| The gansu zokor is one of the blind subterranean mole rats that spend their life solely underground in seals burrows.Belong to the genus Myospalax family of Cricetidae,they are one of the specialized species in Loess plateau.Because of the long time of underground life,they developed a series of structures and physiological mechanisms to adapt to hypoxia-hypercapnia and dark environment.Thus,they are good materials for hypoxia-hypercapnia research. The oxygen affinity and acid-base buffering capacity of gansu zokor in hypoxia-hypercapnia had not been reported so far.In order to disscuss its hematological adaptation mechanisms,the blood gas analysis was carried out under 20.5%,15%,10%,5% oxygen and 0%,5%,10% carbon dioxide concentration,whichi maybe provide some information for underground adaptation mechanisms.The results were as follows:1.Under normoxic conditions, the hemoglobin concentrationand oxygen capacity of gansu zokor were 13.27±1.03g/dL and 17.78±1.54 ml/100ml, within the range of values reported for other subterranean rodents. While,hematocrit values(39.00±3.33%)were lower than that of the conspecific. Previous studies indicated that the mean corpuscular volume(MCV) and mean corpuscular hemoglobin concentration(MCHC) in blood of gansu zokors were significantly lower and higher than SD rats.Low HCT and MCV coupled with high MCHC meaned reduced blood viscosity and increased RBC surfaces to avoid blood viscosity,reduce resistance of blood circulation and cardiac stress,thus elevated the ability to oxygen transportation and enhanced diffusion of oxygen when blood gas exchanged in the lungs. In conclusion, the most appropriate mechanism for gansu zokor to adapt underground life maybe that a high hemoglobin-oxygen affinity with improvement to structure and function of Hb in gene expression level, not increased Hb and HCT concentrations.2. Under normoxic conditions, the oxygen partial pressure(84.33mmHg)and oxygen saturation(97.67%)in artery blood of gansu zokor were little higher than that of plateau zokor(Pa02:81.25 mmHg, SaO2:94.47%). P50 value was within reported range(21.2-33.6mmHg)of subterranean rodents,similar to those for H.glaber(23.3mmHg)and Talpa europaea(21.4mmHg),however, lower than that of similar sized Spalax ehrenbergi(P50:29.5mmHg). The P50 values for whole blood equilibrated in the presence of 0%,5% and 10% CO2 were 20.34mmHg(pH7.69),23.31 mmHg(pH7.50),30.18 mmHg(pH7.36) at 37℃. All results above were constructed three sigmoid oxygen dissociation curves(ODC) that accompanied with flat upsides and steep downsides. The upper part of 10% CO2 was almost coincided with 5%,suggested little effects on SaO2 that exposed to high concentration of CO2.However, it largely influenced SaO2 and ODCs in their lower parts that deviated obviously. We inferred that gansu zokor had a strong hemoglobin-oxygen affinity in lungs,and the blood of gansu zokor was sensitive to CO2,which responsed to high concentration of CO2 through the shift of ODCs to supply adequate oxygen to tissues.3.Under different O2 and CO2 contents, blood PaO2 and SaO2 of gansu zokor were changed as follows:Coupled with O2 content reduced to 10% and 5%, PaO2 values were reduced significantly(0.010.05).It suggested that the impact of O2 and CO2 content on blood PaO2 was significantly higher than SaO2,and the significant and extreme significant differences in PaO2 and SaO2 were only displayed under hypoxia conditions(10% and 5%O2), revealed that 5% O2 may be close to the critical hypoxia value of gansu zokor.Above 5% O2The hemoglobin had a high oxygen affinity to abtain oxygen, and it was opposite while below 5% O2.4.Under different O2 and CO2 contents, blood acid-base indicators of gansu zokor were changed as follows:Coupled with O2 content reduced,only PaCO2 values were significantly increased(0.010.05).It implied a little effect of O2 content on blood acid-base indicators, the CO2 content that affected blood acid-base indicators,which consistent with theory basis. Coupled with CO2 content increased, the PaCO2,HCO3,TCO2 values were increased significantly(0.01 |
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