Inhibition of Na+,K+-ATPase by Ouabain Opens Calcium Channels Coupled to Acetylcholine Release in Guinea Pig Myenteric Plexus

Abstract: Ouabain, an Na⁺,K⁺-ATPase inhibitor, increases the release of acetylcholine (ACh) from various preparations in a Ca²⁺-independent way. However, in other preparations the release of ACh evoked by ouabain is dependent on the presence of extracellular calcium. In the present study, we have labeled the ACh of myenteric plexus longitudinal muscles of guinea pig ileum and compared the effect of calcium channel blockers on ouabain-evoked release of [³H]ACh. Release of [³H]ACh evoked by ouabain is dose dependent and decreased markedly in the absence of calcium or in the presence of cadmium, a nonspecific calcium channel blocker. N-type calcium channel blockage by the ω-conotoxins GVIA (selective N-type calcium channel blocker) and MVIIC (a nonselective calcium channel blocker) inhibited by 45 and 55%, respectively, the release of [³H]ACh. L-type calcium channel suppression by low concentrations of verapamil, nifedipine, and diltiazem had no effect on the release of [³H]ACh. The release of transmitter was also not affected significantly by nickel, a T-type calcium channel blocker. In addition, ω-agatoxin-IVA, at concentrations that block P- and Q-type calcium channels, did not affect significantly the release of [³H]ACh. Thus, extracellular Ca²⁺ is essential for the release of ACh induced by ouabain from guinea pig ileum myenteric plexus. In this preparation, the N-type calcium channel plays a dominant role in transmitter release evoked by inhibition of Na⁺,K⁺-ATPase, but other routes of calcium entry in addition to these channels can also support the release of neurotransmitter induced by ouabain.     

豚鼠小肠神经节丛的NADPH—黄递酶组织化学观察

目前已知,ＮＡＤＰＨ－－黄递酶组化法可选择性地显示－－氧化氮合成酶（ＮＯｓｙｎｔｈａｓｅ,ＮＯＳ）神经元。因此,我们以ＮＡＤＰＨ－黄递酶组化法,观察了豚鼠小肠肌间神经丛和粘膜下神经丛的神经网格以及ＮＯＳ神经元。结果表明,三段小肠肌间神经丛的神经网眼大小和形态有明显差异,与对应的粘膜下神经丛相比,差异更显著。在肌间神经丛中,ＮＡＤＰＨ－黄递酶阳性神经元胞体大小不等;其长突起伸入节间束,而短突起较多,并可见短突起彼此连接．构成节内偶见的局部神经元回路。从小肠上段到下段,ＮＯＳ神经元数量呈下降趋势。在粘膜下神经丛,我们也观察到少数ＮＯＳ神经元。     

New vascular system in reptiles: anatomy and postural hemodynamics of the vertebral venous plexus in snakes.

Using corrosion casting, we demonstrate and describe a new vascular system--the vertebral venous plexus--in eight snake species representing three families. The plexus consists of a network of spinal veins coursing within and around the vertebral column and was previously documented only in mammals. The spinal veins of snakes originate anteriorly from the posterior cerebral veins and form a lozenge-shaped plexus that extends to the tip of the tail. Numerous anastomoses connect the plexus with the caval and portal veins along the length of the vertebral column. We also reveal a posture-induced differential flow between the plexus and the jugular veins in two snake species with arboreal proclivities. When these snakes are horizontal, the jugulars are observed fluoroscopically to be the primary route for cephalic drainage and the plexus is inactive. However, head-up tilting induces partial jugular collapse and shunting of cephalic efflux into the plexus. This postural discrepancy is caused by structural differences in the two venous systems. The compliant jugular veins are incapable of sustaining the negative intraluminal pressures induced by upright posture. The plexus, however, with the structural support of the surrounding bone, remains patent and provides a low-pressure route for venous return. Interactions with the cerebrospinal fluid both allow and enhance the role of the plexus, driving perfusion and compensating for a posture-induced drop in arterial pressure. The vertebral venous plexus is thus an important and overlooked element in the maintenance of cerebral blood supply in climbing snakes and other upright animals.     

The developmental stage and cell type dependent phosphorylation of eNOS in murine enteric mucosa and myenteric plexus

In order to clarify the developmental regulation of the eNOS activity in intestine by phosphorylation, we examined the immunohistochemical localizations of the eNOS phosphorylation sites at Ser¹¹⁷⁷, Ser¹¹⁶ and at Thr⁴⁹⁵ in cells of the mouse enteric mucosa and myenteric plexus at E13.5, E14.5, E16.5, E18.5, E20.5 and P3. In addition, in cells of the E16.5 stage the protein levels of eNOS and the phosphorylation sites of eNOS at Ser¹¹⁷⁷, Ser¹¹⁶ and at Thr⁴⁹⁵ were investigated by immunoblot. From E14.5 to P3, phosphorylation residues of eNOS at Ser¹¹⁷⁷ and at Ser¹¹⁶ were detected with different staining intensities in the enteric mucosa epithelium. In ganglion cells of the myenteric plexus Ser¹¹⁶ was identified at E18.5 to P3. The absence of phosphorylated Thr⁴⁹⁵ in cells of intestine during all developmental stages, was confirmed by immunoblot at E16.5. The immunoblot levels of eNOS and eNOS phosphorylated at Ser¹¹⁷⁷ and at Ser¹¹⁶ were comparable with the immunohistochemical results of E16.5 mouse intestine. It was concluded that development of epithelial cells of the enteric mucosa may be modulated by phosphorylation of eNOS at Ser¹¹⁷⁷ and at Ser¹¹⁶. The phosphorylation of eNOS in cells of the myenteric plexus is modulated at Ser¹¹⁶. These data suggest that there is a developmental stage and cell type dependent phosphorylation of eNOS.     

超声定位与解剖定位对小儿臂丛神经阻滞麻醉效果的比较研究

目的:探讨超声定位对小儿臂丛神经阻滞麻醉的效果及优势。方法:选取我院收治的上肢手术患儿54例,随机分为两组。其中对照组在解剖定位下进行麻醉,实验组在超声定位下进行麻醉。比较两组麻醉完成时间、用药剂量、起效时间及不良反应等。结果:实验组麻醉完成时间及麻醉起效时间均较对照组短,用药剂量较对照组少,差异有统计学意义(P0.05);实验组VAS评分较对照组低,差异有统计学意义(P0.05);实验组血肿发生率低于对照组,差异具有统计学意义(P0.05);实验组Honer综合征、局麻药毒性反应以及气胸的发生率均低于对照组,但两组差异无统计学意义(P0.05)。结论:超声定位下行小儿臂丛神经阻滞麻醉能够明显改善麻醉效果,减少麻醉完成时间、麻醉药物用量及麻醉起效时间,降低麻醉相关不良反应的发生率,值得临床推广。     

Elbow Flexion Contractures in Childhood in Obstetric Brachial Plexus Lesions: A Longitudinal Study of 20 Neurosurgically Reconstructed Infants with 8-Year Follow-up

Objective

 Little knowledge exists on the development of elbow flexion contractures in children with obstetrical brachial plexus lesion (OBPL). This study aims to evaluate the prognostic significance of several neuromuscular parameters in infants with OBPL regarding the later development of elbow flexion contractures.

Methods

 Twenty infants with OBPL with insufficient signs of recovery in the first months of life who were neurosurgically reconstructed were included. At a mean age of 4.6 months, the following neuromuscular parameters were assessed: existence of flexion contractures, cross-sectional area (CSA) of upper arm muscles on MRI, Narakas classification, EMG results, and elbow muscle function using the Gilbert score. In childhood at follow-up at mean age of 7.7 years, we measured the amount of flexion contractures and the upper arm peak force (Newton). Statistical analysis is used to assess relations between these parameters.

Results

 Flexion contractures of greater than 10 degrees occurred in 55% of our patient group. The relation between the parameters in infancy and the flexion contractures in childhood is almost nonexistent. Only the Narakas classification was related to the development of flexion contractures in childhood (p = 0.006). Infant muscle CSA is related to childhood peak muscle force.

Conclusion

 The role of infancy upper arm muscle hypotrophy/hypertrophy, reinnervation, and early elbow muscle function in the development of childhood elbow contractures remains unclear. In this cohort prediction of childhood flexion, contractures were not possible using infancy neuromuscular parameters. We suggest that contractures might be an adaptive process to optimize residual muscle function.     

Degree of Contracture Related to Residual Muscle Shoulder Strength in Children with Obstetric Brachial Plexus Lesions

Background and Objectives

 Little is known about the relation between residual muscle strength and joint contracture formation in neuromuscular disorders. This study aimed to investigate the relation between residual muscle strength and shoulder joint contractures in children with sequelae of obstetric brachial plexus lesion (OBPL). In OBPL a shoulder joint contracture is a frequent finding. We hypothesize that residual internal and external rotator strength and their balance are related to the extent of shoulder joint contracture.

Methods

 Clinical assessment was performed in 34 children (mean 10.0 years) with unilateral OBPL and Narakas classes I–III. External and internal rotation strengths were measured with the shoulder in neutral position using a handheld dynamometer. Strength on the affected side was given as percentage of the normal side. Contracture was assessed by passive internal and external rotations in degrees (in 0° abduction). Mallet classification was used for active shoulder function.

Results

 External and internal rotation strengths on the affected side were approximately 50% of the normal side and on average both equally affected: 56% (SD 18%) respectively 51% (SD 27%); r = 0.600, p = 0.000. Residual strengths were not related to passive internal or external rotation (p > 0.200). Internal rotation strength (r =  − 0.425, p <0.05) was related to Narakas class. Mallet score was related to external and internal rotation strengths (r = 0.451 and r = 0.515, respectively; p < 0.01).

Conclusion

 The intuitive notion that imbalances in residual muscle strength influence contracture formation cannot be confirmed in this study. Our results are of interest for the understanding of contracture formation in OBPL.     

Remote Paraparesis due to a Traumatic Extradural Arachnoid Cyst Developing 2 Years after Brachial Plexus Root Avulsion Injury: Case Report and Review of the Literature

Traumatic extradural arachnoid cyst is a rare entity. However, late appearance of paraparesis due to formation of an extradural arachnoid cyst as a sequel of brachial plexus injury is extremely rare and the literature regarding this issue is scarce revealing only 11 cases. Herein, we report a patient with delayed progressive spastic paraparesis appearing after a multilevel brachial plexus root avulsion injury where imaging revealed formation of a large traumatic extradural arachnoid cyst at the cervicothoracic region. Furthermore, to propose that a high-energy trauma might simultaneously result in delayed formation of an extradural arachnoid cyst. However, preganglionic root avulsion injury with pseudomeningocele formation in association with extradural arachnoid cyst is not reported previously. A case of a 36-year-old man with spastic paraparesis developing 2 years after a multilevel brachial plexus root avulsion injury is presented. Root avulsion had immediately resulted in complete paralysis of the left upper limb that had not ameliorated. Imaging studies of the cervicothoracic region disclosed left-sided multilevel pseudomeningoceles and a large extradural arachnoid cyst extending from C5 to T2. After appropriate en bloc laminotomy, the cyst was excised and the causative dural tear was closed. Subsequently, three large defects of pseudomeningoceles were obliterated with artificial dural patch for the prevention of cord herniation. This was followed with laminoplasty of the corresponding levels after dural closure. The postoperative course was uneventful and paraparesis recovered steadily within 2 months. Paraparesis even years after brachial plexus injury should be regarded as a serious event that deserves extensive imaging survey for the possibility of the formation of an extradural arachnoid cyst. Careful review of the literature disclosed that the current case is the 12th case that an extradural arachnoid cyst has developed after brachial plexus injury and the first example that the pathogenic factor that might be implicated in occurrence of this rare association could be clarified with review of the MRI features. Actually, the presence of posttraumatic pseudomeningoceles in association with an arachnoid cyst in the current case is in favor of the belief that only preganglionic root injuries that are in close proximity to the spinal canal had been the cause dural tear with remote formation of extradural arachnoid cyst.     

Nerve Transfer in Delayed Obstetrical Palsy Repair

Objective

 When root avulsions are detected in children suffering from obstetrical brachial plexus palsy (OBPP), neurotization procedures of different nerve trunks are commonly applied in primary brachial plexus repair, to connect distally the nerves of the upper limbs using healthy nerve structures. This article aims to outline our experience of neurotization procedures in OBPP, which involves nerve transfers in the event of delayed repair, when a primary repair has not occurred or has failed. In addition, we propose the opportunity for late repair, focusing on extending the time limit for nerve surgery beyond that which is usually recommended. Although, according to different authors, the time limit is still unclear, it is generally estimated that nerve repair should take place within the first months of life. In fact, microsurgical repair of OBPP is the technique of choice for young children with the condition who would otherwise have an unfavorable outcome. However, in certain cases the recovery process is not clearly defined so not all the patients are direct candidates for primary nerve surgery.

Methods

 In the period spanning January 2005 through January 2011, among a group of 105 patients suffering from OBPP, ranging from 1 month to 7 years of age, the authors have identified a group of 32 partially recovered patients. All these patients underwent selective neurotization surgery, which was performed in a period ranging from 5 months to 6.6 years of age.

Results

 Late neurotization of muscular groups achieved considerable functional recovery in these patients, who presented with reduced motor function during early childhood. The said patients, with the exception of five, would initially have avoided surgery because they had not met the criteria for nerve surgery.

Conclusion

 We have concluded that the execution of late nerve surgical procedures can be effective in children affected by OBPP.     

三通道电刺激仪的研制及对臂丛神经损伤的临床疗效

目的:研制可用于臂丛神经损伤治疗的三通道电刺激仪,并且将之应用于临床臂丛神经损伤患者,观察该仪器治疗臂丛神经损伤的临床效果。方法:由主控模块、显示模块、键盘模块、三个通道的电刺激发生器模块以及电源模块组成系统,可以连续交替释放脉冲刺激,针对不同神经和肌肉,选择不同的刺激位点。将60例臂丛神经损伤术后的患者随机分成试验组(30例)和对照组(30例),试验组术后第三周使用三通道电刺激仪治疗,对照组不做处理,患者术后随访6-12月后,观察患者上肢肩部、肘部功能恢复情况。结果:试验组治疗后上臂丛、全臂丛、下臂丛的肩部、肘部功能均好于治疗前,差异明显,均有统计学意义(P0.05);试验组上臂丛、全臂丛、下臂丛的肩部、肘部治疗效果均显著优于对照组,差异有统计学意义(P0.05)。结论:三通道电刺激仪可以有效地促进臂丛神经损伤后上肢功能的康复,可以对三组神经和肌肉交替进行电刺激,使用方便,并且便于携带,患者较为满意。