The effects of hypothermia on renal function and haemodynamics in the rat

The effects of 1–2 h of hypothermia a t 28d?C and rewarming on renal function were investigated in anaesthetized rats, using conventional clearance methods and the micropuncture technique. Renal blood flow (RBF) decreased from 7.3 ± 0.51 mL min^-1 at 37.5d?C (control) to 4.0 ± 0.47 at 28d?C, with almost complete restoration to 6.9 ± 0.59 mL min^-1 after rewarming. Systemic blood pressure remained essentially unaltered. The RBF reduction seen during hypothermia was due to a 75% increase in vascular resistance, mainly attributable to constriction of the afferent arteriole and increased blood viscosity. This was accompanied by a decline in glomerular capillary pressure from 56.7 ± 0.6 to 46.4 ± 1.3 mmHg, overshooting to 59.0 ± 0.7 mmHg. The glomerular filtration rate (GFR) decreased from 1.1 ± 0.08 to 0.6 ± 0.04 mL min^-l, returning to 1.0 ± 0.07 after rewarming, a pattern also observed for single nephron GFR. This resulted from a decrease in net driving force for glomerular filtration, whereas the filtration coefficient was not affected. Both proximal and distal tubular fluid flow decreased, but fractional reabsorption remained unchanged. In contrast, urine flow increased from 1.8 ± 0.16 to 5.7 ± 1.08 μL min^-1, returning to 2.1 ± 0.18, the increase during hypothermia mainly resulting from a disproportionately reduced fluid reabsorption beyond the mid-distal tubule.     

Histopathological effects of anthrax lethal factor on rat liver

Abstract

Bacillus anthracis, the causative agent of anthrax, has become an increasingly important scientific topic due to its potential role in bioterrorism. The lethal toxin (LT) of B. anthracis consists of lethal factor (LF) and a protective antigen (PA). This study investigated whether only lethal factor was efficient as a hepatotoxin in the absence of the PA. To achieve this aim, LF (100?µg/kg body weight, dissolved in sterile distilled water) or distilled water vehicle were intraperitoneally injected once into adult rats. At 24?h post-injection, the hosts were euthanized and their livers removed and tissue samples examined under light and electron microscopes. As a result of LF application, hepatic injury – including cytoplasmic and nuclear damage in hepatocytes, sinusoidal dilatation, and hepatocellular lysis – became apparent. Further, light microscopic analyses of liver sections from the LF-injected rats revealed ballooning degeneration and cytoplasmic loss within hepatocytes, as well as peri-sinusoidal inflammation. Additionally, an increase in the numbers of Kupffer cells was evident. Common vascular injuries were also found in the liver samples; these injuries caused hypoxia and pathological changes. In addition, some cytoplasmic and nuclear changes were detected within the liver ultrastructure. The results of these studies allow one to suggest that LF could be an effective toxicant alone and that PA might act in situ to modify the effect of this agent (or the reverse situation wherein LF modifies effects of PA) such that lethality results.     

Effect of direct exposure to low-intensity laser radiation on morphology and function of the zona fasciculata of the albino rat adrenal cortex

Medico-Biological Department, Research Institute of Laser Surgery, Moscow. Department of Histology, Smolensk Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Kupriyanov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 109, No. 6, pp. 598–600, June, 1990.     

Temporal analysis of REM sleep after nest-building behavior in nulliparous albino rat

EEG recording was performed, during nest-building behavior (NBB), from the hippocampus and sensorimotor cortex of nulliparous albino rats with simultaneous recordings of EMGs of neck-muscle and eye movements. The duration of NBB varied with a period of 4–5 days. However, the relative durations of behavioral transitions in NBB, i.e., nest-building, grooming, and sleeping, were regular in both long lasting and early terminated NBB. REM sleep was identified, in every instance, immediately after NBB. The latency of REM sleep was significantly tied to the termination of NBB without regard to the druation of NBB. Differences in the duration of NBB, however, affected REM-propensity: the longer the NBB was, the shorter the latency of REM sleep tended to be. NBB might accelerate the induction of the physiological condition responsible for REM sleep generation.     

Lipofuscin in the cerebellar cortex of albino rats: An electron microscopic study

Summary The ultrastructure of autofluorescent, PAS-positive lipofuscin in Purkinje, granule, Golgi epithelial, basket and stellate, microglial and perivascular cells in the cerebellar cortex of senescent rats is described. The membrane-bounded pigment is composed of three elements: 1) electron-lucent homogeneous droplets, 2) a granular matrix and 3) intensely osmiophilic patches. The proportions of these three components vary between cell types and one can grossly differentiate a neuronal and a glial lipofuscin. The lipofuscin granules of stellate and perivscular cells are different from lipofuscin of other cerebellar neurons and glia. It can be concluded from these morphological observations that each cerebellar cell type has its distinct lipofuscin.Supported by the Deutsche Forschungsgemeinschaft La 184/5I would like to thank Mrs. v. Bronewski and Mr. H. Boffin for their technical assistance     

Efferent renal nerve stimulation inhibits the antihypertensive function of the rat renal medulla when studied in a cross-circulation model

The aim of this study was to investigate the effects of renal nerve stimulation on the humoral renal antihypertensive system. An isolated kidney (IK) was perfused at normal or high arterial pressures from a normotensive assay rat by means of a perfusion pump. Perfusion pressure (PP) to the IK was 90 mmHg for a control period of 30 min. In three of five experimental groups PP was then increased to 175 mmHg. In two of the groups the renal nerves were stimulated at 2 (P-175_2Hz) or 5 Hz (P-175_5Hz) for 60 min. The remaining group served as a control (P-175_c). In two groups IK pressure was maintained at 90 mmHg with 5Hz nerve stimulation (P-90_5Hz) or without nerve stimulation (P-90_c). MAP of the assay rat decreased by 22 and 27% (P < 0.001) in the P-175_c and P175_2Hz groups, respectively during the 60 min period of nerve stimulation, but remained stable in P-175_5Hz. Renal blood flow increased in the IK when PP was increased in P-175_c, but did not change significantly in P-175_2Hz or P-175_5Hz. Blood pressure remained constant in the assay rat when the IK was perfused at 90 mmHg. The renal excretory functions of the IK decreased in a frequency dependent manner by 2 and 5 Hz renal nerve stimulation compared with P-175_c. We conclude that 5 Hz renal nerve stimulation inhibits the pressure dependent release of humoral depressor substances from an IK perfused at 175 mmHg, whereas this is not seen when stimulating at 2 Hz. It is suggested that the release of antihypertensive substances from the renal medulla requires an increased renomedullary blood flow.     

激光多普勒流量计观察单侧输尿管梗阻大鼠双侧肾皮质微循环血流变化

目的:用激光多普勒流量计观察单侧输尿管梗阻大鼠双侧肾皮质微循环血流的变化,探讨梗阻侧肾间质纤维化的发病机制及健侧肾的代偿机制。方法:成年雌性SD大鼠,随机分为假手术组和模型组。假手术组仅将输尿管游离但不结扎离断,模型组行单侧输尿管结扎术。术后第7、14和21天随机选取并处死各组中的6只大鼠,观察双肾病理学改变,并检测双侧肾皮质微循环血流。结果:H-E染色显示假手术组双侧肾各时间点肾单位结构正常,间质无增宽;模型组大鼠梗阻侧肾术后7 d出现早期间质纤维化的病理改变,并随梗阻时间延长逐渐加重;健侧肾小球系膜细胞增生并随代偿时间延长逐渐增多。肾皮质微循环血流,与假手术组比较,模型组大鼠健侧肾皮质微循环血流显著增加,梗阻侧肾皮质微循环灌注量先增加后进行性降低。结论:血液流变学改变、梗阻侧肾皮质微循环血流灌注量进行性减少是肾间质纤维化的发病机制之一;而健侧肾皮质微循环血流灌注量增高,在一定程度上有利于健侧肾的功能代偿。     

Comparative studies on the pre-and postterminal blood vessels in the cerebellar cortex of rhesus monkey, cat, and rat

Summary In the rhesus monkey, cat and rat, pial arteries give off branches which run vertically through all three layers of the cerebellar cortex. The large cortical arteries are surrounded by a perivascular space in the molecular layer. Their wall consists of several layers of smooth-muscle cells and the luminal endothelium. As the arteries reach the deeper layers of the cerebellar cortex, the number of smooth-muscle cells is reduced. In the rat, sometimes no smooth-muscle cells are detectable in the preterminal arterial vessels. If these deep arteries branch off by dichotomy of terminal vessels there occurs a gradual or complete loss of myocytes in all three species. In the cat, where cortical arteries give off branches at rightangles, there is a sphincter-like accumulation of smooth-muscle cells at the opening to the smaller branch.The postterminal vessels and veins in all species exhibit the smae mural structure found in capillaries. The wall consists only of an endothelium and occasional pericytes embedded in the basal lamina. Even the large veins which run to the pial veins show this simple mural structure.Dedicated to Prof. Dr. Dr. A. Dabelow in honour of his 80th birthdaySupported by the Deutsche Forschungsgemeinschaft (La 184/5)     

Efferent renal sympathetic nerve stimulation in vivo. Effects on regional renal haemodynamics in the Wistar rat,studied by laser-Doppler technique

Intrarenal blood flow regulation probably affects long-term blood pressure homeostasis. We have previously shown that 5 Hz renal sympathetic stimulation inhibits a humoral renal depressor mechanism, otherwise activated when increasing perfusion pressure to an isolated kidney in a cross-circulation set-up. This inhibition was suggested to occur as a result of a reduction of renomedullary blood flow. Little is known about nervous blood flow regulation within the medulla. Therefore in this study, total renal (RBF), cortical (CBF) and papillary (PBF) blood flows were separately measured by ultrasonic and laser-Doppler techniques in Wistar rats during graded renal sympathetic stimulations. Periods of 15 min stimulation at 0.5, 2 and 5 Hz were performed in random order. RBF decreased at 0.5 Hz by 1%, at 2 Hz by 16% (P < 0.001) and at 5 Hz by 49% (P < 0.001). In a similar fashion (r = 0.73, P < 0.001), CBF decreased by 1%, 10% (P < 0.001) and 37% (P < 0.001), respectively. By contrast, PBF increased by 2% at 0.5 Hz and 4% at 2 Hz, while it decreased at 5 Hz, by 4% (P < 0.05, compared with 2 Hz). It seems therefore, that superficial renocortical and total renal blood flows are closely regulated by renal sympathetic nerves with increasing vasoconstriction at higher frequencies, while medullary blood flow, on the other hand, seems to be under strong local control, tending to offset neurogenic flow restrictions.     

Autoregulation of renal blood flow in the rat

Summary Renal blood flow was measured in rats anaesthetized with pentobarbital sodium by employing the PAH clearance method and the¹³³Xe washout technique. Both methods were in good agreement. In 17 rats a 25% decrement of blood pressure was attained through haemorrhage; RBF measured by PAH clearance declined by 3%, according to¹³³Xe washout by 2.7%. In further 21 rats an increase of blood pressure by an average of 265 was achieved by occlusion of the carotid arteries; RBF measured by PAH clearance declined by 3%, according to¹³³Xe washout by 1.1%. RBF was therefore almost perfectly autoregulated during both experimental manoeuvres; glomerular filtration rate (inulin clearance) was autoregulated in a similar manner. Water and sodium excretion changed in proportion to changes of blood pressure.with technical assistance of JANA HOLLYOVÁ     

The regulation of blood perfusion in the renal cortex and medulla by reactive oxygen species and nitric oxide in the anaesthetised rat

Aims: The regulation of blood flow through the renal medulla is important in determining blood pressure, and its dysregulation in pathophysiological states, such as oxidative stress, may contribute to the development of hypertension. This investigation examined the hypothesis that reactive oxygen species has both direct and indirect actions, via scavenging NO, to determine the degree of blood perfusion through the renal medulla. Methods: Groups of male Wistar rats received a renal interstitial infusion of either tempol, a superoxide dismutase (SOD) mimetic, or tempol plus catalase (tem + cat), or diethyldithio‐carbamic acid (DETC) a SOD inhibitor, or L‐NAME alone or L‐NAME followed by DETC. Results: Medullary blood perfusion (MBP) increased by 16 ± 1% (P < 0.05) following the renal infusion of tempol and by 35 ± 4%% (P < 0.05) when tem + cat was infused. Cortical blood perfusion (CBP) was unchanged during the administration of tempol and tem + cat. The renal interstitial infusion of DETC reduced CBP by 13 ± 2%, (P < 0.05) and MBP by 22 ± 3% (P < 0.05). Infusion of L‐NAME to block NOS did not change CBP but decreased MBP by 12 ± 4%, which was (P < 0.05) less than the reduction obtained with DETC. Administration of DETC in the presence of L‐NAME reduced CBP and MBP by 17 and 14%, respectively, the latter response being approximately half that obtained when only DETC was infused. Conclusions: These findings demonstrated that both reactive oxygen species and NO determined the level of MBP. The findings support the hypothesis that reactive oxygen species can act both indirectly, via scavenging of NO, and directly via H₂O₂ to modulate blood perfusion in the medulla.     

Culture of human renal cortex epithelial cells

Summary A procedure is described for the establishment and propagation of epithelial cell rich cultures derived from normal human kidney cortex (NHK-C cells). Cells are harvested from tissue fragments of donor human kidney by progressive enzymatic dissociation. NHK-C cultures are morphologically heterogeneous but exhibit, predominantly, the functional characteristics of cells of the kidney proximal tubule. Supported by grants from the American Heart Association (Indiana Affiliate) and the Polycystic Kidney Research Foundation.     

Effects of hyperthermic seizures on the developing primary visual cortex of the rat

Febrile seizures occurring during childhood have been shown to interfere with the development of cognitive functions. However, an alteration of the developing sensory systems might also result from febrile seizures. In order to test this hypothesis, seizures were induced by hyperthermia in Long Evans rats on postnatal day 10. Extracellular single neuron recordings were carried out from postnatal days 15 to 30 and at adulthood. The response of neurons in the primary visual cortex to drifting sinusoidal gratings was recorded in anaesthetized rats. As soon as postnatal day 15, the neurons of rats having experienced a hyperthermic seizure showed significantly lower optimal spatial frequencies (SF), broader directional and temporal bandwidths, as well as higher contrast thresholds than did neurons recorded in normal rats. At adulthood, significantly broader spatial bandwidths and lower optimal temporal frequencies (TF) were obtained from neurons of rats subjected to hyperthermia. These results suggest that febrile seizures during infancy could affect the development of spatio-temporal receptive field properties of neurons in primary visual cortex. Such alterations of a sensory system might contribute to the cognitive deficits associated with early-onset febrile seizures.     

Activity of enzymes of gluconeogenesis in the renal cortex of rats with acute hypoxia

Activity of enzymes of gluconeogenesis in the renal cortex was studied in rats after exposure to a reduced atmospheric pressure (200 mm Hg) for 3 h. Hypoxic stress was shown to lead to an increase in the activity of phosphoenolpyruvate carboxykinase and alanine aminotransferase but to have no significant effect on activity of fructose-1,6-diphosphatase, glucose-6-phosphatase, and aspartate-aminotransferase. The ratio between glucose-6-phosphate activity and hexokinase activity was increased under these conditions.Department of Biochemistry, Khabarovsk Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR A. N. Klimov.) Translated from Byulleten' Éksperimental'noi biologii i Meditsiny, Vol. 85, No. 4, pp. 415–416, April, 1978.     

大鼠肾小体发生发育的形态学变化

目的:探讨大鼠肾小体发生发育过程中的形态变化规律。方法:采用光镜、电镜技术并结合体视学测量方法,对不同发育阶段大鼠肾小体进行形态观察和体视学计量。结果:大鼠肾小体的发育经过了逗号小体、S小体、Ⅲ期和Ⅳ期肾小体4个阶段,从胚龄18d到生后40d肾小体的体积大约增大86倍,肾小体的数目大约增大7倍,生后7d之后基本稳定。结论:大鼠肾小体发生始于胚龄16d,肾小体的体积于生后40d达到成年水平,肾小体的数目在生后7d达到高峰。     

The effects of recruitment of renal functional reserve on renal cortical and medullary oxygenation in non-anesthetized sheep

Aim

Recruitment of renal functional reserve (RFR) with amino acid loading increases renal blood flow and glomerular filtration rate. However, its effects on renal cortical and medullary oxygenation have not been determined. Accordingly, we tested the effects of recruitment of RFR on renal cortical and medullary oxygenation in non-anesthetized sheep.

Methods

Under general anesthesia, we instrumented 10 sheep to enable subsequent continuous measurements of systemic and renal hemodynamics, renal oxygen delivery and consumption, and cortical and medullary tissue oxygen tension (PO₂). We then measured the effects of recruitment of RFR with an intravenous infusion of 500 ml of a clinically used amino acid solution (10% Synthamin® 17) in the non-anesthetized state.

Results

Compared with baseline, Synthamin® 17 infusion significantly increased renal oxygen delivery mean ± SD maximum increase: (from 0.79 ± 0.17 to 1.06 ± 0.16 ml/kg/min, p < 0.001), renal oxygen consumption (from 0.08 ± 0.01 to 0.15 ± 0.02 ml/kg/min, p < 0.001), and glomerular filtration rate (+45.2 ± 2.7%, p < 0.001). Renal cortical tissue PO₂ increased by a maximum of 26.4 ± 1.1% (p = 0.001) and medullary tissue PO₂ increased by a maximum of 23.9 ± 2.8% (p = 0. 001).

Conclusions

In non-anesthetized healthy sheep, recruitment of RFR improved renal cortical and medullary oxygenation. These observations might have implications for the use of recruitment of RFR for diagnostic and therapeutic purposes.     

大鼠IgA肾病模型肾脏变化分析

目的探讨IgA肾病(IgA nephropathy,IgAN)大鼠肾小体、肾小囊、肾小球和近端肾小管病理变化。方法将20只SD雌性大鼠随机分成2组,即对照组和IgAN组(n=10)。用免疫荧光、HE染色和体视学方法,测出2组动物肾小体、肾小囊和肾小球体密度、球囊体积比、肾小体数密度、肾小体和肾小球长径、近端肾小管管腔和管壁面积及其比值,比较其差异。结果IgA免疫荧光染色,IgAN组皮质部见较强绿色荧光。与对照组比,IgAN组肾小体体密度增大,肾小囊体密度增大,肾小球体密度减小,球囊比减小,肾小体数密度变化差异无显著性,肾小体长径增大,肾小球长径减小,近端肾小管管腔面积减小,管壁面积增大,腔壁比减小。结论 IgAN大鼠肾小体和肾小囊增大,肾小球减小,近曲小管细胞体积增大,管腔变小。     

The effects of high-frequency microstimulation of the cortex on interhemisphere synchronization in the rat motor cortex

Studies were carried out on long-term changes in the synchronization of neuronal activity in networks including callosal cells of the opposite hemispheres evoked by higher-frequency microstimulation in the motor cortex of anesthetized rats. The level of synchronization was assessed in terms of the amplitude and width of peaks located symmetrically on, cross-correlograms relative to the coordinate origin. Tetanization predominantly decreased synchronization in a group of initially background-active neurons, while there was a significant number of synchronously firing neurons in a group of cells which became activated. “Supernarrow” peaks appeared in interhemisphere interactions. There was a correlation between the type of modification of “narrow” (<20 msec) and “intermediate” (30–80 msec) peaks and changes in the efficiencies of mono- and polysynaptic connections. Translated from Rossiiskii Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 84, No. 7, pp. 614–623, July, 1998.     

人淋巴结窦内出现血液成分的组织病理学研究

目的：探讨人淋巴结窦内出现血液成分的组织病理学特点及其意义。方法：选择102例常规尸检病例的双侧颈部、腋窝、腹股沟、胸腔、腹腔8个部位的淋巴结共1322枚，石蜡切片，HE染色、光镜观察，分析淋巴结窦内出现红细胞时的组织结构改变，并对淋巴窦进行分类。结果：在100例因疾病死亡的患者的1322个淋巴结中，91例（占91％）患者的809个淋巴结（占61．20％）的淋巴窦内出现红细胞；而在2例非疾病原因死亡的尸检患者淋巴结的淋巴窦内则未见红细胞。根据淋巴结窦内红细胞出现后，组织结构变化的不同形态，将其分为5种不同的类型：血管开放淋巴窦、少血淋巴窦、噬血淋巴窦、富血淋巴窦、血管形成淋巴窦。结论：在疾病终致死亡状态下，淋巴窦出再现血液成分并不少见，淋巴结内淋巴循环与血液循环在淋巴窦内的交通，可使淋巴组织借助淋巴窦直接接受来自血液循环中的各种信息；并可能与恶性肿瘤出现淋巴结的跳跃性转移有关。