Studies On The Hypoxia Adaptation Of Gansu Zokor

Gansu zokor is a unique subterranean rodent which lives on the loessplateau of our country. Living in the hypoxia underground environment for long term,it developed many special adaptive characters on configuration and function to adaptits special circumstances. We studied the blood viscosity characters and theexpression of HIF-1a, EPO and VEGF of Gansu zokors under hypoxia conditions andcompared with SD rat trying to find the hypoxia adaptive mechanisms of Gansuzokors. The results are as follows:1. Hemorheological indexs of acute hypoxia group of zokors all increased, buthave no statistical meaning (P＞0.05) compared with normoxia group. And thehemorheological indexs of chronic hypoxia group of zokors all significantly increasedcompared with the normoxia group (P＜0.01).Compared with normoxia group, acute hypoxia induced hyperviscosity in rat thattheηb-m,ηr,ηp, blood yield stress, AI and RI are all elevated significantly (P＜0.01 orP＜0.05). TK significantly decreased (P＜0.01) in chronic hypoxia group of rat thannormoxia group, and HCT, K, RI (P＜0.01) andηp increased significantly (P＜0.05).All hemorheological indexs of normoxia and acute group of rats significantlyincreased (P＜0.05 or P＜0.01) than zokor exceptηp and PFC. Theηb-h,ηb-m, HCTand K of chronic group of rats is significantly higher than zokors (P＜0.05), and otherhemorheological indexs have no statistical differences.2. Different characters of the hemorheology of zokors and rats incarnate at threeaspects as follows:â‘ Hemorheological indexs of zokors are very low in normoxia,thus they have much higher endurance to the increasing of hemorheological indexswhen affront hypoxia. And their RBC numbers and HCT increase along with it, resultin the increasing of the ability of the blood to carry more O₂ to tissues. And heartfunctions of zokors also reinforce at hypoxia. These may be the hypoxia adaptivemechanisms of zokors.â‘¡Effects of hypoxia to the TK are different in these twoanimals. TK increase in zokors and decrease in rats in hypoxia.â‘¢Effects of hypoxiato theηp are different that theηp of the acute and chronic hypoxia groups of rats aresignificantly higher than normoxia group (P＜0.05), and there no statistical differencesin the three groups of zokors (P＞0.05).3. Study of the RBC metamorphosis show that the SEM configuration of zokors always keeping normal, and it distort in rats at hypoxia that it much severe in acutehypoxia. Hypoxia has no significant effects on the SEM configuration of zokors, andthe increasing of RBC numbers must contribute to their hypoxia adaptive abilities.4. HIF-1a were expressed abroad in the tissues of zokors under nornoxia. Levelsof HIF-1a in the brain, liver and kidney of normoxia group of zokors are 14.82, 24.75and 14.00 times that of rats (P＜0.01). There are no significant differences of HIF-1alevel between normoxia group and acute hypoxia group of gansu zokors(P＞0.05).Expression levels in the brain, liver and kidney of acute hypxia group of zokors are4.59, 3.17 and 3.09 times that of rats (P＜0.01).Levels of HIF-1a in the brain, liver andkidney of chronic hypoxia group of zokors is 4.13, 3.38 and 4.40 times that ofnormoxia group separately (P＜0.01). Levels of HIF-1a in the brain, liver and kidneyof chronic hypoxia group of zokors is 2.30, 2.25 and 2.79 times that of rats(P＜0.01).Broad expression of HIF-1a under normoxia in zokors may be one of itshypoxia adaptive mechanisms.There are nearly no expression of HIF-1a in the brain of rats under normoxia,and it elevated in acute hypoxia (P＜0.01), and elevated further in chronic hypoxia andexpressed abroad in the whole brain (P＜0.01). Levels of HIF-1a in the liver andkidney of the acute hypoxia group of rats are 9.12 and 7.68 times that of normoxiagroup (P＜0.01). Levels of HIF-1a in the liver and kidney of the chronic hypoxiagroup of rat is 33.17 and 22.09 times that of normoxia group (P＜0.01).5. Under normoxia, there are no significant differences of the EPO expressionlevel between zokors and rats in the brain (P＞0.05), and levelsin the liver and kidneyin zokors are 1.31 (P＜0.01)and 1.17 times (P＜0.05) that of rats. In acute hypoxiagroup, EPO levels in the brain, liver and kidney are 3.58, 3.35 and 4.10 times that ofnormoxia group (P＜0.01), and 1.16, 1.54 and 1.51 times that of rats in the samecondition (P＜0.01). EPO expression levels of chronic groups of zokors in brain, liverand kidney are 2.31 (P＜0.01), 1.32 (P＜0.01) and 1.13 times (P＜0.05) that of normoxiagroup, and they are 1.61, 1.20 times (P＜0.01) and no significant difference comparedwith rats in the same condition separately.Expression level of EPO is relatively low in tissues of rats under normoxia.Levels of EPO in the brain, liver and kidney of acute hypxia group of rats is 3.38,2.86 and 3.19 times that of normoxia group (P＜0.01). Levels of EPO in the brain,liver and kidney of chronic hypxia group of rats is 1.57, 1.44 and 1.28 times that of normoxia group (P＜0.01).6. VEGF were broadly expressed in tissues of zokors under nomoxia, and itsexpression level in the brain, kidney and liver are 4.96, 6.85 and 10.83 times that ofrats (P＜0.01). There are no significant differences in the levels of VEGF in the threetissues of zokors between acute hypoxia group and normoxia group (P＞0.05). Levelsof VEGF in the brian, kidney of chronic hypoxia group are 1.20 and 1.08 times that ofnormoxia group (P＜0.01), and there are no significant differences in the liver betweenthese two groups (P＞0.05). VEGF is very important in vasculogenesis andangiogenesis. Its broad expression in tissues of zokors support higher density ofcapillary vessels. Thus the ability of tissues and cells to gain O₂ is approvedsignificantly. So zokors can live long time in hypoxia environment.Levels of VEGF are very low in rats under normoxia. Levels of VEGF in thebrain and kidney of acute hypxia group of rats is 1.48 (P＜0.05) and 1.74 (P＜0.01)times that of normoxia group, and there are no significant differences in the liverbetween these two groups (P＞0.05). Levels of VEGF in the brain, liver and kidney ofchronic hypxia group of rats is 4.49, 2.91 and 2.87 times that of normoxia group(P＜0.01).In conclusion, effects on the blood viscosity, RBC configuration and expressionof HIF-1a, EPO and VEGF are all different in zokors and rats. Changes of bloodviscosity of zokors are more advantageous than rats. Influence of hypoxia on the RBCconfiguration is very weakly. Expression of HIF-1a and VEGF are broad in the tissuesof zokors under normoxia, especially VEGF expressing at high level continuously,and there expression level are all higher than rats under three treatments. Expressionlevel of EPO is also higher than rats in these three groups. High expression of thesegenes correlate to hypoxia is the intrinsic factor of the hypoxia adaptation of zokors.