Effect of the method of blood extraction on plasma levels of renin in the Wistar rat

To investigate the influence of blood extraction conditions on the renin-angiotensin system in rats, plasma renin activity (PRA) and plasma renin concentration (PRC) were measured in blood samples obtained by different methods. PRA and PRC in samples obtained by chronic catheterization, cardiac puncture without anesthesia, and decapitation immediately following light ether anesthesia were not significantly different from those obtained by simple decapitation (control group). In contrast, PRA and PRC in samples obtained by cardiac puncture and cavernous sinus puncture after light ether anesthesia were significantly (p less than 0.01) higher than those obtained in the control group. There was a significant direct correlationship between PRA and PRC in all samples studied (r = 0.87, p less than 0.001). The present results suggest that light ether anesthesia increases renin levels, except when blood samples are taken by decapitation, and that chronic catheterization and cardiac puncture are the choice blood extraction methods to evaluate the renin-angiotensin system in rats.     

The comparative influence of anesthetics on the in vitro proton NMR relaxation times in rat liver

To determine the effect of anesthetics on liver relaxation times in rat, two experiments were performed. In the first experiment, normal and protein-depleted rats underwent total hepatectomy under ether anesthesia or following decapitation. In the second experiment, livers were excised from normal rats under ketamine or pentobarbital anesthesia, or following decapitation. Hepatic T1 and T2 were measured for all animals using a RADX 10 MHz spin analyzer. Ketamine produced T1 values significantly different from decapitation. Ketamine, pentobarbital, and ether in normal animals all produced T2 values significantly different from decapitation. It is apparent that anesthetization of rats prior to in vitro measurement of hepatic relaxation times is not equivalent to decapitation; nor are the anesthetics examined equivalent to one another.     

Prolactin response to stress in neonatally estrogenized male rats

Male Wistar rats were injected either 500 micrograms of estradiol benzoate or olive oil on their first day of life. Blood samples were obtained from the adult by decapitation, by decapitation after 15 min of restraint, by decapitation 10 min after a 5 min period of ether exposure or by jugular venipuncture after 60 s of ether exposure. Prolactin (PRL) plasma levels were measured by RIA. The PRL levels in samples obtained by decapitation were similar to control and estrogenized groups. A similar response to restraint was also found in both groups. Sixty s of exposure to ether stress stimulates PRL secretion only in the estrogenized males, this effect being blocked by treatment with Normifensine (5 mg/kg two hours prior to blood sampling). These results suggested that estrogenized male rats show greater sensitivity to acute ether stress than the controls, and that changes in the dopaminergic system could be involved in this response.     

Testosterone and zinc supplementation in castrated rats: Effects on plasma leptin levels and relation with LH, FSH and testosterone

The present study aims to examine how zinc and testosterone supplementation, in combination and separately, affect plasma LH, FSH and leptin levels in castrated rats. Eighty experimental animals used in the study were allocated to 8 groups, each containing an equal number of rats. Group 1, control group; Group 2, castration group; Group 3, testosterone group (5 mg/kg/day); Group 4, zinc-supplemented group (3 mg/kg/day); Group 5, testosterone and zinc-supplemented group; Group 6, zinc-supplemented castration group; Group 7, testosterone and castration group; and Group 8, zinc-supplemented, testosterone and castration group. Plasma zinc, leptin, LH, FSH and free and total testosterone levels were determined in the blood samples collected from the animals by decapitation. Group 2 had the highest leptin levels and together with group 6, it also showed the highest LH and FSH levels (p<0.01). The lowest leptin levels were observed in groups 3 and 7 (p<0.01). Leptin levels in groups 4 and 6 were higher than those in groups 1, 5 and 8 (p<0.01). LH levels in group 4 were lower than those in groups 2 and 6 and higher than those in all other groups (p<0.01). Free and total testosterone levels in groups 7 and 8 were lower than those in groups 3 and 5, but higher than those in all other groups (p<0.01). Plasma LH levels may be more effective than testosterone on plasma leptin and zinc may be an important mediator of the effect LH has on leptin.     

丙泊酚与咪哒唑仑复合氯胺酮用于小儿心导管术麻醉效果研究

目的:探讨丙泊酚与咪哒唑仑复合氯胺酮用于小儿心导管术麻醉的优缺点与安全性。方法:将2008年7月~2012年7月入住我院的100例行心导管术的先心病患儿按照抽签法随机地均分为A、B组,A组采用6 mg/(kg·h)丙泊酚+3 mg/(kg·h)氯胺酮维持,B组采用0.15 mg/(kg·h)咪达唑仑+3 mg/(kg·h)氯胺酮维持,比较两组麻醉效果、HR、SPO2、MAP、体动次数、停药唤醒时间及不良反应发生率。结果:对照组麻醉优良率为80.00%,小于观察组(100.00%)(P0.05);两组术前MAP、HR差异无统计学意义(P0.05),但股动脉穿刺时二者差异具有统计学意义(P0.05),两组术中SPO2差异无统计学意义(P0.05),两组体动次数、停药唤醒时间相比,具有统计学差异(P0.05,P0.01);对照组不良反应发生率为24.00%,明显大于观察组(10.00%),两组相比,差异具有显著的统计学意义(P0.01)。结论:咪哒唑仑复合氯胺酮用于小儿心导管术麻醉效果显著,安全性高,值得在临床上加以推广并应用。     

Effects of surgery and epidural or general anaesthesia on testosterone, 17-hydroxyprogesterone and cortisol plasma levels in prepubertal boys

Testosterone (T), 17-hydroxyprogesterone (17P) and cortisol (F) plasma levels have been measured in two groups of prepubertal boys before and during surgery under general anaesthesia (Group 1) and epidural anaesthesia (Group 2) respectively. The mean plasma levels of T, 17P and F increased significantly (P less than 0.05; P less than 0.001; P less than 0.005, respectively) during surgery in Group 1; in Group 2 the plasma levels of T and F did not show any significant variation, whereas 17P significantly increased (P less than 0.05). However the mean level reached by 17P in Group 2 was significantly lower (P less than 0.005) than that observed in Group 1. No significant variation of LH and FSH plasma levels was observed in either group. Our report suggests that the modifications of T and 17P plasma levels observed during surgery under general anaesthesia (GA) are probably due to the stress induced adrenal response. This response can be inhibited or reduced by epidural anaesthesia (EA).     

Hormonal effects of lead acetate in the male rat: mechanism of action

Environmental exposure to toxic levels of lead occurs in a number of industries with potential adverse effects on the reproductive capacity of exposed men. Using a rat model, we previously reported that dietary exposure to lead resulted in suppressed spermatogenesis and testosterone levels without significant changes in luteinizing hormone (LH). In this study, to identify more specifically the site of lead's toxic actions on the hypothalamic-pituitary-testicular axis, the response of lead-treated male rats as compared to control animals to naloxone, gonadotropin-releasing hormone (GnRH), and LH stimulation was studied. Three groups of 52-day-old Wistar rats were allowed access to either deionized distilled water containing no lead acetate or a 0.3% lead acetate solution for 30 days. In each study group, 10 control and 10 lead-treated animals were anesthetized prior to cardiac puncture and collection of serum for the measurement of lead level and baseline LH (Groups I and II) or testosterone levels (Group III). In Group I, 20 min after an i.p. injection of naloxone (1.5 mg/kg/BW), the animals were killed by decapitation, and serum was collected for LH measurement. Thirty minutes after an i.p. injection of GnRH (100 ng/100 gm BW), Group II animals were killed by decapitation, and serum was collected for LH. Sixty minutes after an injection of LH (100 mg/100 mg BW), serum was collected from Group III animals for testosterone measurement. All control animals and lead-treated animals consumed similar volumes of water. Control animals had undetectable levels of lead in their blood. Lead-treated animals had mean blood lead values of 30 micrograms/dl +/- 5 micrograms/dl.(ABSTRACT TRUNCATED AT 250 WORDS)     

Endocrine stress response in rats subjected to singular orbital puncture while under diethyl-ether anaesthesia.

In an attempt to assess possible discomfort in rats subjected to orbital puncture while under diethyl-ether anaesthesia, their endocrine stress response was determined. Concentrations of corticosterone, adrenaline and noradrenaline were measured in plasma obtained via a jugular catheter from rats subjected to diethyl-ether anaesthesia with or without orbital puncture. No statistically significant differences were found between the punctured and non-punctured rats as to peak levels of plasma corticosterone and adrenaline as well as for the times required by the increased concentrations to return to baseline values. The rate by which the plasma noradrenaline level returned to baseline values was somewhat decreased by orbital puncture. Diethyl-ether anaesthesia alone produced a marked endocrine response when compared with handling and novelty stress associated with the induction of anaesthesia. It is concluded that diethyl-ether anaesthesia causes pronounced increases in the plasma levels of the selected stress hormones and that orbital puncture does not amplify this response. It is suggested that diethyl-ether anaesthesia masks any effects of orbital puncture.     

In vivo studies of carnitine and fatty acid metabolism: Problems with use of anesthetics

The use of ether anesthesia as a technique for obtaining liver tissue and plasma from living rats was compared to decapitation followed by in situ sample freezing. Parameters associated with fatty acid metabolism were examined to demonstrate differences in the two methodologies. Use of ether in fasted rats was associated with lower plasma free fatty acids and acetoacetate concentrations, as well as decreased hepatic total carnitine, carnitine, and acid-soluble acylcarnitine content when compared to decapitated animals. No qualitative differences between the ether and decapitated groups were noted, and the quantitative differences observed were consistent with effects induced by the anesthetic. Thus, with respect to in vivo studies of fatty acid metabolism use of anesthetic agents may induce significant changes without providing advantages over decapitation and in situ freezing.     

Ketamine does not affect intestinal microcirculation in pentobarbital-anaesthetized rats during experimental endotoxaemia

The objective of the study was to evaluate the effects of ketamine on intestinal microcirculation in pentobarbital-anaesthetized rats during experimental endotoxaemia. A prospective, randomized, controlled study was carried out using 32 male Lewis rats. The animals were divided into four groups (n = 8 each). All animals were initially anaesthetized with 60 mg/kg pentobarbital (i.p.). Group 1 served as a control (18.5 mg/kg/h pentobarbital i.v.). Groups 2 and 4 received an endotoxin intravenous infusion of 15 mg/kg lipopolysaccharide (LPS) from Escherichia coli. Groups 3 and 4 also received 10 mg/kg/h ketamine (i.v.). After 2 h of observation, the animals were examined for intestinal functional capillary density (FCD) and leukocyte adherence to the venular endothelium by means of intravital fluorescence microscopy (IVM). Subsequent to this examination, blood samples were collected to determine release of the cytokines tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-6 and IL-10. Endotoxaemia tended to decrease intestinal FCD (mucosa: -10.1%, muscularis longitudinalis: -2%, muscularis circularis: -9.8%) and significantly increase leukocyte adherence within submucosal venules (collecting venules: +133%, postcapillary venules: +207%; P<0.05). TNF-alpha, IL-1beta, IL-6 and IL-10 levels were significantly elevated following endotoxin challenge. The addition of ketamine to pentobarbital anaesthesia did not significantly affect FCD, leukocyte behaviour or cytokine levels. In conclusion, intravenous pentobarbital anaesthesia with the additional administration of ketamine did not cause alterations within the microcirculation or changes in cytokine release during endotoxaemia. In rats, the combination of pentobarbital and ketamine is suitable for use during the study of intestinal microcirculation in experimental endotoxaemia.     

Magnesium, calcium and zinc levels in plasma and erythrocytes of spontaneously hypertensive rats

Magnesium, calcium and zinc determinations were performed by flame absorption spectrophotometry and induced coupled plasma on the red blood cells (RBC) and plasma (P) of spontaneously hypertensive (SHR) and control (WKR) male rats, aged of 45 to 158 days. The blood sampling was done by cardiac puncture after ether anaesthesia. SHR rats have lower RBC and P Mg values and higher RBC Zinc values than WKR. These differences are very significant (P less than 0.002 to P less than 0.0001) among the animals aged of 96 days or more. When compared to the data of the literature, these results confirm the existence of associations between hypertension, low blood Mg and high RBC Zn values but reveal only minor changes in RBC Ca concentrations.     

Effects of sampling on blood parameters in the rainbow trout, Salmo gairdneri Richardson

The effects of sampling and short-term storage of blood samples on the blood parameters of rainbow trout were evaluated by comparing values obtained from resting fish sampled via cannulae and from fish sampled by cardiac puncture. Sampling stress causes an increase in haematocrit value and a decrease in mean cellular haemoglobin concentration, indicating red cell swelling. These changes are aggravated by consecutive storage of samples. Also, blood ionic balance is affected. The K⁺ concentration of plasma increases and plasma Cl⁻ concentration decreases owing to sampling. During storage the plasma K⁺ concentration decreases far below resting levels in samples taken by cardiac puncture, whereas plasma Cl⁻ level returns to pre-stress levels. Owing to the sampling- and storage-induced changes in blood parameters, care must be taken to ensure that similar sampling procedure is employed throughout to allow reliable comparisons between groups to be made.     

Impact of general injection anaesthesia and analgesia on post-castration behaviour and teat order of piglets

Injection anaesthesia with a combination of ketamine and azaperone (K/A) is discussed as a painless alternative to commonly used non-anaesthetized castration. To protect anaesthetized piglets from being crushed, they have to be separated from the sow for 3 h following castration. The aim of this study was to test if this separation and the different treatments would affect short-term behaviour after castration (3 to 6 h after castration) as well as weight gain. Piglets were 5 to 7 days old. Treatment Group 1 received a combination of anaesthesia and analgesia (n = 29, ketamine: 25 mg/kg BW; azaperone: 2 mg/kg BW; meloxicam: 0.4 mg/kg BW), Group 2 received only analgesia (n = 24) and Group 3 received no medication (n = 29). Behaviour and suckling order were compared for a 3 h period the day before castration and after castration. A significantly higher number of teats used by anaesthetized piglets (P = 0.004) suggests a decrease in suckling order stability. There were significant treatment effects between all three groups in the time spent at the sow's teat, with an increase in Group 2 (+69%), decrease in Group 1 (−28%), whereas the control Group 3 (+2%) almost remained unchanged. The anaesthetized piglets showed an increase in the time spent active away from the sow after castration of almost 200% (Groups 2 and 3: ∼50%, P < 0.001). However, no significant treatment effect was seen for weight gain. The results suggest that analgesia has an effect on behaviour, perhaps due to less post-castration pain. This advantage is not apparent for animals receiving additional anaesthesia, probably because of impaired coordination. Although the behavioural changes did not affect weight gain significantly, a decrease in suckling order stability indicates a certain degree of stress due to fighting over teat positions as a consequence of separation. Thus, post-castration behaviour must be taken into account when evaluating alternative castration methods.     

Quantification of bioactive acylethanolamides in rat plasma by electrospray mass spectrometry

We developed a high-performance liquid chromatography/mass spectrometry (HPLC/MS) method for the identification and quantification of anandamide, an endogenous cannabinoid substance, and other fatty acid ethanolamides (AEs) in biological samples. Using a mobile-phase system of methanol/water and gradient elution, we achieved satisfactory resolution of all major AEs, including anandamide, palmitylethanolamide (PEA), and oleylethanolamide (OEA). Electrospray-generated quasi-molecular species were used as diagnostic ions and detected by selected ion monitoring (SIM). Synthetic deuterium-labeled AEs were used as internal standards, and quantification was carried out by isotope dilution. A linear correlation (r2 = 0.99) was observed in the calibration curves for standard AEs over the range 0-0.5 nmol. Detection limits between 0.1 and 0.3 pmol per sample and quantification limits between 0.5 and 1.2 pmol per sample were obtained. The method was applied to the quantification of anandamide, PEA, and OEA in plasma prepared from rat blood collected either by cardiac puncture or by decapitation. After cardiac puncture, AE levels were in the low-nanomolar range: anandamide, 3.1 +/- 0.6 pmol/ml; PEA, 9.4 +/- 1.6 pmol/ml; OEA, 9.2 +/- 1.8 pmol/ml (mean +/- SE, n = 9). By contrast, after decapitation AEs were dramatically elevated (anandamide, 144 +/- 13 pmol/ml; PEA, 255 +/- 55 pmol/ml; OEA, 175 +/- 48 pmol/ml). Thus, disruptive procedures of blood collection may result in gross overestimates in the concentrations of circulating AEs.     

Factors affecting the free fatty acids in rat brain cortex

The mode of free fatty acid (FFA) release from rat brain cortex was examined under various treatments prior to decapitation and at various times after decapitation. Brain FFA are comprised mainly of 16:0, 18:0, 18:1 and 20:4 with smaller amounts of 18:2, 22:4 and 22:6. A biphasic mode of FFA release is observed with respect to post-decapitative ischemic treatment. The initial rapid phase involves a 3-fold increase in 18:0 and 20:4 and this process occurs within the first min of decapitation. The second phase involves a less rapid increase of most fatty acids between 2 and 5 min after decapitation. Besides the ischemia-induced increase in brain FFA, the levels of individual fatty acids are also affected by factors such as handling stress and administration of anesthetic agents. Pentobarbital anesthesia, but not ketamine, caused a partial reduction in 18:0 and 20:4 levels in brain in vivo. Pentobarbital treatment also reduced the rapid phase of FFA increase commencing after decapitation. On the other hand, FFA level was higher in animals subjected to ketamine anesthesia, both during the non-ischemic and ischemic phase. Results obtained from this study indicate that the FFA pool in brain is regulated by a complex mechanism contributed by extrinsic and intrinsic factors.     

大鼠肺鳞癌模型两种麻醉方法的比较

目的探讨不同麻醉方法建立大鼠肺鳞癌模型的差异。方法体重180～220g Wistar大鼠,依不同麻醉方法分为2组：实验Ⅰ组（110只）用0．3％戊巴比妥钠麻醉;实验Ⅱ组（80只）基础麻醉用盐酸氯胺酮44mg／kg,然后乙醚吸入麻醉。两组均采用额镜直视法,灌注3-甲基胆蒽（MCA）、二乙基亚硝胺（DEN）与普通碘油混悬液于大鼠左下叶支气管。结果麻醉显效时间和维持时间分别为：Ⅰ组,（23．50±1．98）min,（246．56±15．46）min,Ⅱ组,（3．05±0．45）min,（12．47±1．35）min,两组间有显著性差异（P〈0．01）;灌注成功率、存活率、诱癌率分别为：Ⅰ组94．55％,48．08％,90．00％,Ⅱ组93．75％,90．67％,92．65％,两组成功率、诱癌率差异无显著性（P〉0．05）,存活率有显著差异（P〈0．01）。分别于不同时间处死大鼠,2组基本病理过程相同。结论戊巴比妥钠麻醉剂量易控制,以小剂量灌注雄性大鼠为佳;盐酸氯胺酮与乙醚复合麻醉较难控制,但速度快,实用性强。     

Plasma glucocorticosteroid and aldosterone levels during physiological and stress conditions in rabbits. II. adult animals

The pattern of adrenal steroid secretion under basal and stress conditions and the response to tetracosactid (20.0 micrograms/kg body weight) were studied in adult male rabbits. In animals repeatedly stressed by artery puncture, plasma glucocorticosteroid levels were slightly higher than those found in unstressed control animals. The combined stress of repeated exposure to ether vapor for 60 sec, followed by artery puncture, significantly stimulated glucocorticosteroid release, concentrations progressively increasing with the number of ether exposures applied. A much faster and more pronounced stimulation of glucocorticosteroid release was seen in animals treated with 20.0 micrograms/kg body weight tetracosactid. Plasma aldosterone levels in animals stressed by artery puncture were higher, although not significantly, than those of unstressed control animals. Repeated exposure to ether vapor for 60 sec, followed by artery puncture, on the other hand slightly decreased plasma aldosterone concentrations. A strong stimulation of aldosterone release at 20--60 min after injection could be elicited only by intravenous administration of 20.0 micrograms/kg body weight tetracosactid. Because of the insensitivity of the zona glomerulosa cells to increased ACTH levels under stress conditions, it is concluded that ACTH is only of minor importance both under basal and stress conditions in the regulation of aldosterone secretion in the rabbit.     

Endocrine stress response in jugular-vein cannulated rats upon multiple exposure to either diethyl-ether, halothane/O2/N2O or sham anaesthesia

The main objective of this study was to assess the endocrine stress response to multiple anaesthesia followed by sham anaesthesia in order to detect any memory effects. For this purpose, jugular-vein cannulated rats were subjected to either sham, diethyl-ether or halothane/O2/N2O anaesthesia, and their plasma ACTH, corticosterone, glucose, adrenaline and noradrenaline levels measured. The study had three separate experiments, each consisting of a control and treatment group. In two experiments, the rats were exposed to high or low concentrations (40-15%) of diethyl ether, using either a jar containing cotton soaked in diethyl ether or a vaporizer. In the third experiment, rats were exposed to halothane/O2/N2O. Control animals underwent sham anaesthesia. Blood samples were taken 6 min before and at 5, 15 and 55 min after starting the exposure (t = 0 min). For each variable, the dt5 (level at t = 5 min minus that at t = -6 min) and the cumulative levels over the one-hour period as determined by the area under the curve (AUC) were calculated. Further, the peak levels (Cmax) were determined. The mean time needed to induce anaesthesia was 68, 121 and 55 s for exposure to high and low concentrations of diethyl ether and to halothane/O2/N2O, respectively. Increased noradrenaline and adrenaline dt5 levels were observed only after the first exposure to the high concentration of diethyl ether. Multiple anaesthesia sessions using either diethyl ether or halothane/O2/N2O did not clearly influence adrenaline and noradrenaline levels. Diethyl ether induced a sharp rise in plasma ACTH and glucose levels, irrespective of the concentration used. The response of the ACTH and glucose was similar for single and multiple exposure. An increased response of ACTH, corticosterone and glucose to sham anaesthesia following multiple induction of anaesthesia was observed for the high concentration of diethyl ether only. Halothane/O2/N2O raised plasma glucose without differences between single and multiple anaesthesia sessions. Upon sham anaesthesia following multiple exposures to halothane/O2/N2O, glucose levels were significantly increased. This study indicates that repeated anaesthesia in rats can elicit an increased stress response during subsequent handling and change of environment.     

Effect of selenium-enriched malt on VEGF and several relevant angiogenic cytokines in diethylnitrosamine-induced hepatocarcinoma rats

One hundred and ninety-three Sprague–Dawley (SD) rats (average body weight 100–120 g) were randomly divided into five groups (I–V). Groups I and II rats served as the negative and positive controls respectively and both received 0.1 mg/kg Se from sodium selenite supplemented diets for the 18-week experimental period. Groups III–V rats were fed Se from SEM supplemented diets (0.3, 1 and 3 mg/kg respectively). To induce hepatocarcinoma, groups II–V rats received diethylnitrosamine solution (100 mg/L) at the dosage of 10 mg/kg body weight in drinking water daily for 16 weeks, followed by sterilized water for a further 2 weeks. Group I rats received sterilized water throughout. At weeks 4, 8, 12 and 16 five rats in each group were sacrificed by cervical decapitation. At the termination of the study, at week 18, the surplus rats were sacrificed by cervical decapitation. Feed was withheld from the rats for 12  h before sampling. The following items including TNF-α, IGF-II, NO and T-NOS levels in plasma were tested using kit techniques. At the same time the expression of vascular endothelial growth factor (VEGF) in tumor tissue was analyzed by immunohistochemistry using the envision two-step methods with a kit. The results indicated that SEM could increase the levels of TNF-α in the early stages of hepatocarcinoma formation, however there was a decrease in the later stage of hepatocarcinogenesis. SEM could also significantly decrease the levels of IGF-II and NO, and inhibit the expression of VEGF in tumor tissue. SEM delayed the development of hepatocarcinoma in rats and that could be partially attributed to inhibition of angiogenesis.     

Four methods for general anaesthesia in the rabbit: a comparative study

The efficacy and safety of pentobarbitone, ketamine/xylazine, fentanyl/fluanisone/diazepam, and halothane/nitrous oxide anaesthesia were compared in 4 groups of six New Zealand White rabbits. Heart and respiratory rates, body temperature, reflexes, blood pressure and blood gases were measured. Pentobarbitone appeared to be unsuitable for anaesthesia in rabbits, as 5 of the 6 rabbits to whom it was administered, required artificial respiration or died. The combinations of ketamine/xylazine and fentanyl-fluanisone/diazepam both produced unpredictable levels of anaesthesia together with a substantial decline in arterial blood pressure and PO2. Despite a severe drop in blood pressure (up to 37.5%), anaesthesia with halothane and nitrous oxide was found to be superior to the other anaesthetic agents.