Calcium uptake and release modulated by counter-ion conductances in the sarcoplasmic reticulum of skeletal muscle

The sarcoplasmic reticulum (SR) plays the central role in regulating the free myoplasmic Ca²⁺ level for the contractile activation of skeletal muscle. The initial stages of the voltage-controlled Ca²⁺ release mechanism are known in molecular detail. However, there is still very little known about the later stages of Ca²⁺ uptake and total Ca²⁺ turnover in the contraction–relaxation cycle under normal physiological conditions or under conditions influenced by fatigue or disease. Ca²⁺ uptake and release are both accompanied by ‘counter-ion’ movements across the SR membrane which prevent or reduce the generation of SR membrane potentials and balance for electroneutrality in the SR lumen. The SR membrane is permeable for the cations K⁺, Na⁺, H⁺ and Mg²⁺ and the anion Cl^-. Using electron-probe X-ray microanalysis, it has been shown that during tetanic stimulation the Ca²⁺ release was mainly balanced by uptake of K⁺ and Mg²⁺, leaving a charge deficit that was assumed to be neutralized via H⁺ ion or organic counter-ion movement. The low time resolution of electron-probe X-ray microanalysis leaves the possibility of other transient concentration changes in the SR, e.g. for Cl^- ions. Possible physiological roles of the SR counter-ion conductances can be tested using skinned muscle fibre preparations with intact sarcoplasmic reticulum and removed or chemically permeabilized outer sarcolemma. In skinned fibres, the SR K⁺ conductance can be effectively reduced with SR K⁺ channel blockers such as 4-aminopyridine, tetraethylammonium and decamethonium. Interestingly, these blockers increase Ca²⁺ loading as well as Ca²⁺ release, whereas other less specific blockers, such as 1.10-bis-quanidino-n-decane, seem to reduce Ca²⁺ release, possibly also via blocking Ca²⁺ release channels. Thus, it seems very important also to test the effects of counter-currents carried by K⁺, Mg²⁺, H⁺ or Cl^- ions on intact and voltage-clamped single-fibre preparations.     

Expression of ICAM-1, VCAM-1 and ELAM-1 in angiofollicular lymph node hyperplasia (Castleman''s disease): evidence for dysplasia of follicular dendritic reticulum cells

The inducible adhesion molecules mediate important functions in the lymphoid tissues. We have investigated the expression of intercellular adhesion molecule 1 (ICAM-1), endothelial leucocyte adhesion molecule 1 (ELAM-1), vascular cell adhesion molecule 1 (VCAM-1), and platelet endothelial cell adhesion molecule (PECAM/CD31), using immunocytochemistry on cryostat sections of five lymph nodes from patients with Castleman's disease of the hyaline-vascular type. All five cases were characterized by marked hyperplasia of follicular dendritic reticulum cells, which were extensively present even in the mantle zone. Hyperplastic follicular dendritic reticulum cells showed marked expression of VCAM-1, and weak expression of ICAM-1. In two cases, several dysplastic giant cells with aberrant, polyploid nuclei showed aberrant expression of ELAM-1, an endothelium-restricted molecule. Dysplastic giant cells were positive with DRC-1 (an antibody to dendritic reticulum cells), VCAM-1 and occasionally ICAM-1, were negative for the endothelial cell markers factor VIII-related antigen and CD31 and were non-proliferating (Kl-67-). Cells positive for ICAM-1 or VCAM-1 were rare in the interfollicular areas. In all cases vascular hyperplasia was prominent, but endothelial cells were poorly activated in terms of expression of inducible adhesion molecules and of HLA-DR antigens. The possibility that dysplastic follicular dendritic reticulum cells have a pathogenetic role in Castleman's disease is discussed.     

Immunocytochemical study of human lymphoid tissues with monoclonal antibodies against S-100 protein subunits

Summary The present study concerns the immunocytochemical localization of S-100 protein and subunits in the cells of human lymphoreticular tissue and their related tumours. The subunit is mainly localized in dendritic cells, most likely the dendritic reticulum cells (DRCs) located within the germinal centers, while the subunit is mainly localized in the interdigitating reticulum cells (IRCs) in the paracortical area and in Histiocytosis X cells. No immunoreactivity for either subunit was found in the majority of normal lymphocytes, macrophages, malignant lymphoma cells, or xanthoma cells.The DRCs and IRCs are generally considered to show different distribution in the lymphoid tissues and demonstrate some difference in their immunocytochemical and enzyme-histochemical features. It is suggested that S-100 subunits can be used as useful markers for these two types of dendritic cells and investigation of these subunits may provide more information for the study of human lymphoreticular system.     

Damage of purkinje cell axons following chronic phenytoin administration: An animal model of distal axonopathy

Summary An animal model of central distal axonopathy following chronic administration of phenytoin is described. Male C57/BL6J mice received diphenylhydantoin (DPH) in the daily diet (liquid diet Stardit, supplemented with vitamins) over a period of 8 weeks. Control and experimental animals were pair-fed.Twelve mice of both groups were perfused via the left ventricle with glutaraldehyde. Representative samples of the cerebral cortex (area 3), cerebellum (vermis and deep cerebellar nuclei), thalamus, hypothalamus, and liver were embedded in araldite. Semithin sections and electron microscopy of the cerebellar vermis revealed marked dystrophic changes in the Purkinje cell axons. The presynaptic segments of Purkinje cell axons in the deep cerebellar nuclei showed massive enlargement and swelling due to accumulation of spherical particles and tubular structures in the axoplasm. These structures represent a proliferation of the smooth endoplasmic reticulum.Identical changes were found in hepatocytes of treated animals. Because phenytoin induces hepatic microsomal enzymes, we suggest that phenytoin-related Purkinje cell damage may be produced by an induction of Purkinje cell microsomes with proliferation of the smooth endoplasmic reticulum which causes a swelling and enlargement of presynaptic segments of Purkinje cell axons in deep cerebellar nuclei. Chronic phenytoin administration to mice is a new model of phenytoin-induced encephalopathy and of distal axonopathy of cerebellar neurons.Supported by the Deutsche ForschungsgemeinschaftPresented in Part at the Joint Meeting of the German and Scandinavian Neuropathologists, Turku, Finland, June 3–4, 1983     

Intracellular mechanism of quinidine action on muscle contraction

Summary The mechanism of quinidine action on rabbit cardiac and skeletal muscle was examined with functionally skinned muscle-fiber preparations. By using these preparations we could correlate measurements of muscle tension with the effect of quinidine on the Ca²⁺ activation of the contractile proteins and on the Ca²⁺ uptake and release from the sarcoplasmic reticulum (SR). Effect of quinidine on the contractile proteins. Quinidine concentrations above 0.5 mmol/l increased the maximal Ca²⁺-activated tension development 12% for papillary muscle and 5% for soleus (slow-twitch). Adductor magnus (fast-twitch) showed no significant change. Quinidine (0.1–1.0 mmol/l) also increased the submaximal Ca²⁺-activated tension development for the three muscle types (papillary muscle=soleus>adductor magnus) and shifted the [Ca²⁺]-tension curves to the left in a dose-dependent fashion. Effects of quinidine on the Ca ²⁺ uptake and release from the SR. Sarcoplasmic reticulum of skinned fibers was loaded with Ca²⁺ (uptake phase), then Ca²⁺ was released by 25 mmol/l caffeine (release phase) giving a tension transient. The area under the tension transient was used to estimate the amount of Ca²⁺ released. Quinidine (>0.5 mmol/l) decreased the Ca²⁺ uptake (soleus>adductor magnus>papillary muscle) and increased the Ca²⁺ release [papillary muscle=soleus adductor magnus (only at 1.5 mmol/l, the highest concentration tested)] from the SR of all three muscles in a dose-dependent manner. Quinidine at low concentration (0.1 and 0.5 mmol/l) increased the caffeine-induced tension transient of papillary muscle and higher quinidine concentrations (1.0 and 1.5 mmol/l) decreased the caffeine-induced tension transient of soleus and adductor magnus during both the uptake and release phases. The decreased Ca²⁺ uptake of papillary muscle in 1.5 mmol/l quinidine was antagonized by increasing the free Mg²⁺ from 0.032 to 0.32 mmol/l.In summary, quinidine has similar mechanisms of action in all three muscles: increased Ca²⁺ activation of the contractile proteins, decreased Ca²⁺ uptake and increased Ca²⁺ release from the SR in functionally skinned muscle fibers. We conclude that quinidine-induced decreases in Ca²⁺ uptake by the SR could be responsible for quinidine-induced myocardial depression and that quinidine-induced increases in Ca²⁺ activation of the contractile proteins and Ca²⁺ release from the SR could be responsible for the increases in skeletal muscle contraction caused by quinidine.     

中药单体调控自噬干预胚胎植入的研究进展

胚胎植入是生殖过程中最关键的步骤之一,植入失败的胚胎无法继续发育,是导致不孕的重要原因之一。胚胎植入的成功依赖于子宫内膜的高容受性和具有植入能力的胚胎。自噬是细胞质、细胞器和内含物被双膜囊泡吸收并运输到溶酶体进行降解和再循环的过程,是一种维持内环境稳态的方式。大量证据表明,自噬在胚胎植入的各个环节有着重要的作用。基于此探讨了自噬与子宫内膜容受性和胚胎植入能力的关系,并根据最新的研究进展,梳理了大黄素、梓醇、芍药苷、白藜芦醇、叶酸、玉米赤霉烯酮、姜黄素、汉黄芩素、槲皮素、白杨素、小檗碱、芹菜素、菲西汀、山柰酚在内的14种中药单体调控自噬干预胚胎植入的不同环节的5个机制,包括促进子宫内膜基质细胞蜕膜化、促进细胞凋亡、调节激素水平、协调炎症、促进排卵,希望对今后中药单体提高胚胎植入的成功率提供参考及思路。     

“肾虚络瘀，肾络癥瘕”病机观与肾间质纤维化中自噬不足的相关性

肾间质纤维化（RIF）是由多种病因导致慢性肾脏疾病的主要病理特征,结合中医“络病学说”“癥瘕理论”与现代医学肾脏病理特征,“肾虚络瘀,肾络癥瘕”是RIF的主要病机,正气亏虚,累及肾气,肾虚气化不利,痰热瘀毒等实邪阻滞肾络,相互胶结,形成癥瘕,积聚于肾络导致了RIF。自噬是细胞体内将受损或衰老的细胞器、变性的蛋白质等代谢产物进行降解与重吸收的过程,自噬参与了RIF发生的诸多环节,与RIF发生发展关系密切,将自噬与中医学结合研究发现,机体内生痰热瘀毒等实邪的代谢与自噬降解和重吸收功能相关,自噬在一定程度上是消除痰热瘀毒等实邪的方式,正气不足,累及肾气,肾虚气化不利,自噬功能不足,会引起痰热瘀毒等实邪累积,瘀阻肾络则易形成肾络癥瘕造成RIF,肾虚络瘀是自噬不足的基础,肾络癥瘕是自噬不足的微观病理表现,自噬不足与肾络癥瘕形成具有相同的病机演变,该文就RIF“肾虚络瘀,肾络癥瘕”病机,结合RIF-自噬病理机制,深入探讨“肾虚络瘀-自噬不足-肾络癥瘕”在RIF的相关性,全面诠释“肾虚络瘀,肾络癥瘕”病机的科学内涵,以期从中医理论阐述自噬在RIF中的作用研究奠定基础,为RIF的治疗及其机制研究提供新...     

枳实-白术调节PINK1/Parkin信号通路介导的线粒体自噬改善慢传输型便秘大鼠结肠动力障碍

目的：基于线粒体自噬及磷酸酶及张力蛋白同源物诱导的蛋白激酶1(PINK1)/帕金蛋白(Parkin)通路观察枳实、白术及其配伍对慢传输型便秘大鼠结肠动力障碍的改善作用,为临床精准用药提供理论参考。方法：将56只雄性SD大鼠按体质量随机分成正常组、模型组、自然恢复组、枳实组、白术组、枳实-白术组和莫沙必利组,每组各8只。除正常组外,采用洛哌丁胺连续14 d灌胃(3 mg·kg^-1·d^-1)构建慢传输型便秘大鼠模型。造模成功后,除模型组继续洛哌丁胺诱导外,正常组和自然恢复组采用0.9%生理盐水灌胃,枳实组(1.35 g·kg^-1·d^-1)、白术组(2.7 g·kg^-1·d^-1)、枳实-白术组(4.05 g·kg^-1·d^-1)和莫沙必利组(1.56 mg·kg^-1·d^-1)大鼠分别给予相应的药物灌胃,连续7 d。观察药物对大鼠粪便数量、粪便含水率及小肠推进率的影响;苏木素-伊...     

基于“正虚邪滞”理论探讨肺癌自噬机制及中药干预进展

自噬是一种细胞自我保护和自我更新机制,与肺癌的发生发展密切相关,有利自噬可以减缓肺癌进展,而不利自噬能够促进肺癌进展,故调节自噬水平在肺癌治疗中具有重要意义。“正虚邪滞”是王永炎院士“虚气留滞”理论的延伸,是指因肺脾肾气亏虚,引发津液代谢异常,导致痰瘀阻滞的病理过程,以肺脾肾气亏虚为本、痰瘀阻滞为标,是肺癌的关键病机。肺癌的自噬机制与“正虚邪滞”有着相互贯通之处,肺脾肾气亏虚是肺癌有利自噬减弱的关键因素,进而抑制了肿瘤细胞凋亡,并导致有害物质蓄积;痰瘀阻滞是肺癌不利自噬增强的直接因素,进而促进了正常细胞自噬性死亡,削弱了免疫细胞对肿瘤细胞的免疫抑制作用,导致肿瘤细胞增殖和迁移。正虚与邪滞相合,致使自噬状态向着不利的方向不断发展,最终导致肺癌持续进展。因此,中医干预肺癌自噬机制需以扶正抗邪为原则,补益正气以治其本,祛痰化瘀以治其标,增强有利自噬的同时抑制不利自噬,将自噬水平调节到最佳状态,从而抑制肿瘤细胞增殖和迁移,促进肺癌的缓解。通过分析现有文献可知,目前通过自噬途径治疗肺癌的中医药以中药单体为主,中医药干预肺癌自噬的作用主要集中在促进自噬激活层面,这可能是因为藉由肺脾肾气亏虚引发的有利自噬减弱是肺癌发展的根本原因。