The Effects of Na~+/Ca~(2+) exchange (NCX) on the Repolarization of Canine Ventricular Myocyte-Potential Arrhythmogenic Effect of NCX during a Mis-matched Repolarization and Relaxation Xiamen Zhongshan Hospital, Xiamen Medical College, Xiamen University

The Effects of Na~+/Ca~(2+) exchange (NCX) on the Repolarization of Canine Ventricular Myocyte-Potential Arrhythmogenic Effect of NCX during a Mis-matched Repolarization and Relaxation Xiamen Zhongshan Hospital, Xiamen Medical College, Xiamen University@巩燕$Visiting scholar of cardiac arrhythmia research institute,university hospital of Oklahoma!U.S.A @王焱 @BELA Szabo$Basic cardiac research laboratory,cardiac arrhythmia research institute,university hospital of Oklahoma!…     

体表电位标测微机系统(Ⅰ型)

本系统的107个电极中,103个分布于胸、背部,1个为参考电极,1个为V_3,其余用于肢导。本系统除能绘出2、4、8ms任意间隔的103通道同步的体表等电位图,常规12导联和V_(7 9)心电图,胸、背部位的心电图外,还可记录R峰值等电位图,∑R,Q波等电位图,nQ30、40,极大、极小轨迹图等。     

Granulosa cell metabolism and the assessment of oocyte quality in IVF

The progesterone production of the granulosa cells of the cumulus– oocyte complex correlates very well with the cleavagepotential of embryos in an IVF system. The method is simpleand can be easily performed by any laboratory associated withIVF. Furthermore, high intratubal progesterone levels in theimmediate post-ovulatory period are probably important in prolongingthe intra-ampullary residence of the oocyte or embryo untilthe uterine endometnum is optimal for implantation.     

青滕碱对豚鼠心肌动作电位和收缩力的影响

青藤碱2.7μmol/L以上,呈浓度依赖性地降低豚鼠乳头肌收缩力,延长动作电位时程和有效不应期。小剂量时,青藤碱能降低动作电位0相上升最大速率;较大剂量时,动作电位幅度也降低。用TTX处理豚鼠乳头肌所致的慢反应电位,青藤碱能够抑制。此外,青藤碱能对抗乙酰胆碱缩短豚鼠左房肌动作电位时程的作用。结果提示:青藤碱对Na⁺,Ca²⁺和K⁺的跨膜转运均有抑制作用。     

Gating of the Auditory Evoked Potential in Children and Adults

Auditory evoked potentials were recorded from 163 subjects, aged IS months to 55 years. A conditioning-testing paradigm was used to assess sensory gating. In this paradigm, click stimuli are presented in pairs to the subjects with a 0.5-second intrapair interval. In normal adults, the first stimulus activates or “conditions” sensory gating mechanisms. The strength of these mechanisms is “tested” by the second stimulus, which produces a response whose amplitude is significantly suppressed. This aspect of sensory gating was not reliably observed in our subjects until age 18 years. Younger subjects varied widely in their ability to demonstrate sensory gating. Mean levels of suppression increased during late childhood and adolescence, with no relationship to other changes in evoked potential amplitude and latency. Sensory gating would appear to be a late developing aspect of human sensory physiology.     

Electrophysiologic mechanisms of ventricular arrhythmias

In this work the electrophysiologic mechanisms of ventricular arrhythmias have been briefly summarized. Ventricular arrhytmias can be caused either by pacemaker activity or by reentrant excitation. Enhancement of normal automaticy can generate a parasystolic rhythm in normal fibers. Abnormal automaticity may arise fom fibers in which maximum diastolic potential has been reduced by a variety of interventions. Triggered activity is caused by either an early (EAD) or delayed (DAD) afterdepolarization and requires a prior normal action potential for initiation. While there is growing evidence that EAD-induced triggered activity plays a significant role in the Long QTU syndrome and Torsade de Pointes, no clinical arrhythmias has definitely been ascribed to DADs, although DADs have been recorded in man after acute digoxin intoxication.Ventricular arrhytmias can be also caused by reentrant excitation, which can be subdivided into reflection or circus movement reentry (CMR). In the reflection model impulses in both directions are transmitted over the same pathway. In the CMR three models can be differentiated: the ring model, which requires a fixed anatomical obstacle; the figure-eight model and the leading circle model, where functional rather than fixed anatomical obstacles are involved.Abbreviations AV atrio-ventricular - CMR circus movement reentry - DAD delayed afterdepolarization - EAD early afterdepolarization - ECG electrocardiogram - LV left ventricle - MAP monophasic action potential - MF muscle fiber - PF Purkinje fiber - RV right ventricle - TdP Torsade de Pointes     

体感诱发电位在椎管内占位显微手术中的监测

目的　评价体感诱发电位 (SEP)在神经外科脊髓疾病显微手术中的监测作用 ,避免或减少医源性脊髓损伤。方法　 2 8例病人行术前、术中SEP全程监测 ,包括脊髓SEP(SSEP)及皮层SEP(CSEP) ,术中及时把监测信息反馈给术者。并将术中监测结果与术后疗效对照分析。结果　椎管内占位手术在行髓内肿瘤切除时最易引发SEP波幅降低及潜时延长。术中监测按Frankel分级D、E级患者波幅较基准电位下降不超过 50 % ,潜伏期延长不超过7% ;B、C级患者波幅较基准电位下降不超过 40 % ,潜伏期延长不超过 5 %。术后不会引起脊髓功能不可逆损害。结论　脊髓手术时行SSEP和CSEP联合监测可及时反映出脊髓功能的变化 ,提高术者术中操作的安全性 ,避免或减少术后并发症     

Vasopressin stimulation of NaCl transport in the medullary thick ascending limb of Henle's loop is decreased in aging mice

The maximal urinary osmolality that can be reached by the kidney is reduced with age. This may be due to impaired NaCl transport by the medullary thick ascending limb of Henle's loop, which is part of the renal concentrating mechanism and is modulated by antidiuretic hormone (ADH). We therefore tested in vitro a possible age-related change in the transport capacity and in the response of this nephron segment to ADH in young (1–2 months) and old (20–24 months) mice. The transepithelial potential difference (V _te) was significantly higher in young mice (+8.5±0.4 mV, n=13) than in old ones (+6.6±0.5 mV, n=17). Addition of 0.1 nmol.l^–1 ADH to the bath solution significantly increased V _te by 5.2±0.5 mV in the young and by 3.1±0.6 mV in the old animals. Application of dibutyryl-cAMP (0.1 mmol.1^–1) did not further increase the hormonal response in both groups. The ADH-mediated increase in the corresponding equivalent short-circuit current (I _SC = V _te/R_te) was twice as great in young mice as in old, indicating that the stimulation of NaCl transport by ADH across the medullary thick ascending limb is significantly reduced with age. These results suggest that the previously reported age-related defect in the urinary concentrating ability of the kidney is partly due to a decreased response of the medullary thick ascending limb to ADH.     

Dopamine antagonists reduce spontaneous electrical activity in cultured mammalian neurons from ventral mesencephalon

Mammalian neurons from ventral mesencephalon (VM) were grown in primary dissociated cell (PDC) culture. These neurons are predominantly non-dopaminergic. Many of these non-dopaminergic neurons have dopamine agonist and antagonist binding sites. Intracellular recordings were obtained from these neurons. When bathed in phosphate-buffered saline (PBS) solution they generated action potentials spontaneously. However, in the presence of haloperidol dissolved in PBS solution, the percentage of neurons which generated action potentials spontaneously was reduced in a dose-dependent manner (1–10 μM). This response was also obtained with (+) butaclamol (1 μM) but not with (−) butaclamol (1 μM). This neuroleptic inhibition of spontaneously generated action potentials was specific for neurons in PDC cultures of VM since neurons in PDC cultures of spinal cord did not demonstrate this phenomenon.     

Neuroplastic effects of neonatal capsaicin on barrel cortex of adult rat. An electrophysiological and autoradiographic study

Capsaicin (50 mg/kg s.c./25 μl) was administered to rats on the 2nd and 5th days after birth. The animals were raised, and from the age of 3 months the properties of the evoked activity were tested in the contralateral barrelfield. This neonatal capsaicin treatment was found to induce profound changes in the responsiveness of the barrel cortex in the adult rats: (1) the receptive field of the neurons in the Cl barrel was expanded; units within a particular barrel were driven by a significantly larger number of vibrissae than in the controls. (2) The rate of discharge evoked by the related vibrissa deflection was enhanced, while (3) the angular sensitivity of the neurons was decreased. (4) The most prominent change in cortical activity was observed by autoradiography: capsaicin-treated rats exhibited an enhanced labelling of different types of neurons throughout the hemisphere (surpassing the cortical representation of stimulated vibrissae). The present observations indicate that neonatal capsaicin affects the functional activity of the rat somatosensory cortex. It is suggested that unmyelinated sensory afferents play a role in the development of the rat somatosensory system.