AIM: To investigate the effect of prostanoid DP receptors (DPR) on sleep-wake regulation in mice. METHODS: Under pentobarbital anesthesia, mice were chronically implanted with electroencephalogram (EEG) and electromyogram (EMG) electrodes for polysomnographic recordings. The spontaneous sleep-wake cycles were monitored continuously by EEG/EMG recording system for 24 h beginning at 800 p.m. and analyzed by SLEEPSIGN software in DPR knock out (KO) and wild type (WT) mice. RESULTS: DPR-KO mice exhibited a similar circadian rhythm of sleep-wake cycles to WT mice. The amounts of rapid eye movement (REM) sleep or non-REM (NREM) sleep during both the light and dark periods were identical between the DPR-KO and WT mice. Whereas, an increase in the episode number of wakefulness and a shortage in the duration of NREM sleep were found in DPR-KO mice during the light period compared with WT mice. Moreover, DPR-KO mice showed lower activity in delta-wave component in NREM sleep and higher activity in theta-wave component in REM sleep than WT mice. CONCLUSION: DPR plays a crucial role in mediating the prostaglandin D2-induced sleep. Deficiency of DPR results in the low intensity and fragmented diurnal NREM sleep and the high vigilance REM sleep, with the normal circadian rhythm of sleep in mice.

AIM: To investigate the apoptosis of a vascular smooth muscle cell line A10 caused by mild K+ depolarization. METHODS: Apoptosis was evaluated by nuclear staining, DNA fragmentation gel electrophoresis and propidium iodide-stained flow cytometry. Mitochondrial transmembrane potential (Δψm) was measured by flow cytometry. RESULTS: K+ depolarization caused dose correlated A10 cells apoptosis; nifedipine, BAPTA/AM, ryanodine inhibited the cytotoxic effect of K+ completely.The combination use of nifedipine and cyclosporin A made it clear that mitochondria was involved in the apoptosis of A10 cells,and Δψm measurement further confirmed this speculation; A10 apoptosis caused by K+ depolarization was not influenced by heparin or Zn2+,a effective capacitative calcium entry(CCE) blocker. CONCLUSION: Ca2+ entry through voltage-dependent ca channels increases intracytoplasm Ca2+, then triggers further Ca2+ release from endoplasmic reticulum via ryanodine receptor, and the microdomains of elevated intracytoplasm Ca2+ are sensed by adjacent mitochondria, which ultimately lead to cell apoptosis.

AIM: To investigate the anticoagulant effect of pravastatin and low molecular weight heparin (LMWH), as well as their combination, over time, in a rat model of experimental nephrotic syndrome. METHODS: Healthy SD male rats were chosen randomly to perform nephrotic syndrome models by single injection of adriamycin via tail vein, the matched normal control rats received single injection of equivalent 0.9% sodium chloride instead. After 14 days, the models were set up and randomized into model control group, pravastatin group (pravastatin 2 mg·kg-1·d-1 gavage once a day), LMWH group(LMWH 200 U·kg-1·d-1 intraperitoneal injection once a day) and combined treatment group(pravastatin 2 mg·kg-1·d-1 gavage+ LMWH 200 μ·kg-1·d-1 intraperitoneal injection), then all rats underwent measuring proteinuria every two weeks and fibrinogen, antithrombinⅢ(ATⅢ), D-dimer, platelet count, serum total protein and serum albumin after 4 weeks of treatment. RESULTS: The concentration of fibrinogen and D-dimer in model group was higher significantly than that in control group, and the level of ATⅢ was lower remarkably than that in control group, but platelet count had no obvious change; Compared with model group, pravastatin could increase the level of ATⅢ and decrease the concentration of D-dimer, but the concentration of fibrinogen and platelet count did not change obviously; LMWH and combined treatment could also decrease level of D-dimer, but had no great effects on ATⅢ, fibrinogen and platelet count; all treatment group had no obvious change of serum total protein and serum albumin. CONCLUSION: Adriamycin-induced nephrotic syndrome rat models have hypercoagulability and pravastatin can increase the level of ATⅢ.

AIM: To improve the prevent efficacy of peptide p277 in autoimmune diabetes. METHODS: The recombinant expression plasmid pET28-Hsp65-6×p277 was constructed by inserting 6×p277 which were amplified by PCR into the vector pET28-Hsp65. The plasmid pET28-Hsp65-6×p277 was transformed into E.coli BL21 (DE3) and the fusion protein (Hsp65-6×p277) was expressed effectively as soluble protein after inducing by lactose. The fusion protein was purified and then used to immunize 4-week old female NOD mice with three times of i.n. inoculations in the absence of adjuvants. Serum samples from the immunized mice were collected at monthly interval. The concentrations of blood glucose and antibodies were measured by automatic analyzer. RESULTS: Administration with the Hsp65-6×p277 to NOD mice could prevent the development of diabetes. CONCLUSION: The fusion protein Hsp65-6×p277 might be further developed to a vaccine against insulin-dependent diabetes mellitus.

AIM: To investigate the pharmacokinetic properties and bioequivalence of nifedipine sustained-release tablets after multiple doses administration in healthy volunteers. METHODS: Twenty two male healthy volunteers were enrolled in a randomized two-way crossover design with multiple doses (20 mg·d-1×7 d) study. Nitrendipine was used as the internal standard and the concentrations of nifedipine in plasma were determined by HPLC-APCI-MS. The pharmacokinetic parameters were calculated and the bioequivalence were compared by DAS (ver 1.0) program. RESULTS: The pharmacokinetic parameters of test and reference preparations were as follows: Cmax (52.5±27.4) and (54.0±31.2) ng·ml-1;Cmin (5.4±4.1) and (6.2±5.9) ng·ml-1;Cav (16.8±9.2) and (19.3±12.4) ng·ml-1;Tmax (3.7±0.9) and (4.1±1.1) h;t1/2 (8.9±4.9) and (8.5±3.1) h;AUC0-τ (403.4±221.0) and (461.9±296.6) μg·h·L-1, AUC0-36h (444.4±256.1) and (503.1±330.9) ng·h·ml-1;AUC0-∞ (482.1±268.9) and (542.3±348.4) ng·h·ml-1;DF (299.8±117.7)% and (279.2±97.5)%, respectively. There were no significant differences (P>0.05) in Tmax, Cmax, Cmin, Cav, DF, AUC0-τ, AUC0-36h, AUC0-∞ and t1/2 between the two preparations. The relative bioavailability of test tablets was (100.6±38.6)%. CONCLUSION:The test and reference preparations were bioequivalence.

AIM: To investigate the effect of paclitaxel on the quantitative growth of rabbit's vascular smooth muscle cells (SMCs) and endothelial cells (ECs) and their relationship in vitro. METHODS: An ex vivo model of endothelium repair was developed in which rabbit's SMCs were inoculated in the upper chamber and rabbit's ECs in the lower chamber of a co-culture system. 3 H-TdR incorporation and cell counting were used to determine the effect of paclitaxel on the quantitative proliferation of rabbit's vascular ECs and SMCs. The migration rate was analyzed to determine the effect of paclitaxel on the migration of rabbit's vascular ECs and SMCs. The IC50 of paclitaxel on ECs and SMCs was calculated. RESULTS: The 3 H-TdR incorporation, cell counting and migration of rabbit's vascular SMCs were inhibited by paclitaxel of 1 nmol·L-1-1 μmol·L-1 in a concentration-dependent manner (n=6, P<0.01). The 3 H-TdR incorporation and cell counting of rabbit's vascular ECs were inhibited by paclitaxel of 10 nmol·L-1-1 μmol·L-1 and migration by paclitaxel of 1 nmol·L-1-1 μmol·L-1 in a concentration-dependent manner (n=6, P<0.01). The 3 H-TdR incorporation assay resulted in the IC50 of 10.09±0.47 nmol·L-1 on SMCs and 19.06±0.35 nmol·L-1 on ECs proliferation. The migration assay resulted in the IC50 of 9.16±0.54 nmol·L-1 on SMCs and 5.37±0.51 nmol·L-1 on ECs migration. Paclitaxel (10 nmol·L-1, 20 min) inhibited SMCs growth of the confluent ECs group during the observed period. However, increased SMCs growth was observed in the proliferative ECs group 10 days after paclitaxel intervention. CONCLUSION: Paclitaxel inhibits not only SMCs but also ECs growth in rabbit's vascular. The delayed SMCs proliferation is closely related with the delayed ECs regeneration induced by paclitaxel.

AIM:To establish an LC-MS method for determining the concentrations of loratadine (LOR) in human plasma and to evaluate its pharmacokinetic characteristics. METHODS: A ZORBAX Eclipse XDB-C8 (5 μm, 150 mm×4.6 mm) column was used, atmospheric pressure electronic spray ionization (AP-ESI) and ion mass spectrum (m/z) of 388.2 (M+H)+ were selected to quantify LOR, and 275.1 (M+H)+ for ropivacaine (internal standard, IS). RESULTS: The linear range of LOR standard curve was 0.5-50 ng·ml-1, and the determination limit was 0.5 ng·ml-1. The pharmacokinetic parameters of LOR after a single dose of 20 mg tablet (T1), capsule (T2) and reference (R) were as follows, the half life (t1/2) 13.52±1.35, 13.14±0.98 and 14.00±1.25 h, the time to peak concentration (Tmax) 1.24±0.06, 1.18±0.12 and 1.17±0.12 h, the peak concentration (Cmax) 21.72±7.70, 21.49±8.34 and 20.50±8.65 ng·ml-1, the area under time-concentration curve (AUC0-48 and AUC0-∞) 137.24±47.84 and 146.61±51.03 ng·ml-1·h, 139.65±45.69 and 148.04±48.10 ng·ml-1·h, 134.19±49.03 and 143.70±52.08 ng·ml-1·h, the relative bioavailability of LOR tablet and capsule were (105.49±8.08)% and (102.90±10.02)%, respectively. CONCLUSION: The LC-MS method for determining the concentration of LOR in human plasma is sensitive and accurate and can be used for LOR bioavailability and pharmacokinetic studies. LOR tests and reference are bioequivalent.

AIM: To determine the concentration of escitalopram in human plasma by HPLC-MS/MS and investigate the pharmacokinetics of escitalopram. METH-ODS: The method involved protein precipitation with methanol. The chromatographic separation was achieved within 6.0 min by using methanol-water with 15 mmol·L-1 ammonium acetate-formic acid (72:28:O.1, v/v/v) as mobile phase and a Lichrospher CN 150 mm×4.6 mm analytical column. The analytes were detected using an electrospray ionization tandem mass spectrometry in SRM mode. Detection of the ions was performed by monitoring the transitions of m/z 325.0 to 234.0 for escitalopram and m/z 409.1 to 238.1 for amlodipine (intemal standard), respectively. RESULTS:The standard curve was linear ( r = 0. 999) over the concentration range of 0.20 - 50.00 ng· ml- 1. Accuracy and precision were below the acceptance limits of 15%. The recoveries of escitalopram ranged from 96.0% to 103.6%. The lower limit of quantification for escitalopram was 0.20 ng· ml-1 using 200 μl plasma sample.The pharmacokinetic parameters of escitalopram after a single oral dosing of escitalopram oxalate tablet (10 rog)to ten healthy male volunteers were achieved. The Cmax, Tmax, AUC0-t, AUC0-∞, t1/2 and Ke of escitalopram were 9.21±2.10 ng·ml-1 , 3.75±1.04 h, 514.6±152.3 ng·h·ml-1 ,540.5±162.3 ng·h·ml-1 , 34.06±7.71 h and 0.021±0.004 h-1,respectively. CONCLUSION:The determination of concentration of escitalopram in human plasma by HPLC-MS/MS method was repid, sensitive and reliable. It can be used for clinical pharmacokinetic study of escitalopram.

AIM: To study the bioequivalence of piracetam tablets in Chinese healthy volunteers. METH-ODS: Twenty volunteers were randomly divided into two groups (test and reference), with double cross-over design and single-dose oral administration. The concentration of piracetam in serum was determined by HPLC. The main pharmacokinetic parameters were calculated and the bioequivalence was evaluated with DAS2.0 practical pharmacokinetics program. RESULTS: The pharmacokinetic parameters of piracetam tablets were as follows: t1/2 were 5.50±1.48 and 4.29±1.00 h, Cmax were 21.47± 6.27 and 20.96±5.10 mg·L-1, Tmax were 0.70±0.46 and 0.66± 0.36 h, AUC0-24h were 93.44± 16.61 and 96.67± 18.50 mg·h·L- 1. The relative bioavailability of the test preparation was 99.8%± 22.7%. CONCLU-SION: The test and reference preparations were bioequivalent and may be prescribed interchangeably.

AIM: To study the effect of Lomerizine on the activity of P-glycoprotein (P-gp) in the bloodbrain barrier(BBB) and search for novel effective P-gp inhibiting agent against multidrug resistance. METH-ODS: Rhodamine123 (Rh123) was used to examine the activity of P-gp and RT-PCR to study the mdr mRNA expression in cultured rat brain microvessel endothelial cells (RBMECs). RESULTS: Lomerizine could increase the cellular Rh123 in RBMECs in a concentration-dependent manner. RT-PCR indicated that lomerizine could not down-regulate the expression of mdr mRNA. CONCLU-SION: Lomerizine can reverse multidrug resistance in the blood-brain barrier by inhibiting the activity of P-gp.KEY WORDS lomerizine; P-glycoprotein; bloodbrain barrier; RT-PCR