Real-time measurement of noradrenaline release in central nervous system / 生理学报

In order to investigate the central nervous mechanism and the diseases involved in catecholamine transmitter secretion, the dynamics of catecholamine release is studied in single cell, brain slice or in vivo. Noradrenaline is an important neurotransmitter and modulator in the central nervous system (CNS) and the peripheral nervous system (PNS). In the present paper, we first compared three real-time methods used to measure noradrenaline secretion in single cells (membrane capacitance, amperometry and confocal fluorescence microscopy imaging). Compared to the electrophysiological method and fluorescence microscopy, the basic usage of the carbon fiber electrode (CFE) in neuroscience research was presented as an example. Then, we presented a primary description of ion channels, including voltage-gated Na(+), K(+) and Ca(2+) channels in locus coeruleus (LC) neurons in rat brain slices. Finally, we presented example recordings of combined patch-clamp and amperometry measurements in LC neurons, indicating Ca(2+)-dependent quantal noradrenaline release following Ca(2+) influx through Ca(2+) channels.

Expression of annexin I in human pancreatic cancer and the influence of its down-regulation on biology of this cancer / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the expression of annexin in human pancreatic cancer and to elucidate its role in oncogenesis of pancreatic cancer.</p><p><b>METHODS</b>A pancreatic carcinoma cell line Suit-II with high-expression of annexin I gene was adopted. Three subtypes of annexin I -siRNA sequences and a non-related fragment were combined, and the eukaryotic expression vectors bearing siRNA fragments were constructed. Then they were transfected into pancreatic carcinoma cells to knock down the expression of annexin I by RNAi. After knocking down the expression of annexin I , the growth speed, cell cycling, morphological features and apoptosis of pancreatic carcinoma cells were examined by RT-PCR and MTT test.</p><p><b>RESULTS</b>When the expression of annexin I was blocked, the growth speed of pancreatic carcinoma cells was significantly decreased, the morphological features were changed and pronounced apoptosis occurred.</p><p><b>CONCLUSION</b>Annexin I can modulate pancreatic carcinoma cell cycle, promote the cell proliferation, increasingly stimulate the cell growth, and suppress the process of apoptosis in pancreatic carcinoma cells.</p>

A brief introduction to the secretion mechanism in immunocytes / 生理学报

Exocytosis is a vital function of many cell types including neuron, endocrine cell and immunocyte. Secretion in immunocytes involves a complex process of signal transduction, in which many factors still remain unknown. In the last 10 years, this area has become an international hot spot of investigation, resulting in many break-through progresses. This progress was made possible by combined efforts in molecular biology, cell biology and biophysics. This review focuses on notable new knowledge and some new techniques in functional study of secretion in immunocytes.

Properties of whole-cell potassium currents in mechanically dissociated Drosophila larval central neurons / 生理学报

By electrophysiological methods, cultured Drosophila embryonic and larval central neurons have been widely used to study ion channels, neurotransmitter release and intracellular message regulation. Voltage-activated K(+) channels play a crucial role in repolarizing the membrane following action potentials, stabilizing membrane potentials and shaping firing patterns of cells. In this study, a mechanical vibration-isolation system was used to produce a sufficient number of acutely dissociated larval central neurons, of which the majority were type II neurons (2~5 microm in diameter). Using patch clamp technique, the whole-cell K(+) currents in type II neurons were characterized by containing a transient 4-AP-sensitive current (I(A)) and a more slowly inactivating, TEA-sensitive component (I(K)). According to their kinetic properties, five types of whole-cell K(+) currents were identified. Type A current exhibited primarily fast transient K(+) currents that activated and inactivated rapidly. The majority of the neurons, however, slowly inactivated K(+) currents with variable inactivation time course (type B current). Type C current, being present in a small number of the cells, was mainly composed of noninactivating components. Some of the neurons expressed both transient and slow inactivating components, but the slowly inactivating components could reach more than 50% of the peak current (type D current). Type E current showed distinct voltage-dependent activation properties, characterized by its bell-shaped activation curve. Type E current was inhibited by application of Ca(2+)-free solution or 0.1 mmol/L Cd(2+). Moreover, this novel current ran down much more rapidly than other types. These results indicate that different K(+) channels, which have different kinetic and pharmacological properties, underlie the whole-cell K(+) currents in type II neurons of Drosophila larval central nervous system.