| Objective To explore the early effect of the different resuscitative fluids in the rat models of septic shockMethod Seventy-two male Sprague-Dawley(SD) rats were randomly divided into nine groups with 8 rats in each group (n=8, respectively);①group A (septic shock group): Eight rats in this group were administered endotoxin by external jugular vein injection, blood pressure, blood gas analysis and blood lactic acid were measured, histological changes of the heart and lung were observed.②group B(saline group): Eight rats in this group were administered saline(20ml/kg) by Intravenous push for 20min.③group C(low molecular weight dextran group): Eight rats in this group were administered low molecular weight dextran(20ml/kg) by Intravenous push for 20min.④group D(albumin group): Eight rats in this group were administered 5% albumin(20ml/kg) by Intravenous push for 20min.⑤group E(saline united low molecular weight dextran group): Eight rats in this group were administered saline(10ml/kg) and low molecular weight dextran(10ml/kg) by Intravenous push for 20min.⑥group F(saline united albumin group): Eight rats in this group were administered saline(10ml/kg) and 5% albumin(10ml/kg) by Intravenous push for 20min.⑦group G(low molecular weight dextran united albumin group): Eight rats in this group were administered low molecular weight dextran(10ml/kg) and 5% albumin(10ml/kg) by Intravenous push for 20min.⑧group H (united all of three group): Eight rats in this group were administered saline(10ml/kg), low molecular weight dextran(5ml/kg) and 5% albumin(5ml/kg) by Intravenous push for 20min.⑨group I(normal control group): no any special intervention to this group of eight rats, only blood pressure, blood gas analysis and blood lactic acid were measured, histological changes of the heart and lung were observed. After administered endotoxin by external jugular vein injection, the blood pressure of fifty-five rats in eight groups (except control group) reduced into the state of shock. Nine rats didn't reduce or even elevated, those endotoxin resistance rats were finally excluded.Real time monitoring of mean arterial pressure (MAP) were performed to all groups of rats,and basic blood pressure, shock blood pressure and blood pressure after resuscitation were measured to the end of the first hour.When MAP reached no less than 90% of the basic blood pressure and lasted for 10min or longer,the rats were successfully resuscitated.The ratio of successful resuscitation, the time needed for reach the target blood pressure, blood gas analysis, blood lactic acid between each groups were performed. The heart and lung were collected,and histological changes were observed under the light and electron microscope respectively.Result Compared success ratio and the effective time of resuscitation of group B with group C , group D and group G were all P <0.05. Compared PH value of group A with group D and group G were all P <0.05. Compared advantages in raising partial pressure of oxygen of group A with group B were all P <0.05. Compared blood lactate values of group A with group B and group F were all P <0.05. The morphologic change of myocardiac tissue injury of group A was obviously observed with light microscopy, large areas of myocardial necrosis could be seen, some cardiac cells completely melt, the structure couldn't be resolved, myocardial interstitial vascular dilation, congestion significantly, inflammatory cells exfiltrated. Alveolar structure of lung disorders, interval widened, alveolar wall structural damaged, with focal atelectasis, partial alveolar collapse. Perivascular and alveolar infiltration with inflammatory cells and exudates. Observed with electron microscopy, myocardial fibers were disordered, filaments broked and dissolved, the gap widened, Z-band fuzzied and disappeared; mitochondrial proliferated, swelled like ballooning, a kind of dense floc and vesicular mitochondrial were formated, the mitochondria cristae were disappeared. The nucleus inlarged and edemaed, concentration, margination and fragmentation were found in the nuclear chromatin, irregularity were found in nuclear membrane. Mitochondrial swelling, cristae reduced or even disappeared, lamellar body severely vacuolated, nuclear shrinked, chromatin marginated. Under light microscope, normal cardiac muscle fibers were observed, part nucleus of the myocardial cells disappeared, and no obvious necrosis and inflammatory cell response were observed. The basic integrity of lung tissue structure were normal, the alveolar cavity were clean and clear, without any obvious inflammatory reaction in the rats of group B. Under electron microscope, sarcomere banding were clear, the myofibrils were basal integrated; mitochondrial swelling slightly increased, the nucleus integrated, clearand and no swelling, membranes were integrated, and chromosome nucleolus were clearly observed, closing to the normal myocardial structure; The mitochondria and lamellar body of lung were normal, nuclear slightly inlargered, membrane were normal, close to the normal lung tissue structure. Compared with saline group, the other groups had no advantages of pathological improvement under light microscopy and electron microscopy.Conclusion This study verificates that Serious heart and lung damages are existent in the early stage of septic shock in rats. Whether used alone or in combination, colloid (albumin and the low molecular weight dextran) has poorer effects on increacing blood pressure, and has lower success ratio of resuscitation and longer recovery time than the crystalloid or the combination of the crystalloid and the colloid in the first hour of fluid resuscitation; As acid PH value of the base material in the improvement of the buffer, albumin has its advantages, while crystalloid is more conducive to raising partial pressure of oxygen, lower blood lactate values, improve microcirculation perfusion; Saline groups has more advantages than the other liquids and combinations in histological improvement.
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