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Objective: To investigate the effect of ghrelin on duodenal migrating myoelectric complex (MMC) in rats with chronic renal failure (CRF)., Methods: Thirty healthy male SD rats were randomly assigned into sham-operated group (n=6) and CRF group (n=24), and the latter group was divided into 4 subgroups according to ghrelin doses administered with or without pretreatment with the receptor antagonist D-Lys(3)-GHRP-6. After a 18-h fasting, the rats with or without pretreatment with D-Lys(3)-GHRP-6 were given subcutaneous injections of ghrelin at different doses to observe the changes in duodenal MMC recorded using a multi lead physiological recording system., Results: Ghrelin significantly increased the MMC cycle duration and dose-dependently enhanced the frequency, amplitude and percentage of phase III MMC cycle. This effect was inhibited by the pretreatment with ghrelin receptor antagonist D-Lys(3)-GHRP-6., Conclusion: Ghrelin can promote gastrointestinal motilities of rats with CRF, and the receptor of ghrelin can regulate the activity of MMC.

Large-scale and highly oriented single-crystalline hexagonal Cu(2)O nanotube arrays have been successfully synthesized using a two-step solution approach, which involves the electrodeposition of oriented Cu(2)O nanorods and a subsequent dissolution technique along the c axis to form a tubular structure. Herein, NH(4)Cl was found to be an effectual additive, and it can successfully realize the dissolution process of Cu(2)O from nanorods to nanotubes. The dissolution mechanism of Cu(2)O from nanorods to nanotubes was illustrated in detail. These prepared Cu(2)O nanotube arrays were characterized by SEM, EDS, XRD, XPS, and TEM. The photoluminescence (PL) spectrum of Cu(2)O nanotube arrays was also measured, and it shows there is a greater fraction of copper or oxygen vacancies in these prepared Cu(2)O nanotubes. Finally, the applications of Cu(2)O nanotube arrays for gas sensors were investigated in this paper.

The objective of this study was to investigate the molecular basis of the inferior nodal extension (INE) in the atrioventricular junctional area that accounts for arrhythmias. The INE was separated from the adult rat heart by laser capture microdissection. The mRNA expression of ion channels was detected by quantitative real-time PCR. Hierarchical clustering was used to demonstrate clustering of expression of genes in sections. The mRNA expression of HCN4, Ca(v)3.1 and Ca(v)3.2 was high in the INE, atrioventricular node and sino-atrial node, and that of Ca(v)3.2 high in Purkinje fibres. Although the expression of HCN1 and Ca(v)1.3 was low in the rat heart, it was relatively higher in the INE, atrioventricular node and sino-atrial node than in right atrial and right ventricular (working) myocytes. Both HCN2 and Ca(v)1.2 were expressed at higher levels in working myocytes than in nodal tissues and in the INE. Hierarchical clustering analysis demonstrated that the expression of the HCN and calcium channels in INE was similar to that in the slow-response automatic cells and different from that in working myocytes and Purkinje fibres. The expression of HCN and calcium channels in the INE of the adult rat heart is similar to that of slow-response automatic cells and provides a substrate for automatic phase 4 depolarization in cells.

Aim: To investigate whether aspirin is able to augment gemcitabine-induced cytotoxicity in human pancreatic cancer cells., Methods: Two gemcitabine-insensitive human pancreatic cancer cell lines, PANC-1 and Capan-1, were used. Cells were treated with either aspirin or gemcitabine alone or both of them. Cell growth and apoptosis were determined by MTT assay, Annexin V or Hoechest 33258 staining. Cell cycle distribution was examined by flow cytometry. Western blot with specific phosphorylated protein antibodies was used to detect the activation of protein kinase. RT-PCR and Western blot were applied to assess the transcription and protein level for cyclin D1 and Bcl-2., Results: Aspirin alone significantly inhibits the proliferation of PANC-1 cells by causing cell cycle arrest at G(1) phase. Aspirin potentiates the anti-survival effect of gemcitabine as well as its pro-apoptotic effect in PANC-1 cells, although aspirin per se does not trigger apoptosis. Aspirin inhibits GSK-3beta activation and suppresses the expression of its downstream gene products (cyclin D1 and Bcl-2), which are implicated in proliferation, survival and chemoresistance of pancreatic cancer. The effects of aspirin on Capan-1, were similar to that on PANC-1., Conclusion: Our results suggest that aspirin inhibits the proliferation of gemcitabine-resistant pancreatic cancer cells and augments the antisurvival effect of gemcitabine, probably by suppressing the activity of GSK-3beta and its downstream gene products.

Objective: To explore the electrophysiologic characteristics of Ito in myocytes from cardiac Koch triangle., Methods: Patch clamp technique was employed to investigate the I-V and D-V relation, steady-state activation and inactivation kinetics of Ito from myocytes in Koch triangle of rabbit hearts., Results: (1) The maximum peak current (pA) and peak current density (pA/pF) at +20 mV in PC (pacing cell), TC (transitonal cell) alpha,beta, AC (atrial cell) and PL (purkinje-like cell) cells were different from each other (P < 0. 05); The cells also had different current density (P < 0.05) except between TCalpha, TCbeta and PL cells (P > 0.05). (2) The half activation potential (V(mIto1/2), mV) of steady state activation among PC, TCalpha, TCbeta, AC and PL were significantly different (P < 0.05); The paired comparison between TCalpha and TCbeta, AC and PL, and TCbeta and PC showed significant difference (P < 0.05); but the differences between TCa and PC, TCbeta and AC, and TCbeta and PL were not significant (P > 0.05). (3) The half inactivation potential (V5(hIto1/2), mV) of steady state inactivation between TCalpha and PC, TCa and PL, TCbeta and PC, and TCbeta and PL demonstrated significant differences(P < 0.05). The differences of K(hIto) between TCalpha and TCbeta, PC and PL, TCbeta and PC, and AC and PL were significant (P < 0.05)., Conclusions: Ito of cardiac cells from Koch triangle in rabbit hearts are heterogeneous, but relatively specified and distributed in different groups.

Objective: To quantitatively detect the expression of connexins (Cx) mRNA in the posterior nodal extension (PNE) of adult rat heart and understand the relationship between Cx expression and atrial ventricular nodal reentrant tachycardia (AVNRT)., Methods: PNE was separated from adult rat heart by means of laser microdissection (LCM), and the cells were also isolated from the atrioventricular node (AVN), sinoatrial node (SAN), Purkinje fiber (PF), right atrium (RA) and right ventricle (RV), to serve as the controls. The Cx mRNA level was detected in these cells with quantitative real-time PCR (QRT-PCR)., Results: The cells were successfully isolated from the PNE and other regions of adult rat heart, where heterogeneous expression of the 3 Cx isoforms (Cx43, Cx45, and Cx40) were observed. Cx45 mRNA showed higher expression in the PNE than in the working myocardium, whereas Cx43 mRNA level was about 25 times higher (P<0.05) in the working myocardium and 18 times higher (P<0.05) in the PF than in the PNE. In the PF, Cx40 mRNA level was proximately 6.8 times (P<0.01) as much as that in the PNE. Cx expression in the PNE was, however, similar to that in the SAN and AVN., Conclusion: Cx mRNAs exhibit heterogeneous expression in the PNE to allow the formation of the slow pathway. In addition, Cx expression in the PNE is very different from that in the adjacent myocardium, resulting in conduction discontinuity at the cellular junction, where, on certain occasion, unidirectional block may occur to cause AVNRT.

Objective: To use the laser capture microdissection (LCM) to isolate the pure atrial cells from heart. To extract tiny amount RNA and amplify the genes of beta-actin and GAPDH., Methods: First, the prepared sample RNA was extracted and verified. Second, the frozen sections were scraped after haematoxylin-eosin staining, and then the RNA of scraped tissues was extracted and verified. Last, the tiny amount RNA was extracted from atrial cells captured by LCM, and the genes of beta-actin and GAPDH were amplified by reverse transcriptase polymerase chain reaction (RT-PCR)., Results: The atrial cells isolated with LCM had clear morphology after quick staining. The high quality RNA was extracted from LCM sample and scraped tissues, of which A260/A280 was 1.9-2.0. And 18S rRNA and 28S rRNA were seen distinctly on the gel of RNA formaldehyde denaturing gel electrophoresis, which indicated that RNA didn't degrade before cells captured. Too small amount of RNA extracted from captured cells was below the detectable limit of gel electrophoresis or ultraviolet spectrophotometer. Bands of 300 bp and 357 bp could be amplified by RT-PCR from tiny amount RNA., Conclusion: Highly pure atrial cells could be obtained by LCM. Tiny amount RNA of captured atrial cells could be extracted and amplified with genes of beta-actin and GAPDH.

Objective: To investigate the expression and distribution of L-type calcium channel alpha1C subunits in adult rat heart., Methods: HE staining was applied on the frozen sections of adult rat heart to identify the sinoatrial node (SAN), atrioventricular node (AVN), and posterior nodal extension (PNE). The protein expression of L-type calcium channel alpha1C in adult rat heart and its cellular localization were examined by Western blotting and immunohistochemistry, respectively., Results: L-type calcium channel alpha1C subunit was immunolocalized on the membrane of the myocardial cells, and its expression increased gradually in the SAN, AVN, PNE, right atrium and right ventricle. The protein level of L-type calcium channel alpha1C in the AVN was similar to that in the PNE (P>0.05), and its level in the right atrium and ventricle were significantly higher than those in the SAN and AVN (P<0.01). The results of Western blotting were well consistent with the results of immunohistochemistry., Conclusion: The expression of L-type calcium channel alpha1C subunit may play a role in the electrophysiological functions of the heart.

The pancreatic polypeptide response to a meal depends on various mechanisms, which are only partly understood. The aim of this study was to define whether humoral factors and nutrients which modulate postprandial gastric acid secretion play a role in the regulation of pancreatic polypeptide secretion. Our study was performed in the cat, a species in which pancreatic polypeptide release has never been explored. The animals were provided with a gastric fistula and a Heidenhain pouch and received, in a random order, mixed liver (50 g) per os or different nutriments which were introduced directly into the gastric fistula in identical final volumes: 50 g mixed liver; 1.5 to 12 g oligopeptides; or 2 g of triglycerides or glycogen. Acid output and pancreatic polypeptide secretion were measured over 150 min. In the cat as in dog and man, a mixed meal induced a five to ten-fold increase of plasma pancreatic polypeptide. The protein fraction of the meal was the most potent stimulus for release of this peptide and the pancreatic polypeptide response to protein seemed to be dose-related. The lipid and carbohydrate components of the meal were only weak stimulants. In the cat, a central vagal stimulation is effective on pancreatic polypeptide release, as on gastric acid secretion, since 2-deoxyglucose stimulated both secretions (about 15 p. 100 of maximal response to a meal). The integrated pancreatic polypeptide release and the Heidenhain pouch acid secretion in response to nutriments were correlated during the 30-120 min period.(ABSTRACT TRUNCATED AT 250 WORDS)