心房钠尿肽对血管紧张素II促血管平滑肌细胞增殖...

By means of technique of cell culture, 3H-thymidine incorporation and dot blot, it was demonstrated that angiotensin II (AGT II) stimulated proliferation and c-fos oncogene expression in cultured SHR vascular smooth muscle cells (VSMC) in a dose-dependent manner. This effect of AGT II was significantly inhibited by co-incubation with ANP. The results suggest that proliferation of VSMC is regulated by some interaction between AGT II and ANP.     

刺激隐神经中C类纤维诱发的小脑浦肯野细胞简单...

Simple spike of cerebellar Purkinje cells (PC-SS) was recorded with microelectrode. In the NCCVF (normalized cross-covariance function) histogram, spontaneous PC-SS does not show obvious peak. When the saphenous nerve is stimulated at lower intensities, which elicits the A-fiber input only, the discharge response (A-CED) consists of an early component with a latency of 16.7 +/- 0.9 ms and a late component with a latency of 270.8 +/- 12.8 ms. After A-fibers are blocked selectively by polarizing current, the stimulation at a suprathreshold strength for C-fiber evokes a characteristic response (C-CED) with a latency of 142.4 +/- 4.3 ms. However, the C-CED can not be evoked by the inputs of A- and C-fiber simultaneously. In NPSDF histogram, the spontaneous activities of PC-SS can be divided into two groups, the high and the low peak group. The high peak group (n = 15) has a peak energy value of 15.7 +/- 4.7 x 10(-3) and peak frequency of 4.07 +/- 1.69 Hz. A-fiber input causes an increase of the peak value, while C-fiber input causes a decrease. The low peak group (n = 16) has a peak energy value 8.4 +/- 1.4 x 10(-3) and peak frequency of 3.67 +/- 2.90 Hz. Both A-fiber and C-fiber inputs cause an increase of the peak value, but the effect of A-fiber input was more prominent. The results show that the pure C-fiber input can reach the cerebellar PC and elicit characteristic simple spike response.     

自发性高血压大鼠血管α1肾上腺素受体亚型的改变

本工作在离体与整体条件下比较易卒中型自发性高血压(SHRSP)大鼠与WKY大鼠血管中α_1受体的两种亚型。在离体灌流的主动脉、肾动脉与肠系膜动脉,50μmol/L氯甲基可乐定(CEC)预温育30min可使α_1受体激动时引起的最大收缩张力在SHRSP与WKY大鼠分别降为对照时的31.4±8.3％与35.2±2.9％,68.4±8.2％与80.1±7.3％,68.4±6.3％与55.4±7.0％,两者间均无显著性差别。但10μmol/L硝苯吡啶对α_1受体收缩效应的阻断作用则在SHRSP大鼠大大超过WKY大鼠,最大收缩张力分别降为对照时的3.1±1.5％与56.5±4.8％(P<0.01),9.0±4.1％与23.6±3.5％(P<0.05),5.9±2.5％与28.0±0.8％(P<0.01)。整体动物实验也显示硝苯吡啶的降血压作用及对苯肾上腺素升血压效应的阻断作用在SHRSP大鼠都较WKY大鼠显著增强。离体主动脉a_1受体激动时的快速相与持续相收缩均主要由α_(1B)亚型激动引起,硝苯吡啶对快速相收缩的阻断作用在SHRSP与WKY大鼠无显著性差别,但对持续相收缩的阻断作用则在SHRSP大鼠显著强于WKY大鼠。上述结果提示SHRSP大鼠血管α_1受体两种亚型的分布没有显著改变,但α_(1B)受体激动时继发性细胞外Ca~(2+)进入的途径由非双氢吡啶敏感性钙通道转变为双氢吡啶敏感性钙通道。     

刺激隐神经中C类纤维诱发的小脑浦肯野细胞简单锋电位反应

用玻璃微电极记录了猫小脑浦肯野细胞的简单锋电位(PC-SS)。在标准化互协方差函数图中,PC-SS自发放电无明显波峰;弱刺激隐神经只引起A类纤维传入时,PC-SS出现A类诱发放电反应(A-CED),它包括潜伏期为16.7±0.9ms的早反应和270.8±12.8ms的晚反应。用极化电流选择性阻滞A类纤维传导后,强刺激只引起C类纤维单独传入时,出现潜伏期为142.4±4.3ms的C类诱发反应(C-CED)。强刺激同时引起A类和C类纤维传入时,只出现A-CED而不出现C-CED。按标准化功率谱密度函数分析,PC-SS自发放电可分为两种类型。一类为高峰型,最大能量峰值平均为15.7±4.7×10~(-3),峰频为4.07±1.67Hz;刺激A类纤维使峰值增大,而刺激C类纤维却使峰值减小。另一类为低峰型,峰值为8.4±1.4×10~(-3),峰频为3.67±2.90Hz。刺激A类和C类纤维均使峰值增大,前者增大更多,但峰频均无显著性变化。上述结果表明,C类纤维传入可以到达小脑浦肯野细胞,引起特异的PC-SS放电反应。     

植物细胞在离体培养条件下的决定问题

“决定”(Determination)这一术语来自动物胚胎发育生物学,意指胚胎某一区域的组织或细胞只能向某一特定方向分化的发育状态。决定与否以及决定的程度必须用离体培养或异位移植的方法来测定。“决定”作为发育生物学上的一种现象,同样存在于高等植物中,如茎生长点的成花决定和