湾鳄血液的呼吸特性。

Respiratory properties of the blood of Crocodylus porosus.

作者信息

Grigg G C, Cairncross M

出版信息

Respir Physiol. 1980 Sep;41(3):367-80. doi: 10.1016/0034-5687(80)90083-3.

Abstract

The blood of Crocodylus porosus has a high oxygen capacity (5.5 mmol . 1-1 at hematocrit = 28%). The shape of the oxygen equilibrium curve of the blood is described by 'n' = 2.7 in the physiological range of PCO2, and its oxygen affinity is described by the equation: log10P50 = 0.4163 + 0.0200 T degrees C + 0.3763 log10PCO2. Thus, the blood has a low oxygen affinity which is strongly sensitive to both temperature and PCO2. There is a high buffering capacity, 37 mmol . (1 . pH)-1, and a large Haldane effect, 0.93 mmol CO2 (mmol Hb)-1. The fixed-acid Bohr effect seems to be much reduced in comparison to the CO2-specific Bohr effect. We discuss the possibility that low levels of red cell organic phosphate may be an adaptive strategy to desensitise P50 to changes in plasma pH. The significance of the blood respiratory properties is discussed in terms of the life style of C. porosus, particularly in relation to ectothermy and diving.

摘要

湾鳄的血液具有较高的氧容量（血细胞比容为28%时为5.5 mmol·L⁻¹）。在生理范围内的PCO₂条件下，血液的氧平衡曲线形状用“n”=2.7来描述，其氧亲和力由以下方程表示：log₁₀P₅₀ = 0.4163 + 0.0200×T（℃）+ 0.3763 log₁₀PCO₂。因此，血液具有较低的氧亲和力，且对温度和PCO₂都非常敏感。其具有较高的缓冲能力，为37 mmol·（L·pH⁻¹），以及较大的哈代效应，为0.93 mmol CO₂（mmol Hb⁻¹）。与CO₂特异性玻尔效应相比，固定酸玻尔效应似乎大大降低。我们讨论了红细胞有机磷酸盐水平较低可能是一种使P50对血浆pH变化不敏感的适应性策略的可能性。根据湾鳄的生活方式，特别是与变温性和潜水的关系，讨论了血液呼吸特性的意义。