Article

IV infusion of a drag-reducing polymer extracted from aloe vera prolonged survival time in a rat model of acute myocardial ischaemia

Department of Anesthesiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
BJA British Journal of Anaesthesia (Impact Factor: 4.35). 02/2007; 98(1):23-8. DOI: 10.1093/bja/ael307
Source: PubMed

ABSTRACT I.V. infusion of drag-reducing polymers (DRPs) has been shown to improve survival time in animals subjected to haemorrhagic shock. We hypothesized that DRPs might prolong survival time in rats following acute myocardial ischaemia (AMI).
Sixteen adult male rats were anaesthetized and mechanically ventilated. An i.v. infusion of either Dextran-40 2.5% (Control, n=8) or Dextran-40 2.5% containing 50 microg ml(-1) of an aloe vera-based DRP (DRP, n=8) was initiated at 3.5 ml h(-1). The left anterior descending coronary artery was ligated. Blood pressure, skin-tissue perfusion, and heart rate were monitored and arterial blood samples were analysed.
The mortality at 60 min following coronary ligation was 0% in the DRP group vs 50% in the control group (P=0.025). DRP-treated animals maintained higher mean arterial pressure [60.9 (5.1) vs 47.5 (5.1) mm Hg, P=0.004] and tissue perfusion [4.2 (3.4) vs 1.2 (0.5) TPU, P=0.029]. The DRP group trended towards better acid-base status with base excess [-5.0 (1.7) vs -8.1 (5.1) mmol litre(-1), P=0.083] and pH [7.42 (0.07) vs 7.35 (0.02), P=0.03].
Administration of nanomolar concentrations of aloe vera-based DRP prolonged survival time in animals with AMI. DRPs may offer a novel method to treat organ/tissue hypoperfusion.

Download full-text

Full-text

Available from: Tetsuro Sakai, Mar 24, 2014
0 Followers
 · 
96 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Recent studies have shown that drag-reducing polymers (DRPs) prolonged survival time in rats with acute myocardial infarction (MI), but their effect on cardiac function post MI remains unknown. This study sought to test the hypothesis that intravenous infusion of DRPs may improve left ventricular (LV) function in rats following surgically induced MI. MI was induced by ligation of the left anterior descending coronary artery in 36 Sprague-Dawley rats, and sham operations were performed in 12 animals. DRPs were then administered to 18 of the MI rats. Echocardiograpy was used to evaluate the changes of impaired LV function and global wall motion. Besides, the hydrodynamic effect of DRPs on microcirculation was also assessed. The survival rate at 24h following MI was significantly different among the sham, MI and DRP groups (p = 0.023). DRP-treated animals had marked smaller left ventricular end-systolic diameter and better anterior systolic wall thickness comparison with untreated rats. Significant improvement of fractional shortening and ejection fraction were detected in MI rats with DRP. Wall motion score index and contrast score index were both significantly reduced by DRP treatment. DRPs were shown to have beneficial effects on microvascular variables including red blood cell velocity, diameter, blood flow and calculated wall shear stress in third-order arteriole. Acute administration of DRPs improved LV function in a rat model of MI possibly by improving microvascular blood flow due to their unique hydrodynamic properties. DRPs may offer a new approach to the treatment of coronary artery ischemic diseases.
    International journal of cardiology 02/2011; 147(1):112-7. DOI:10.1016/j.ijcard.2010.09.008 · 6.18 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper reports a novel, physiologically significant, microfluidic phenomenon generated by nanomolar concentrations of drag-reducing polymers (DRP) dissolved in flowing blood, which may explain previously demonstrated beneficial effects of DRP on tissue perfusion. In microfluidic systems used in this study, DRP additives were found to significantly modify traffic of red blood cells (RBC) into microchannel branches as well as reduce the near-wall cell-free layer, which normally is found in microvessels with a diameter smaller than 0.3 mm. The reduction in plasma layer size led to attenuation of the so-called "plasma skimming" effect at microchannel bifurcations, increasing the number of RBC entering branches. In vivo, these changes in RBC traffic may facilitate gas transport by increasing the near vessel wall concentration of RBC and capillary hematocrit. In addition, an increase in near-wall viscosity due to the redirection of RBC in this region may potentially decrease vascular resistance as a result of increased wall shear stress, which promotes endothelium mediated vasodilation. These microcirculatory phenomena can explain the previously reported beneficial effects of DRP on hemodynamics in vivo observed in many animal studies. We also report here our finding that DRP additives reduce flow separations at microchannel expansions, deflecting RBC closer to the wall and eliminating the plasma recirculation zone. Although the exact mechanism of the DRP effects on RBC traffic in microchannels is yet to be elucidated, these findings may further DRP progress toward clinical use.
    Biorheology 02/2009; 46(4):281-92. DOI:10.3233/BIR-2009-0543 · 1.59 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We tested the hypothesis that the infusion of a small volume of a drag-reducing polymer (DRP) solution can prolong survival in rats subjected to lethal hemorrhagic shock (HS; shed 51% of estimated blood volume) in the absence of complete resuscitation with fluids or blood. In this set of experiments, we used a newly designed mixture of hyaluronic acid (molecular weight, approximately 2.0 x 10 d; 0.4 mg/mL) and polyethylene oxide (molecular weight, approximately 4 x 10 d; 0.05 mg/mL) dissolved in sterile phosphate-buffered saline. Anesthetized rats were subjected to a volume-controlled HS. During the first 20 min, blood (21.7 mL/kg) was withdrawn. During the next 40 min, additional blood (14 mL/kg) was withdrawn, and during the final 20 min, saline vehicle or saline + DRP (2.8 mL/kg) was simultaneously infused. The survival rate of the rats treated with the hyaluronic acid/polyethylene oxide was significantly higher (P < 0.01). The mean survival times for control and DRP-treated animals were 100.4 +/- 9.5 vs. 154.8 +/- 7.0 min (P < 0.001). MAP was higher (P < 0.005) and skin perfusion was significantly improved in the DRP-treated group after the end of the DRP infusion. These results support the use of nanomolar concentrations of DRP to prolong survival in rats after lethal HS in the absence of fluid resuscitation. The DRP formulation studied here warrants further evaluation for the amelioration of critical illness associated with profound shock when access to resuscitation fluids may not be possible or delayed.
    Shock (Augusta, Ga.) 03/2009; 31(3):258-61. DOI:10.1097/SHK.0b013e31817fc434 · 2.73 Impact Factor