Toad urinary bladder: intercellular spaces

Vasopressin causes dilation of the intercellular spaces of the mucosal epithelium in toad bladder, an effect previously thought to result from enhanced net transepithelial water transport. Under conditions of zero net fluid transport, vasopressin exerted the same effect in seven tissues, which indicates that the width of the intercellular spaces cannot be taken as a reliable index of net transepithelial fluid transport.     

Absence of significant cellular dilution during ADH-stimulated water reabsorption

Water reabsorption across many "tight" urinary epithelia is driven by large transepithelial osmotic gradients and is controlled by antidiuretic hormone (ADH). Numerous investigators have concluded that ADH-induced water reabsorption causes large apparent increases in cell volume with concomitant cytoplasmic dilution. A central question in renal physiology has been how cellular homeostasis is maintained in tight urinary epithelia during antidiuresis. Previous direct measurements of cell membrane permeability to water and the present direct measurements of cell volume in collecting tubules of rabbit kidney cortex by quantitative light microscopy show that cell volume does not change significantly during transcellular water flow. Fluid transported across the epithelium accumulated in lateral and basal intercellular spaces; the effect was an increase in cell height and tubule wall thickness accompanied by maintenance of nearly constant cell volume. The stability of cell volume is a consequence of the relatively high water permeability of the blood-facing cell membrane.     

Inhibition of vasopressin action by atrial natriuretic factor

Atrial natriuretic factor results in diuresis in animals and humans, perhaps because atrial natriuretic factor increases renal blood flow. The possibility that this diuresis is due to direct inhibition of renal tubular epithelial water transport was examined in rabbit collecting tubules perfused in vitro. Atriopeptin III inhibition of the hydraulic conductivity response to the hormone arginine vasopressin but not to either 3'5'-cyclic adenosine monophosphate or forskolin was found. These results suggest that atriopeptin III acts proximal to cyclic adenosine monophosphate formation to directly affect vasopressin-stimulated water transport in the mammalian nephron. They also suggest a potential role for inhibition by atrial natriuretic factor of the renal response to arginine vasopressin as a contributor to a diuretic state.     

Somatostatin: occurrence in urinary bladder epithelium and renal tubules of the toad, Bufo marinus

Immunohistochemical techniques were used to detect immunoreactive somatostatin-like material in toad urinary bladder epithelium and in kidney distal tubules and collecting ducts. This material has immunological and chromatographic properties identical to those of synthetic cyclic somatostatin. The occurrence of somatostatin-like material in antidiuretic hormone-sensitive portions of the renal urinary system suggests a local regulatory or paracrine role for somatostatin.     

食蚊鱼泌尿系统结构

食蚊鱼泌尿系统包括中肾、输尿管、膀胱。中肾分化程度较低,包括肾小体和肾小管,无皮质、髓质之分,有肾小体聚集现象。肾小管由颈段、第一近曲小管、第二近曲小管、间段、远曲小管及搜集管组成。第一近曲小管上皮中有嗜伊红油滴细胞。肾中散布有淋巴髓样组织、甲状腺滤泡,因此肾脏为多种生理功能的复合性器官。输尿管位于两肾叶腹侧,粘膜层为单层柱状或假复层柱状上皮,缺粘膜下层,无纵肌,外膜甚薄或缺如。左右输尿管在后端合并,移行一段后突出形成膀胱。膀胱内壁具绒毛,绒毛表面为移行上皮。     

New Concept of Competitive Inhibition of the Renal Tubular Excretion of Penicillin

It has been found that the excretion of penicillin by a renal tubular transport mechanism could be physiologically inhibited reversibly. The basis for this effect is thought to be one of substrate competition between penicillin, which is excreted by the tubules, and 4'-carboxyphenyl-methanesulfonanilide, which is essentially refractory to excretion by that transport mechanism.     

Genetic analysis of digestive physiology using fluorescent phospholipid reporters

Zebrafish are a valuable model for mammalian lipid metabolism; larvae process lipids similarly through the intestine and hepatobiliary system and respond to drugs that block cholesterol synthesis in humans. After ingestion of fluorescently quenched phospholipids, endogenous lipase activity and rapid transport of cleavage products results in intense gall bladder fluorescence. Genetic screening identifies zebrafish mutants, such as fat free, that show normal digestive organ morphology but severely reduced phospholipid and cholesterol processing. Thus, fluorescent lipids provide a sensitive readout of lipid metabolism and are a powerful tool for identifying genes that mediate vertebrate digestive physiology.     

中国胆毒鱼类的研究

在我国民间想念吞服鱼胆可治目疾，然而因吞服鱼胆面 引起的中毒，危害身体健康事件时有发生，自1964-1999年的35年中，据不完全统计吞服有毒鱼胆而中毒的人类达451人，其中死亡达83人，死亡率为18.04%，本文主要叙述鱼胆中毒的概况，胆汁有毒成分（鲤醇），动物实验，中毒症状及治疗，经动物实验及多年的调研共发现12种淡水鱼类的胆汁有毒，它们均是鲤科鱼类，从理论上阐明吞服任何鲤科鱼类的鱼胆均是危险的。     

中国胆毒鱼类的研究

在我国民间想念吞服鱼胆可治目疾，然而因吞服鱼胆面 引起的中毒，危害身体健康事件时有发生，自1964-1999年的35年中，据不完全统计吞服有毒鱼胆而中毒的人类达451人，其中死亡达83人，死亡率为18.04%，本文主要叙述鱼胆中毒的概况，胆汁有毒成分（鲤醇），动物实验，中毒症状及治疗，经动物实验及多年的调研共发现12种淡水鱼类的胆汁有毒，它们均是鲤科鱼类，从理论上阐明吞服任何鲤科鱼类的鱼胆均是危险的。     

新生儿Fc受体的研究进展

新生儿Fc受体(FcRn)是负责上皮细胞主动转运免疫球蛋白IgG的受体.IgG是初乳中含量最丰富的免疫球蛋白成分,哺乳动物新生儿的免疫力主要依赖于从母体获得IgG,而母源IgG向乳汁中的分泌以及被新生儿摄取均需要穿越上皮屏障,这一过程就是FcRn的胞转作用.本文对FcRn的特性、转运机制及其研究进展进行综述.     

氟致小鼠肾脏组织形态结构损伤的观察

为研究氟致非骨相组织的损伤作用,选用20只20日龄的昆明小鼠,随机分为4组,每组5只,分别饲喂含0 mg/L、50 mg/L1、00 mg/L和150 mg/L氟化钠的饮水120 d,并通过石蜡组织切片观察氟对肾脏的损伤作用。研究结果表明:50 mg/L氟中毒组小鼠肾脏肾小管排列结构无异常变化,肾小球细胞出现空泡样病变。100 mg/L氟中毒组小鼠肾脏肾小管排列结构没有明显的异常,肾小球内皮细胞和肾小管上皮细胞出现空泡样变,并出现微核现象和凋亡样细胞,且近曲小管上皮细胞有脱落现象。150 mg/L氟中毒组小鼠肾脏肾小管排列结构轻微紊乱,肾小球内皮细胞和肾小管上皮细胞发生变性、坏死,肾小管内脱落的上皮细胞增多。     

Partition of tissue functions in epithelia: localization of enzymes in "mitochondria-rich" cells of toad urinary bladder

The mucosal epithelium of the toad urinary bladder reabsorbs sodium, acidifies the urine, and is responsive to neurohypophyseal hormnones. Mucosal epithelial cells, consisting of two major morphologic cell types, "mitochondria-rich" and "granular," were removed from the bladder and separated by density gradient centrifugation. The mitochondria-rich cells contained three times as much carbonic anhydrase activity as the granular cells. Oxytocin caused a 235 percent increase in the adenosine 3',5'-monophosphate content of mitochondria-rich cells but had no effect on the granular cells. The evidence indicates that the mitochondria-rich cell, which accounts for only 15 percent of the mucosal cells, plays a major role in the mediation of sodium ion and hydrogen ion transport in the toad bladder and is a specific site of action of neurohypophyseal hormones.     

A renal countercurrent system in marine elasmobranch fish: a computer-assisted reconstruction

Computer-aided techniques were used to reconstruct the complex renal tubular system in the dorsal kidney region of a marine elasmobranch fish, the little skate (Raja erinacea), from a series of light micrographs of serial sections. It was established that five individual segments of one nephron, consisting of two loops and a distal tubule, are arranged in parallel within an elongated closed tissue sac. Capillaries, which form a network around these nephron segments, enter and exit this sac at the same end. This anatomical arrangement suggests that a complex renal countercurrent multiplier system may be important in fluid regulation in these fish.     

Autologous immune-complex pathogenesis of experimental allergic glomerulonephritis

A renal tubular epithelial antigen is deposited in association with gamma globulin and complement in glomeruli from rats with experimental allergic glomerulonephritis induced by immunization with renal tubular antigens. Apparently, in normal kidneys this antigen is concentrated in the distal segment of the proximal convoluted tubular epithelium, and the principal source of this antigen in the glomerular deposits is autologous. This form of glomerulonephritis provides an experimental prototype for what may be termed "autologous immunecomplex" diseases.     

犬胆囊疾病的诊断与治疗

犬的胆囊疾病临床相对少见,主要包括胆管炎、胆囊炎和胆石症。根据顽固性呕吐 和腹泻的临床症状、B超检查及血液化验可以确诊。B超检查时注意与肝肿瘤的鉴别诊断。治 疗方法以消炎、促进胆汁排出或摘除胆囊为主。     

Sediment-Water Chemical Exchange in the Coastal Zone Traced by in situ Radon-222 Flux Measurements

In situ radon-222 flux experiments conducted in benthic chambers in Cape Lookout Bight, a small marine basin on the North Carolina coast, reveal that enhanced chemical transport across the sediment-water interface during summer months is caused by abiogenic bubble tube structures. Transport rates for dissolved radon, methane, and ammonium more than three times greater than those predicted on the basis of molecular diffusion occur when open tubes are maintained by semi-diurnal low-tide bubbling.     

Endoplasmic reticulum in rat renal interstitial cells: molecular rearrangement after water deprivation

Cylindrical bodies in renal interstitial cells of dehydrated rats are confluent with membranes of endoplasmic reticulum. The cylinder walls, composed of helically arranged pentagonal tubules, may represent a molecular rearrangement of the membrane structure. The cylinders may represent a morphologic expression of altered ergastoplasmic function possibly related to the production of concentrated urine.     

Extracellular replication of Listeria monocytogenes in the murine gall bladder

The bacterium Listeria monocytogenes can cause a life-threatening systemic illness in humans. Despite decades of progress in animal models of listeriosis, much remains unknown about the processes of infection and colonization. Here, we report that L. monocytogenes can replicate in the murine gall bladder and provide evidence that its replication there is extracellular and intraluminal. In vivo bioluminescence imaging was employed to determine the location of the infection over time in live animals, revealing strong signals from the gall bladder over a period of several days, in diseased as well as asymptomatic animals. The data suggest that L. monocytogenes may be carried in the human gall bladder.     

DDT: disrupted osmoregulatory events in the intestine of the eel Anguilla rostrata adapted to seawater

The drinking of seawater and absorption of water along with sodium across the intestinal epithelium are well-known osmoregulatory events in marine teleosts. The insecticide DDT impairs fluid absorption in intestinal sacs from eels adapted to seawater. Furthermore, this functional impairment has an enzymatic basis; DDT also inhibits the (Na(+) and K(+)) activated, Mg(2+)-dependent adenosine triphosphatase in homogenates of the intestinal mucosa. Thus, the extreme sensitivity of teleosts to organochlorine pollutants may involve the disruption of osmoregulatory transport mechanisms.     

Fluid transport: concentration of the intercellular compartment

Intercellular spaces of Periplaneta rectal pads are visible at a magnification of x 100 and distend during fluid uptake. Samples (0.025 to 0.1 nanoliter) obtained by micropuncture from the spaces were consistently more concentrated than the fluid in the rectal lumen. This observation supports the hypothesis of "local" osmosis in epithelial fluid transport.