Volume-regulated anion conductance in cultured rat cerebral astrocytes requires calmodulin activity

We examined the calmodulin dependence of anion channel activation during hypo-osmotic swelling in rat cerebral astrocytes. Control cells bathed in iso-osmotic (290 mOsm) phosphate-buffered saline (PBS) and recorded using a patch electrode containing 140 mM KCl increased membrane conductance threefold over basal levels after 12 min in hypo-osmotic (200 mOsm) PBS. Cells injected with monoclonal anticalmodulin antibody demonstrated no increase in membrane conductance during a subsequent exposure to hypo-osmotic PBS. In contrast, cells iontophoretically injected with monoclonal antiglial fibrillary acidic protein antibody or with anticalmodulin antibody absorbed with an excess of free calmodulin demonstrated an increase in conductance during hypo-osmotic exposure similar to that of control cells. Conductance in iso-osmotic conditions was unchanged by antibody injection. Similar results were obtained when using patch electrode and bath solutions containing chloride as the only cell permeant ion, indicating a calmodulin-dependent anion current is activated with this degree of hypo-osmotic treatment. Western blots confirmed the specificity of the anticalmodulin and antiglial fibrillary acidic protein antibodies used in this study for proteins of 17 and 51 kD, respectively. In addition, in vitro studies demonstrated inhibition of the calmodulin-dependent activation of phosphodiesterase by the anticalmodulin antibody. Thus, binding of this antibody to calmodulin causes functional inhibition of calmodulin activity. No change in the intensity or cellular distribution of calmodulin immunostaining was observed during 30 min of hypo-osmotic exposure. However, increased immunostaining for activated calmodulin kinase IIalpha was observed after 10 min of hypo-osmotic exposure, suggesting initiation of calmodulin-dependent processes by cell swelling. The data indicate calmodulin activity is critical for activation of volume-regulated anion channels in rat cerebral astrocytes.     

Chronic hypoosmolality induces a selective decrease in magnocellular neurone soma and nuclear size in the rat hypothalamic supraoptic nucleus

The magnocellular neurones of the hypothalamo-neurohypophysial system (HNS) play a vital role in the maintenance of body homeostasis by regulating oxytocin (OT) and vasopressin (VP) secretion from the posterior pituitary. During hyperosmolality, OT and VP mRNA levels are known to increase by approximately two-fold, whereas during chronic hypoosmolality, OT and VP mRNA levels decrease to approximately 10-20% of basal levels. In these studies, we evaluated changes in cell size associated with these physiological conditions. Cell and nuclear sizes of neurones in the supraoptic nucleus (SON), the nucleus of the lateral olfactory tract (LOT) and the medial habenular nucleus (MHB) were measured from neurones identified by in situ hybridization histochemistry for beta(III)-tubulin mRNA, and measurements were made from OT and AVP magnocellular neurones in the SON after phenotypic identification by immunohistochemistry. Under hypoosmolar conditions, the cell and nuclear sizes of OT and VP magnocellular neurones decreased to approximately 60% of basal values, whereas cell and nuclear sizes of OT and VP neurones in hyperosmolar rats increased to approximately 170% of basal values. In contrast, neither hyperosmolality, nor hypoosmolality significantly affected cell and nuclear sizes in the LOT and MHB. These results confirm previous studies that showed that magnocellular neurones increase cell size in response to hyperosmolar conditions and, for the first time, demonstrate a marked decrease in cell size in the SON in response to chronic hypoosmolar conditions. These dramatic changes in cell and nuclear size directly parallel changes in OT and VP gene expression in the magnocellular neurones of the SON and, consequently, are consistent with the pronounced bidirectional changes in gene expression and cellular activity found during these osmotic perturbations. Our results therefore support the concept of global alterations in the synthetic activity of magnocellular OT and AVP neurones in response to extracellular osmolality.     

Expression of corticotropin releasing factor (CRF), urocortin and CRF type 1 receptors in hypothalamic-hypophyseal systems under osmotic stimulation

The expression of corticotropin releasing factor (CRF) and urocortin in hypothalamic magnocellular neurones increases in response to osmotic challenge. To gain a better understanding of the physiological roles of CRF and urocortin in fluid homeostasis, CRF, urocortin and CRF type 1 receptor (CRFR-1) gene expression was examined in the hypothalamic-hypophyseal system usingin situ and double-label in situ hybridization following chronic salt loading. CRFR-1 expression was further examined by immunohistochemistry and receptor binding. Ingestion of hypertonic saline by Sprague-Dawley rats for 7 days induced CRF mRNA exclusively in the oxytocin neurones of the magnocellular paraventricular nucleus (PVN) and the supraoptic nucleus (SON), but induced CRFR-1 mRNA in both oxytocin and vasopressin-containing magnocellular neurones. Hypertonic saline treatment also increased urocortin mRNA expression in the PVN and the SON. In the SON, urocortin was localized to vasopressin and oxytocin neurones but was rarely seen in CRF-positive cells. Changes in CRFR-1 mRNA expression in magnocellular neurones by hypertonic saline treatment were accompanied by changes in CRFR-1 protein levels and receptor binding. Hypertonic saline treatment increased CRFR-1-like immunoreactivity in the magnocellular PVN and SON, and decreased it in the parvocellular PVN. CRF receptor binding in the PVN and SON was also increased in response to osmotic stimulation. Finally, hypertonic saline treatment increased CRFR-1 mRNA, CRFR-1-like immunoreactivity and CRF receptor binding in the intermediate pituitary. These results demonstrate that the increase in the expression of CRF and urocortin message in magnocellular neurones induced by salt loading is accompanied by an increase in CRF receptor levels and binding in the hypothalamus and intermediate pituitary. Thus, CRF and urocortin may exert modulatory effects locally within magnocellular neurones as well as at the pituitary gland in response to osmotic stimulation.     

心脏病患者围手术期血浆胶体渗透压测定及临床意义

心脏手术期间患者血浆胶体渗透压(COP)的变化不可避免,但血浆COP对机体重要器官影响很大,直接测定血浆COP的技术引进后,使得临床连续测定血浆COP成为可能。本文就血浆COP的测定方法及临床意义进行综述。     

白芍总苷微孔渗透泵片中芍药苷的含量测定

目的建立用RP-HPLC法测定白芍总苷微孔渗透泵控释片中芍药苷含量的方法。方法采用Diamonsil C_(18)色谱柱(5μm,250mm×4.6mm),以甲醇-水-磷酸(体积比33:67:0.2)为流动相,检测波长230nm。结果芍药苷质量浓度在20～100μg/ mL范围内线性关系良好(r=0.9995),平均加样回收率100.6%(n=6)。结论本法准确、简便、专属性强,可用于白芍总苷微孔渗透泵控释片的质量控制。     

体外条件对不同类型灯盏花素缓控释制剂释放行为的影响

灯盏花素是从灯盏花中提取的黄酮类活性成分,包括灯盏乙素和灯盏甲素.灯盏乙素是其主要活性成分,在临床上被广泛用于治疗脑血管栓塞等症及心血管疾病等[1].随着中药现代化的兴起,将服用次数多、生物利用度低的灯盏花素普通制剂开发成新制剂已成为热点.以渗透泵和凝胶骨架技术为代表的缓控释制剂以其安全、顺应性好等优点发展快速.     

三七总皂苷微孔渗透泵控释片体外释放度研究

目的:研究三七总皂苷微孔渗透泵控释片的体外释放度。方法:考察不同溶出方法、搅拌桨速度和溶出介质对三七总皂苷微孔渗透泵控释片体外释药的影响。结果:溶出方法、桨叶转速以及溶出介质的pH值在3.5～7.6范围内时,对三七总皂苷渗透泵片体外释药行为无显著影响,但溶出介质的pH值在1.0时会严重影响渗透泵片药物的释放。结论:除酸性介质条件外,三七总皂苷微孔渗透泵片体外释药特征稳定。     

硫酸沙丁胺醇渗透泵控释片的人体药代动力学与生物利用度

目的:研究自制硫酸沙丁胺醇渗透泵控释片与进口控释片的人体药代动力学与生物利用度。方法:利用高效液相色谱荧光检测法,采用交叉实验设计对本品和进口硫酸沙丁胺醇控释片进行人体生物利用度对照研究。结果:硫酸沙丁胺醇控释片与进口硫酸沙丁胺醇控释片的血药浓度曲线下面积AUC 分别为(63.67 ±10.37)ng·h·mL^-1和(60.21 ±11.95) ng·h·mL^-1,最大血药浓度C_max 分别为(8.60 ±1.93) ng·mL^-1 和(8.20 ±1.40)ng·mL^-1,达峰时间T_max 分别为(6.3 ±1.0) h 和(6.8 ±1.3) h,多剂量给药达稳态时血药浓度波动系数FD 分别为1.09 ±0.23 和1.14±0.25。结论:经方差分析和双单侧检验,两种制剂生物等效。     

Enhanced Uptake of [3H] Spermidine by 9L Rat Brain Tumors After Direct Intratumoral Infusion of Inhibitors of Enzymes of the Polyamine Biosynthetic Pathway

We have been exploring the feasibility of delivering ionizing radiation to brain tumor cells by using tritium labeled polyamines. Polyamines are taken up preferentially by dividing cells and form noncovalent bonds with DNA. Their uptake can be enhanced by drugs which deplete endogenous polyamines. To test this in vivo, 9L cells were implanted in the striatal region of the brain in male Fisher 344 rats. Osmotic pumps containing trace amounts of [³H] spermidine or [³H] putrescine with either difluoromethylornithine or combinations of 3 inhibitors of enzymes of the polyamine biosynthetic pathway were implanted subcutaneously and were connected to intratumoral cannulas. After 14–16 days the brains were removed and sliced in the coronal plane. The diameters of the tumors were measured and tumor tissue was dissected from each slice, weighed and lysed for scintillation counting. It was found that difluoromethylornithine enhanced the uptake of [³H] putrescine while a combination of inhibitors of enzymes of the polyamine biosynthetic pathway enhanced the uptake of [³H] putrescine and [³H] spermidine producing a localized region of radioactivity in the 9L tumor. It is estimated that if the [³H] polyamines were at higher specific activity (commercially available), instead of the trace dose given here, the [³H] polyamine uptake would be sufficient to kill 9L tumor cells within a 2 to 3 week period.     

Hemolytic pattern of erythrocytes in the newborn measured by the coil planet centrifuge system and its relationship to neonatal jaundice

Dynamic osmotic fragility of erythrocytes in cord blood and its changes during the neonatal period were studied by means of a coil planet centrifuge system. The starting-point for hemolysis in the newborn become similar to that of adult blood after approximately a week, while the shift of the end-point to the adult range required one month or more.The percentage of fragile cord blood cells with a hemolysis starting-point above 110 m osmol and the maximum bilirubin level during neonatal period were examined. A high percentage of fragile cells was associated with high bilirubin levels, and when fragile cells comprised more than 7.0% of the total cord blood erythrocytes, the bilirubin level tended to rise above 15 mg/dl.This study was aided by a grant from the Ministry of Health and Wellfare of Japan for research on handicapped children, 1976