Chávez-Negrete A, Oropeza M V, Rojas M M, Villanueva T, Campos M G
Research Unit, Cardiology Hospital, National Medical Center, Mexico City, Mexico.
Artif Cells Blood Substit Immobil Biotechnol. 2004;32(4):549-61. doi: 10.1081/bio-200039616.
Blood substitutes are being developed using molecular solutions of modified free hemoglobin; however, anaphylactic reactions, severe renal toxicity, and hypertension have been reported in experimental models and human beings. Hypertension remains as an obstacle to the clinical use of most blood substitutes. Several investigators suggest that this effect is due to the interaction between nitric oxide and hemoglobin into the endothelial cells; hence, prevention of hemoglobin extravasation would avoid vasoconstriction. The forms of hemoglobin likely to prevent extravasation include polymerized and encapsulated Hb. Another alternative and significantly less expensive approach is the hydroxyethyl starch Hb-polymer. The aim of the present study was to compare the effect of hydroxyethyl-starch-hemoglobin with that of stroma-free hemoglobin on the in vitro contractile activity of aortic rings isolated from adult male rats.
The hemoglobin-based oxygen carrier was made using stroma-free hemoglobin prepared from outdated human red cells and conjugated with 10% hydroxyethyl starch 200-260 MW. The experiments were made in thoracic segments of the aortic rings incubated with hemoglobin, starch-hemoglobin or Ringer Krebs-Bicarbonate solution (RKB) during 30 min. Smooth muscle contraction with phenylephrine and subsequent inhibition of contraction with carbachol were performed before and after incubation with hemoglobin, starch-hemoglobin, or vehicle.
Incubation with hemoglobin and starch-hemoglobin significantly increased the contractile response to phenylephrine of aortic rings compared with RKB solution. The maximal response to carbachol was significantly decreased in the aortic rings incubated with either hemoglobin or starch-hemoglobin in comparison with the RKB-incubated tissues. There were no differences between the aortic rings incubated with either hemoglobin, or starch-hemoglobin.
These results show that there are no differences between the effects of stroma-free hemoglobin and starch-hemoglobin on the in vitro contractile activity of aortic rings isolated from adult male rats. Our findings do not support the hypothesis that an increase in the size of the hemoglobin molecule prevents hemoglobin extravasation, and the consequent vasoconstriction due to the scavenging of nitric oxide by stroma free hemoglobin in the cellular space between endothelium and smooth muscle.
正在利用修饰的游离血红蛋白的分子溶液研发血液替代品；然而，在实验模型和人类中已报道了过敏反应、严重肾毒性和高血压。高血压仍然是大多数血液替代品临床应用的障碍。一些研究人员认为，这种效应是由于一氧化氮与血红蛋白在内皮细胞中的相互作用所致；因此，防止血红蛋白外渗可避免血管收缩。可能防止外渗的血红蛋白形式包括聚合血红蛋白和包封血红蛋白。另一种成本显著更低的方法是羟乙基淀粉血红蛋白聚合物。本研究的目的是比较羟乙基淀粉血红蛋白与无基质血红蛋白对成年雄性大鼠离体主动脉环体外收缩活性的影响。
基于血红蛋白的氧载体采用从过期人红细胞制备的无基质血红蛋白，并与10%分子量为200 - 260的羟乙基淀粉偶联制成。实验在主动脉环的胸段进行，将其与血红蛋白、淀粉血红蛋白或林格氏碳酸氢盐溶液（RKB）孵育30分钟。在用血红蛋白、淀粉血红蛋白或溶剂孵育之前和之后，用去氧肾上腺素诱导平滑肌收缩，随后用卡巴胆碱抑制收缩。
与RKB溶液相比，用血红蛋白和淀粉血红蛋白孵育显著增加了主动脉环对去氧肾上腺素的收缩反应。与用RKB孵育的组织相比，用血红蛋白或淀粉血红蛋白孵育的主动脉环对卡巴胆碱的最大反应显著降低。用血红蛋白或淀粉血红蛋白孵育的主动脉环之间没有差异。
这些结果表明，无基质血红蛋白和淀粉血红蛋白对成年雄性大鼠离体主动脉环体外收缩活性的影响没有差异。我们的研究结果不支持以下假设：血红蛋白分子大小的增加可防止血红蛋白外渗，以及由此导致的由于无基质血红蛋白在内皮和平滑肌之间的细胞间隙中清除一氧化氮而引起的血管收缩。
