Effect of graded doses of naloxone on renal function in canine hemorrhagic shock.

All the parameters of renal function (inulin clearance, para amino hippuric acid clearance and urine flow) which were depressed during experimentally induced hemorrhagic shock in dogs improved significantly in addition to improvement in mean arterial pressure (MAP) after bolus administration (iv) of 1 or 2 mg/kg naloxone. A smaller dose (0.5 mg/kg) of naloxone, however, did not improve the renal function. Even renal arterial injection of the same dose of naloxone showed no improvement in the renal function. In both these cases the improvement in the MAP was significantly less as compared to other groups of animals which received 1 or 2 mg/kg naloxone. It may be concluded that (a) naloxone at doses of 1 or 2 mg/kg improved the renal function by improving MAP and (b) naloxone has no direct action on renal vasculature.     

Effect of opiate receptor agonists on the course of hemorrhagic shock in rats

The experiments have been performed on 93 male rats, weighing 200-250 g. In acute blood loss various arterial pressure (AP) changes have been demonstrated--the marked hypertension is being changed by gradual AP increase. The injection of m-receptors' agonist DAGO prevents systolic and diastolic AP increase, agonist DADL prevents diastolic AP increase in acute momentary blood loss. In gradual blood loss DAGO (more than DADL) slows down both the decrease and the subsequent AP increase in rats. DAGO is determined to decrease, and DADL--to increase the minute blood volume. The mechanisms of opioids' action and their significance in pathogenesis of hemodynamic disturbances in shock are being discussed.     

不同液体复苏对失血性休克大鼠肠粘膜的影响

目的：观察不同液体复苏对失血性休克大鼠肠粘膜的影响以及肠粘膜的变化。方法：利用大鼠失血性休克模型以及不同的补液方式,在复苏后120分钟时处死大鼠,取回肠4cm,做病理切片并根据Chiu等方法评估回肠黏膜上皮损伤指数。结果：液体复苏组的肠粘膜损伤程度小于休克不补液组（p〈0.05）,而限制型液体复苏组的肠粘膜损伤程度小于充分液体复苏组（p〈0.05）。结论：通过本实验对肠粘膜的观察可以得出,对于失血性休克,液体复苏时有效的抗休克方式,而对于复苏的方式来说,从肠黏膜的保护方面来说,限制型液体复苏是优于传统的充分液体复苏的。     

不同液体复苏对失血性休克大鼠肠粘膜的影响

目的:观察不同液体复苏对失血性休克大鼠肠粘膜的影响以及肠粘膜的变化。方法:利用大鼠失血性休克模型以及不同的补液方式,在复苏后120分钟时处死大鼠,取回肠4cm,做病理切片并根据Chiu等方法评估回肠黏膜上皮损伤指数。结果:液体复苏组的肠粘膜损伤程度小于休克不补液组(p<0.05),而限制型液体复苏组的肠粘膜损伤程度小于充分液体复苏组(p<0.05)。结论:通过本实验对肠粘膜的观察可以得出,对于失血性休克,液体复苏时有效的抗休克方式,而对于复苏的方式来说,从肠黏膜的保护方面来说,限制型液体复苏是优于传统的充分液体复苏的。     

Effects of naloxone on regional blood flow distribution in canine hemorrhagic shock

The opiate antagonist naloxone increases arterial pressure, maximal left ventricular dp/dt and cardiac output when administered to dogs subjected to hemorrhagic shock. The purpose of this study was to investigate regional blood flow changes associated with naloxone treatment in anesthetized hypovolemic and normovolemic dogs. Hypovolemic dogs (n = 10) were bled over 30 min (t = -30 to t = 0) to a pressure of 45 mm Hg which was maintained for 1 hr. At t = 60, five dogs received naloxone (2 mg/kg + 2 mg/kg X hr), and five received an equal volume of saline. Regional blood flows were determined at t = -30, 45, and 90 min using 15-micron microspheres. Normovolemic dogs (n = 10) were subjected to the same protocol except they were not bled. During hypovolemia, naloxone produced significant increases in myocardial, intestinal, hepatic, and adrenal blood flows whereas saline treatment did not. No significant changes in skin, muscle, fat, pancreatic, renal, or brain flows were detected. The increases in blood flow were not associated with significant changes in vascular resistance. Naloxone had no significant effects on any hemodynamic parameter during normovolemia. The beneficial effects of naloxone in hemorrhagic shock include increased blood flow to vital organs due to increased perfusion pressure which is secondary to improved cardiac performance.     

Comparison of effects of naloxone and catecholamines on acid-base balance in canine hemorrhagic shock

The present study was conducted to compare the effect of naloxone, an opiate receptor antagonist, with catecholamines on acid-base status and survival in dogs subjected to hemorrhagic shock. Arterial lactic acid concentration which had increased during hemorrhage, decreased significantly (P less than 0.05) in naloxone treated animals but increased further in catecholamine treated dogs. Blood bicarbonate concentration and PCO2 which had markedly decreased 1 hr after hemorrhage recovered significantly (P less than 0.05) in naloxone group of animals. On the other hand bicarbonate and pH declined further in noradrenaline group and remained unchanged in dopamine group. These results as well as better survival rate observed in naloxone treated animals suggest the superiority of naloxone over dopamine and noradrenaline, as an adjunct to blood transfusion in the treatment of hemorrhagic shock.     

Effect of naloxone on renal cortical microcirculation in haemorrhagic shock

In order to assess the effect of opioid receptor antagonists, naloxone and noradrenaline, on renal cortical microcirculation, India ink infusion was made through the renal artery, one hour after treatment with each drug, in dogs subjected to haemorrhagic shock. Naloxone (1 mg/kg) treatment showed a dual beneficial effect of significant improvement (P < 0.001) in the mean arterial pressure without increasing the renal resistance as indicated by the presence of ink particles in about 75% of the cortical glomeruli. However, in the case of noradrenaline (2 Μ/kg/min)-treated animals, although mean arterial pressure increased significantly (P < 0.001) only very few glomeruli (25%) in the cortical region showed ink particles, demonstrating severe vasoconstriction. In the control group infused only with saline, although most of the glomeruli (92%) were filled with ink particles, there was a significant decline in the mean arterial pressure (P < 0.001).     

Effect of naloxone on blood microcirculatory changes in anaphylactic shock

During the experiment conducted upon 85 guinea-pigs it has been found that the injection of naloxone at the dose of 0.5 g/kg half an hour before the reproduction of anaphylactic shock (AS) by the use of horse serum increases the number of cases of the retarded development of pathological reaction and survival of the animals. Except for the quantitative differences mentioned any peculiarities characterizing the effect of naloxone were not found. As to the morphological differences of variants in the course of AS they are distinctly defined only at the analysis of film preparations of the intestinal mesentery. The typical AS becomes apparent by haemorrhages, by dilatation of all the vessels of blood circulation and by forming of erythrocytic aggregates in them. At the retarded development of AS a spasm of precapillaries is observed. After convalescence of the animals the aggregates of erythrocytes can be revealed only in venules. Studying the animals recovered after AS one can find that for a long time these animals had the erythrocytic aggregates in the clearances of venules, as well as the signs of new formation of the capillaries.     

A new model of severe hemorrhagic shock in rats

We here introduce a fixed-pressure model of hemorrhagic shock in rats that maximizes effects on mean arterial blood pressure (MAP) during shock and yet maintains high reproducibility and controllability. The MAP of rats was adjusted to 25 to 30 mm Hg by blood withdrawals during 30 min. After a shock period of 60 min, rats were resuscitated either with lactated Ringer solution (LR) only or with the collected blood 3-fold diluted with LR (LR + blood) and monitored for further 150 min. Throughout the experiment, vital parameters and plasma marker enzyme activities and creatinine concentration were assessed. Thereafter, liver, kidneys, small intestine, heart, and lung were harvested and evaluated histopathologically. Vital parameters, plasma marker enzyme activities, creatinine concentration, and histopathology indicated pronounced but reliable and reproducible systemic effects and marked organ damage due to hemorrhagic shock and resuscitation. In contrast to rats that received LR + blood, which survived the postresuscitation period, rats receiving LR only invariably died shortly after resuscitation. The hemorrhagic shock model we present here maximally affects MAP and yet is highly reproducible in rats, allowing the study of various aspects of hemorrhagic shock and resuscitation under clinically relevant conditions.     

大鼠失血性休克后肠道微生态的改变

本研究对无特殊致病菌大鼠失血性休克后肠道微生态的改变及肠道细菌易位进行了动态观察。结果表明,失血性休克复苏后5小时,肠道微生态即发生改变,表现为回肠内肠杆菌菌量增多,肠道内类杆菌与肠杆菌菌量比值下降,而后这一改变随时间推移逐渐恢复;肠道细菌易位率也有类似变化,易位细菌以肠杆菌为主。结果提示,大鼠失血性休克后肠道细菌易位与肠道微生态的改变有密切关系。     

Effect of different doses of chromium picolinate on protein metabolism in infant rats.

This 12-day study was conducted to evaluate the effects of three different levels of dietary chromium (100, 200, and 500 microg/day) in the form of chromium picolinate (CrPic) on growth and protein use in weaned rats. No significant effect of CrPic on body weight gain, food intake, or food conversion rate was observed. Elevated doses of CrPic seemed to increase muscle mass, either by stimulating protein anabolism by activation of insulin by chromium or by lowering protein degradation. However, these effects had no repercussions on overall growth, suggesting that any anabolic effect of chromium due to the action of insulin was probably marginal.     

The physiological changes of cumulative hemorrhagic shock in conscious rats

Summary Hemorrhagic shock is a common cause of death in emergency rooms. Current animal models of hemorrhage encounter a major problem that the volume and the rate of blood loss cannot be controlled. In addition, the use of anesthesia obscures physiological responses. Our experiments were designed to establish an animal model based on the clinical situation for studying hemorrhagic shock. Hemorrhagic shock was induced by withdrawing blood from a femoral arterial catheter. The blood volume withdrawn was 40% of the total blood volume for group 1 and 30% for group 2 and 3. Group 3 was anesthetized with sodium pentobarbital (25 mg/kg, i.v.) at the beginning of blood withdrawal. Our data showed that the survival rate was 87.5% at 48 h in the conscious group and 0% at 9 h in anesthetic group after hemorrhage. The levels of mean arterial pressure, heart rate, white blood count, TNF-, IL1-, CPK, and LDH after blood withdrawal in the anesthetic group were generally lower than those in conscious groups. These results indicated that anesthetics significantly affected the physiology of experimental animals. The conscious, unrestrained and cumulative volume-controlled hemorrhagic shock model was a good experimental model to investigate the physical phenomenon without anesthetic interfernce.     

Effect of naloxone on physostigmine-induced pressor response in adrenalectomized rats

Physostigmine-induced pressor response was studied in adrenalectomized rats. The increase in mean arterial blood pressure elicited by intravenous administration of physostigmine was not altered by adrenalectomy or sham-operation. The pressor response to intracerebroventricular administration of physostigmine was found to be partially inhibited in both acutely adrenalectomized and sham-operated rats, but not in those adrenalectomized 24 h earlier. This inhibition was completely prevented by naloxone pretreatment. The results suggest that endogenous opioid peptide release induced by surgical stress may be responsible for inhibition of the pressor effect of centrally administered physostigmine in rats.