Costanzo J P, Lee R E
Department of Zoology, Miami University, Oxford, Ohio 45056.
Am J Physiol. 1991 Dec;261(6 Pt 2):R1346-50. doi: 10.1152/ajpregu.1991.261.6.R1346.
Erythrocytes from the freeze-tolerant wood frog (Rana sylvatica) were subjected to in vitro tests of freeze tolerance, cryoprotection, and osmotic fragility. The responses of cells from frogs acclimated to 4 or 15 degrees C were similar. Erythrocytes that were frozen in saline hemolyzed at -4 degrees C or lower. The addition of high concentrations (150 and 1,500 mM) of glucose or glycerol, cryoprotectants produced naturally by freeze-tolerant frogs, significantly reduced cell injury at -8 degrees C, but concentrations of 1.5 or 15 mM were ineffective. Hemolysis was reduced by 94% with 1,500 mM glycerol and by 84% with 1,500 mM glucose; thus glycerol was the more effective cryoprotectant. Mean fragility values for frog erythrocytes incubated in hypertonic and hypotonic saline were 1,938 and 49 mosM, respectively. Survival in freeze tolerance and cryoprotection experiments was comparable for erythrocytes from frogs and humans, suggesting that these cells may respond similarly to freezing-related stresses. However, the breadth of osmotic tolerance, standardized for differences in isotonicity, was greater for frog erythrocytes than for human erythrocytes. Our data suggest that erythrocytes from R. sylvatica are adequately protected by glucose under natural conditions of freezing and thawing.
对耐冻林蛙（林蛙）的红细胞进行了耐冻性、冷冻保护和渗透脆性的体外测试。适应4摄氏度或15摄氏度环境的青蛙的细胞反应相似。在盐水中冷冻的红细胞在零下4摄氏度或更低温度下会溶血。添加高浓度（150和1500毫摩尔）的葡萄糖或甘油（耐冻青蛙自然产生的冷冻保护剂）可显著降低零下8摄氏度时的细胞损伤，但1.5或15毫摩尔的浓度无效。1500毫摩尔甘油可使溶血降低94%，1500毫摩尔葡萄糖可使溶血降低84%；因此甘油是更有效的冷冻保护剂。在高渗和低渗盐水中孵育的青蛙红细胞的平均脆性值分别为1938和49毫渗摩尔。青蛙和人类红细胞在耐冻性和冷冻保护实验中的存活率相当，这表明这些细胞对与冷冻相关的应激反应可能相似。然而，根据等渗性差异进行标准化后，青蛙红细胞的渗透耐受性范围比人类红细胞更大。我们的数据表明，在自然的冻融条件下，林蛙的红细胞受到葡萄糖的充分保护。
