Blockade of the human cardiac K+ channel Kv1.5 by the antibiotic erythromycin

Erythromycin administration has been associated with a prolongation of cardiac repolarization in certain clinical settings. This could be due to blockade of voltage-dependent K⁺ channels in the human heart. For this reason we examined the effects of erythromycin on a rapidly activating delayed rectifier K⁺ channel (Kv1.5) cloned from human heart and stably expressed in human embryonic kidney cells. When examined using the whole-cell patch clamp technique, erythromycin (100 μM) blocked Kv1.5 current in a time-dependent manner but required prolonged exposure to do so. However, when we examined Kv1.5 current using inside-out macropatches, erythromycin applied to the cytoplasmic surface rapidly (within 1-2 min) inhibited Kv1.5 current with an IC₅₀ value of 2.6 x 10^-5M (1.7 - 3.9 x 10^-5M, 95% C.L.). The main effect of erythromycin was to accelerate the rate of Kv1.5 current decay thereby reducing the current at the end of a prolonged voltage-clamp pulse. Erythromycin also blocked Kv1.5 current in both a voltage- and frequency-dependent manner but had little effect on the activation kinetics, deactivation kinetics, or the steady-state inactivation properties of Kv1.5. These data suggest that erythromycin acts as a blocker of an activated state of the Kv1.5 channel and that it may access its binding site from the intracellular face of the channel. This study is the first to examine the effects of erythromycin on a cloned human cardiac K⁺ channel. It is concluded that erythromycin blocks Kv1.5 at clinically relevant concentrations. Blockade of voltage-dependent K⁺ channels in the heart could contribute to the alterations in cardiac repolarization that have been observed with erythromycin. Received: 22 November 1996 / Accepted: 26 February 1997     

红霉素逆转人胃癌细胞株多药耐药性的研究

目的：研究以红霉素逆转人胃癌SGC7901／ADM亚株所呈现的多药耐药性。方法：应用递增阿霉素剂量的方法，诱导建立人胃癌细胞耐药亚株。试以红霉素逆转该耐药亚株对阿霉素等抗癌药物的耐药性，以MTT法测定各药之．细胞毒作用，用LSAB法检测亲本(SGC7901)与耐药细胞亚株(SGC7901／ADM)之P-糖蛋白的表达水平。结果：体外诱导建立之人胃癌细胞耐药亚株SGC7901／ADM，对阿霉素的相对耐受度较亲本细胞SGC7901提高了9.l倍；前者同时对长春新碱、鬼臼乙叉甙呈交叉耐药性，而对丝裂霉素和顺铂则不显示交叉耐药性。红霉素浓度为273、545、1090μmol／L时．均可提高阿霉素、长春新碱、鬼臼乙叉甙对SGC7901／ADM耐药细胞亚株的细胞毒作用。免疫细胞化学研究显示，约86％的耐药亚株表达P-糖蛋白，而亲本细胞则均为阴性。结论：非毒性剂量的红霉素可以逆转人胃癌耐药细胞株的耐药性。为临床上胃癌常规化疗方案中加用红霉素提供了实验依据。     

有机氮源对红霉素发酵影响的具体分析

红色糖多孢菌的摇瓶培养基中使用不同有机氮源时红霉素的效价明显不同。通过对不同有机氮源所含营养成分的逐步回归分析,我们得到有机氮源中的苏氨酸为影响红霉素效价的主要因子。最后向对照培养基中添加苏氨酸,则使红霉素的效价比对照培养基提高了22.85%。     

红霉素硬化疗法在非感染性疾病中的应用现状

红霉素的化学刺激作用一直被视为药物不良反应 ,近年通过对这一副作用进行深入的实验研究和临床验证 ,成功地用于许多难治性疾病的硬化治疗 ,取得了较好的效果。现就红霉素的硬化治疗新用途的国内外现状加以介绍。     

小剂量红霉素联合孟鲁司特钠治疗儿童哮喘临床疗效

目的：研究小剂量红霉素联合孟鲁司特钠治疗儿童哮喘的临床疗效。方法：选取河南科技大学第一附属医院2020年1月至2022年6月诊治的90例哮喘患儿,采用随机对照方法分为观察组和对照组,各45例。对照组采用孟鲁司特钠治疗,观察组采用小剂量红霉素联合孟鲁司特钠治疗,比较两组患儿疗效、并发症、肺功能、儿童哮喘控制测试(C–ACT)评分、血清炎症因子及T淋巴细胞的差异。结果：观察组患儿治疗总有效率高于对照组,差异具有统计学意义(P <0.05);观察组患儿消化道症状、肝肾功能损伤、嗜睡及心率失常发生率高于对照组,但差异无统计学意义(P> 0.05);观察组患儿治疗后用力肺活量(FVC)、第1秒用力呼气量(FEV1)、呼气流量峰值(PEF)及C–ACT评分均高于对照组,差异具有统计学意义(P <0.05);观察组患儿治疗后血清白三烯D4(LTD4)及肿瘤坏死因子–α(TNF–α)、CD3⁺、CD4⁺及CD8⁺均低于对照组,差异具有统计学意义(P <0.05)。结论：小剂量红霉素联合孟鲁司特钠可改善哮喘患儿肺功...     

新生儿难治性先天性乳糜胸的临床分析

目的探讨难治性先天性乳糜胸(CC)新生儿的临床特点、治疗方法。 方法选择2015年6月至2019年12月,在首都儿科研究所附属儿童医院住院治疗的11例难治性CC新生儿为研究对象,回顾性分析其临床表现、辅助检查结果、治疗、转归和随访情况。本研究遵循的程序符合2013年新修订的《世界医学协会赫尔辛基宣言》,并与患儿监护人签署临床研究知情同意书。 结果①一般临床资料：11例难治性CC患儿的起病日龄<28 d,入院日龄为1~103 d。其中男性患儿为6例,女性为5例;足月儿为8例,早产儿为3例,出生胎龄为31~40周;接受产前诊断为4例,合并胎儿水肿为3例。②临床表现：生后10 min内起病为7例,11例患儿均表现为呼吸急促,患侧肺部呼吸音减弱,胸部X射线摄片、胸部CT或胸部超声检查结果均提示胸腔积液,其中双侧胸腔积液为7例,单侧胸腔积液(左侧)为4例,胸腔积液乳糜试验均呈阳性。③治疗方法：入院后,对11例患儿均进行保守治疗(饮食调节、呼吸支持、胸腔闭式引流、奥曲肽微量泵持续注射治疗、抗感染治疗等) 2~4周,失败后,对10例采用化学胸膜固定术(胸腔内注射红霉素),其中7例患儿联合奥曲肽微量泵持续注射治疗,单侧胸腔注射次数为1~7次,未同时联合奥曲肽微量泵持续注射治疗者,胸腔内单侧注射红霉素次数为3~7次。胸腔内注射红霉素过程中,4例患儿出现心率加快、烦躁,1例出现明显血糖浓度升高(18.8 mmol/L)。2例患儿行胸腔镜下探查术和乳糜瘘修补术。④转归：11例难治性CC经治疗后,均吸收好转,住院天数为40~73 d,其中1例自动出院后死亡,1例因怀疑气管食管瘘家长放弃治疗后失访。其余9例患儿出院后均无复发。 结论难治性CC多见于足月儿,对其采取早期饮食调节、静脉营养、胸腔穿刺闭式引流和奥曲肽静脉输注保守治疗2~4周无效的患儿,可联合化学胸膜固定术(胸腔内注射红霉素)治疗。对于上述治疗>4周无效者,可采用胸腔镜下探查术,明确渗漏点后,予以淋巴管瘘修补术,以提高对难治性CC的治愈率。     

应用威布尔分布函数研究红霉素微囊的溶出度

本文测定了红霉素微囊在人工肠液中的溶出度，并用威布尔分布函数求出了溶出百分率与时间的关系。     

Effect of erythromycin on the oro-caecal transit time in man

Summary Erythromycins often cause gastrointestinal side-effects due to an increase in motility or to change in the intestinal bacterial flora. In order to evaluate the effect of erythromycin on gastrointestinal motility, 11 healthy volunteers were given placebo, erythromycin stearate (ES) 1000 mg or a therapeutically equivalent single dose of erythromycin acistrate (EA, 2-acetyl erythromycin stearate) 800 mg in a double-blind trial. The orocaecal transit time was measured using the hydrogen breath test with lactulose as the substrate. The transit time was estimated from the H₂-peak (ppm) in end-expiratory breath by two methods, t₁ representing the front and t₂ the bulk of lactulose reaching the colon.t₁ was 51 min in the placebo group, 38 min in the EA and 31 min in the ES group (p < 0.05, ES vs placebo). t₂ was 74 min, 64 min, and 46 min, respectively (p < 0.05, ES vs placebo). The difference between EA and ES was also significant. Six subjects in the ES group but none in the EA group recorded adverse gastrointestinal effects attributable to medication.It was concluded that erythromycin shortens the orocaecal transit time in man and that EA affects the transit time slightly less than ES.     

Ca2+ dependence of motilide-induced contractions in rabbit duodenal muscle strips in vitro

Summary Recent studies suggested that certain erythromycin A (EM-A) derivatives are motilin receptor agonists. As proposed by Itoh they may be called motilides. We have investigated the Ca²⁺-dependence of contractions induced by two potent motilides, ME-34 [de(N-methyl) 8,9-anhydroeryhtromycin A 6,9-hemiacetal] and EM-523 [de(N-methyl)-N-ethyl-8,9-anhydro-erythromycin A 6,9-hemiacetal], in duodenal tissues and compared the results with those previously obtained with motilin.Isometric and isotonic contractile responses of isolated longitudinal muscle sheets from the rabbit duodenum were tested under normal, Ca²⁺-free and depolarizing conditions. Prior to stimulation with motilides, the maximal response to acetylcholine was recorded and all responses were always expressed as a percentage of this response. Both motilides induced contractions in normally polarized tissue, with an EC₅₀ of 26 ± 5 nM for ME-34 (n = 7), and 27 ± 5 nM for EM-5231 (n = 16) and maximal responses of respectively 88 ± 4% and 80 ± 3%. Like motilin, both compounds induced an extra-contraction in depolarized tissues. The EM-523 response in 140 mM K⁺under isotonic conditions was 84 ± 3% (n = 5) at 10^–5 M, with an EC₅₀ that was shifted to 65 ± 18 nM. Similar figures were obtained for ME-34. When Ca²⁺ was added to Ca²⁺-depleted strips, half-maximal Ca²⁺ values (in mM) were 1.10 ± 0.11 (n = 9) for EM-523 and 1.13 ± 0.12 (n = 3) for ME-34, as compared with 1.12 ± 0.13 (n = 7) for motilin and 2.8 ± 1.1 (n = 9) for K⁺. Both ME-34 and EM-523 also induced a transient contraction in Ca⁺-free solutions under isometric conditions. The response to EM-523 (5 × 10^–6 M) was 49 ± 15% (n = 4) after 3 min. A maximal EM-523 -stimulation reduced a subsequent ACh response by 78 ± 7%, whereas EM-523 and ME-34 could not induce a contraction after ACh.We conclude that motilides depend upon external Ca²⁺ to a similar extent to motilin. Like motilin, they are also able to mobilize intracellular Ca Z + stores. Our results support the hypothesis that motilides act on motilin receptors. Send offprint requests to T. L. Peeters at the above address     

红霉素、阿奇霉素联合短程治疗小儿支原体肺炎临床研究

目的探讨红霉素、阿奇霉素联合短程和红霉素、阿奇霉素常规治疗小儿肺炎支原体肺炎,是否具有相同的疗效,并比较两种方案的安全性。方法180例肺炎支原体肺炎患儿随机分为两组,观察组80例,静脉滴注红霉素30mg·kg-1·d-1后同时口服阿奇霉素10mg·kg-1·d-,连续3天。对照组100例静脉滴注红霉素30mg·kg-1·d-1,连续7天后改为口服阿奇霉素10mg·kg-1·d-,连续3天。详细记录症状、体征、X线等及复查肝功能。结果观察组与对照组在治疗后3天,两组均能较好地控制发热、咳嗽等症状,治疗2周后X线检查病灶均基本吸收,疗效无显著差异(P>0.05)。结论对小儿肺炎支原体肺炎,红霉素、阿奇霉素联合短程与红霉素、阿奇霉素常规治疗疗效无差异,安全性相同。但前者既可缩短患者住院时间,减少用药频率,同时可减轻患儿家庭经济负担。