acid (HA), type IV collagen (CIV), type III precollagen (PCIII) and laminin (LN) were assayed with radioimmunoassay. Deposition of collagen was observed with hematoxylin-eosin staining and collagen staining. Gene expression of TGFbeta1 and Smad3 were detected with real-time reverse transcriptase-polymerase chain reaction and Western blotting, respectively. RESULTS: The serum levels of alanine transaminase and aspartate transaminase were increased in the model group compared with the control group (P < 0.01), and they were decreased in the three treatment groups compared with the model group. The serum levels of total protein and albumin were decreased in the model group and increased in the three treatment groups. The hepatic hydroxyproline content and serum levels of PCIII, HA, LN and CIV were markedly increased in the model group compared with the control group, and decreased in the treatment groups. The gene expression of TGFbeta1 and Smad3 was enhanced in the model group compared with the control group, and HYRD could down regulate their expression. CONCLUSION: HYRD can inhibit hepatic fibrosis induced by CCl(4) in rats, which is probably associated with its down-regulation on fibrogenic signal transduction of TGFbeta-Smad pathway.

[Limited sampling strategy to estimate pharmacokinetic parameters of orally administered metformin hydrochloride].

The present study was to estimate pharmacokinetic parameters of metformin hydrochloride in 20 Chinese healthy volunteers with a limited sampling strategy (LSS), which will provide scientific data for bioequivalence and clinical application. A single dose of metformin was administrated to 20 healthy volunteers. The concentration of metformin in whole blood was determined by validated high performance liquid chromatography (HPLC) method. Multi-linear regression analysis was performed to establish a model to estimate AUC(0-24 h) and Cmax of metformin by LSS method. The LSS models were validated by the Jackknife method. The result indicated: the linearity relationship between AUC(0-24 h) or Cmax and single concentration point was poor. Several models for metformin AUC(0-24 h) or Cmax, estimation were better (r2 > 0.9, P < 0.05). Validation tests indicated that most informative sampling points (C2, C6 for AUC(0-24 h), C1.5, C2 for Cmax) provided accurate estimations of these parameters. So, a multi-linear regression model for estimation pharmacokinetic parameters of metformin by using LSS method is feasible.

Noninvasive limb ischemic preconditioning protects against myocardial I/R injury in rats.

BACKGROUND: Transient limb ischemia induces remote early preconditioning that protects the myocardium from ischemia/reperfusion (I/R). However, it is unknown whether limb ischemia induces remote late preconditioning and whether it induces the same magnitude of cardioprotection compared with cardial ischemic preconditioning (CIP). We tested the hypothesis that late remote preconditioning of noninvasive limb ischemia (NLIP) offers the same magnitude of cardioprotection against myocardium I/R injury. METHODS: Thirty Wistar rats weighing 240-260 g each were randomly divided into three groups: I/R, CIP, and NLIP. The mean arterial pressure (MAP), heart rate (HR), ST-segment, ventricular arrhythmia, and CK-MB, cTnI, and superoxide dismutase (SOD) activity were measured after 0 and 30 min of ischemia and after 120 min of reperfusion. Myocardial infarct size, histologic examination, MMP-2, MMP-9, and TIMP-1 protein expression were determined at the end of the experiment. RESULTS: Compared with I/R groups, CIP and NLIP reduced ST-segment elevation (P<0.01), decreased incidence and duration of ventricular arrhythmia (P<0.01) during ischemia, decreased CK-MB (P<0.05), and cTnI (P<0.01) activity, and increased SOD (P<0.05) activity after reperfusion. The myocardial infarct size (P<0.01) was significantly reduced, and cell injury was attenuated in the CIP and NLIP groups compared with the I/R group. MMP-2 and MMP-9 protein expression was significantly decreased in the CIP and NLIP groups (P<0.01), while TIMP-1 expression was significantly increased in the CIP and NLIP groups compared with the I/R group (P<0.01). CONCLUSION: Remote preconditioning via NLIP has late cardioprotection against myocardium I/R injury and has a similar magnitude of cardioprotection compared with CIP in rats.

Limited sampling strategy in rats to predict the inhibited activities of hepatic CYP3A.

The present study was undertaken in order to evaluate feasibility of a limited sampling strategy (LSS) to predict the systemic clearance of midazolam (MDZ), which is a hepatic CYP3A activity phenotyping probe. Groups of rats pretreated with or without serial doses of ketoconazole, which is a selective inhibitor on CYP3A, were used as training set. Linear regression analysis and a Jack-knife validation procedure were performed based on plasma MDZ concentrations at specific time points after sublingual vein injection of MDZ to establish the most informative LSS equations for accurately estimating the clearance of MDZ. Another group of rats in the same setting was used as the validation set to confirm the individual values of estimated clearance (Clest) that were derived from the predictive equations developed in the training set. LSS that were derived from one, two or three sampling times, namely 90 min, 60-90 min, 30-60-90 min and 30-60-120 min, gave the best correlation and acceptable errors between the values of observed clearance (Clobs) and Clest and were chosen to evaluate hepatic CYP3A activity. Our results supported the hypothesis that using limited plasma sampling is simpler than the usual method of estimating CYP3A phenotyping by predicting the systemic clearance of MDZ when the hepatic activity of CYP3A is reduced in the rat. This experimental design offers opportunities to reduce animal use in the study of drug metabolism.

[Study on ultrastructure of cardioprotection of ramipril against ischemia/reperfusion injury in diabetic rats].

AIM: To investigate the effects of ramipril on myocardial ischemia/reperfusion injury in diabetic rats, and to explore its mechanism according to the observation on myocardial ultrastructure. METHODS: Streptozotocin induced diabetic rats were divided randomly into three groups (n = 16): ischemia/reperfusion (I/R), ischemic preconditioning (IPC) and ramipril (RAM) group. Rats in RAM group were administered by RAM(1 mg x kg(-1) x d(-1)) orally for 4 weeks, the others were administered by normal saline. Then all rats were subjected to myocardial ischemia/ reperfusion injury. Rats in IPC group were preconditioned before ischemia. The ECG and the infarct size were examined. The changes of myocardial morphology were examined by light and electron microscopes. RESULTS: Compared with I/R group, the elevation of ST segment and the incidence of ventricular tachycardia and ventricular fibrillation during ischemia were significantly decreased, the infarct size at the end of reperfusion was remarkably reduced, the myocardial morphology were significantly improved, special structure of myofilaments and mitochondria remained clearly, blood vessels were unobstructed, injury of endothelium were decreased in PC and RAM groups. CONCLUSION: Ramipril administered for 4 weeks induces myocardial protection in diabetic rats, which is similar to that of IPC. The mechanism may be involved in protection of cardiocytes and mitochondria, and improvement of endothelial function.

[A limited sampling strategy of phenotyping probe midazolam to predict inhibited activities of hepatic CYP3A in rats].

The present study was to evaluate feasibility of a limited sampling strategy (LSS) in the prediction of inhibited hepatic CYP3A activity with systemic clearance of midazolam (MDZ), a hepatic CYP3A activity phenotyping probe. Rats were pretreated with a serial doses of ketoconazole, a selective inhibitor on CYP3A. Blood samples were collected and detected for MDZ at specified time points after intravenous injection of MDZ. Stepwise regression analysis and a Jack-knife validation procedures were performed in one group of rats as training set to establish the most informative LSS model for accurately estimating the clearance of MDZ. Another group of rats with same treatment was used as validation set to estimate the individual clearance based on predictive equations derived from the training set. Bland-Altman plots showed a good agreement between the systemic clearance calculated from DAS (CLobs) and corresponding parameter that was derived from three LSS models (CLest). LSS models derived from two or three sampling time points, including 60, 90 min, 30, 60, 90 min and 30, 60, 120 min, exhibited a good accuracy and acceptable error for estimating the CLobs of MDZ to evaluate hepatic CYP3A activity, especially the 60, 90 min LSS model is most accurate and convenient. The results supported that limited plasma sampling to predict the systemic clearance of MDZ is easier than the usual method for estimating CYP3A phenotyping when the hepatic activity of CYP3A is reduced in the rat. The present study provided theoretical basis and laboratory evidence for LSS to clinically evaluate metabolizing function of liver and