A Comparative Study On The Oxygen Transport Function Of Bufo Gargarizans Populations At Different Altitudes

Bufo gargarizans belongs to Anura,Bufonidae,and is widely distributed in China.In order to investigate whether there is a physiological and functional adaptation of high-altitude living B.gargarizans in the blood oxygen transport,we selected the Zoige population?3450 m?and the Chengdu population?500 m?.And we compared the hematological parameters and the function of hemoglobin of two populations.We measured the morphology,number,and hematocrit of red blood cells.The oxygen equilibrium curves and P₅₀ of both populations were determined by the"gas diffusion chamber"method.The O₂ equilibrium curve and P₅₀ of purified hemoglobin from both populations were also measured at different temperatures,different pH values,and whether there is an allosteric regulatory factors adenosine triphosphate?ATP?and/or Cl^-.The Bohr effect of hemoglobin and the sensitivity to temperature,ATP and chloride ion of two populations were compared.In addition,the ratio of heart weight to body mass and pulmonary weight to body mass was examined as well.The results showed that high-altitude toads had higher heart weight to body mass?HW/BM?and lower pulmonary weight to body mass?PW/BM?.In the hematological parameters,the high population possessed larger red blood cell count,higher Hb concentration and hematocrit.The long axis of red blood cells was shorter and the volume of red blood cells was smaller in high-altitude population.The affinity to oxygen of whole blood in high-altitude population was higher than low-altitude one.The blood oxygen affinity analysis of purified hemoglobin showed that the hemoglobin of the high-altitude B.gargarizans population had higher intrinsic oxygen affinity.The oxygen affinities of Hb under different temperatures,different pH values and the presence or absence of allosteric factors in high-altitude population were all higher than in low-altitude population.The Bohr Effect of hemoglobin of high-altitude population was higher at 10?C but lower at 20?C than that if low-altitude population.At the presence of both allosteric factors ATP and Cl^-the hemoglobin of high-altitude showed stronger Bohr Effect and high sensitivity to temperature.These characteristics are beneficial to the oxygen transport for Bufo gargarizans in hypoxic environment.Based on the findings mentioned above we suggest that the populations of Bufo gargarizans at high and low altitudes possess the features for them to adapt to their own environments and the toads at high altitude have stronger ability for oxygen transport.