Bridges C R, Scheid P
Respir Physiol. 1982 May;48(2):183-97. doi: 10.1016/0034-5687(82)90079-2.
To assess the extent of CO2 storage and the changes in the acid-base status that occur during intermittent CO2 excretion in insects, total CO2 content and pH were measured in whole body homogenates (= tissue homogenates) of Hyalophora cecropia pupae at various levels of Pco2 at 20 degrees C. The CO2 dissociation curve, i.e. plot of total CO2 content in tissue homogenates against Pco2 was nearly linear in the Pco2 range from 15 to 50 Torr, the mean slope being 0.138 mM . Torr-1. This value, which constitutes the effective CO2 solubility, was nearly three times the physical solubility in the tissue homogenate which averaged 0.053 mM . Torr-1. Plots of bicarbonate concentration in whole body tissue water against pH yielded an average buffer value of 75 mmol . pH-1 per kg tissue water. The high buffer value results in a small pH change, about 0.04 units, when Pco2 varies between 20 and 45 Torr in the respiratory cycle. The absolute value of mean tissue pH at Pco2 = 30 Torr predicted from the buffer line, 6.57, agrees well with direct measurement in hemolymph samples.
为了评估昆虫间歇性排出二氧化碳期间二氧化碳的储存程度以及酸碱状态的变化，在20℃下，于不同二氧化碳分压水平下，对天蚕蛹的全身匀浆（即组织匀浆）中的总二氧化碳含量和pH值进行了测量。在15至50托的二氧化碳分压范围内，组织匀浆中总二氧化碳含量相对于二氧化碳分压的曲线，即二氧化碳解离曲线几乎呈线性，平均斜率为0.138毫摩尔·托⁻¹。该值构成有效二氧化碳溶解度，几乎是组织匀浆中物理溶解度（平均为0.053毫摩尔·托⁻¹）的三倍。全身组织水中碳酸氢盐浓度相对于pH值的曲线得出平均缓冲值为每千克组织水75毫摩尔·pH⁻¹。高缓冲值导致在呼吸周期中，当二氧化碳分压在20至45托之间变化时，pH值变化很小，约为0.04个单位。根据缓冲线预测，在二氧化碳分压 = 30托时平均组织pH值的绝对值为6.57，与血淋巴样本中的直接测量结果吻合良好。
