在无HCO₃⁻情况下降低pH对牛蛙胃窦异常和正常电位反应的影响
Effect of reduced pH in absence of HCO3(-) on anomalous and normal potential responses in bullfrog antrum.
作者信息
Schwartz M, Carrasquer G, Rehm W S
出版信息
Biochim Biophys Acta. 1984 Jun 27;773(2):189-96. doi: 10.1016/0005-2736(84)90082-8.
Effect of changing [K+], [Na+] and [Cl-] in nutrient solution on potential difference (PD) and resistance was studied in bullfrog antrum with and without nutrient HCO3(-) but with 95% O2/5% CO2 in both cases. In both cases, changing from 4 to 40 mM K+ gave about the same initial PD maximum (anomalous response) which was followed by a decrease below control level. Latter effect was much less with zero than with 25 mM HCO3(-). Changing from 102 to 8 mM Na+ gave initial normal PD response about the same in both cases. However, 10 min later the change in PD with zero HCO3(-) was insignificant but with 25 mM HCO3(-) the PD decreased (anomalous response of electrogenic NaCl symport). PD maxima due to K+ and Na+ were largely related to (Na+ + K+)-ATPase pump. Changes in nutrient Cl- from 81 to 8.1 mM gave only a decrease in PD (normal response). Initial PD increases are explained by relative increases in resistance of simple conductance pathways and of parallel pathways of (Na+ + K+)-ATPase pump and Na+/Cl- symport. Removal of HCO3(-) and concurrent reduction of pH modify resistance of these pathways.
在有和没有营养液 HCO₃⁻的情况下，研究了营养液中[K⁺]、[Na⁺]和[Cl⁻]的变化对牛蛙胃窦电位差（PD）和电阻的影响，两种情况下均通入 95% O₂/5% CO₂。在这两种情况下，将 K⁺浓度从 4 mM 变为 40 mM 时，最初的 PD 最大值大致相同（反常反应），随后降至对照水平以下。与 25 mM HCO₃⁻相比，零 HCO₃⁻时后一种效应要小得多。将 Na⁺浓度从 102 mM 变为 8 mM 时，两种情况下最初的正常 PD 反应大致相同。然而，10 分钟后，零 HCO₃⁻时 PD 的变化不显著，但 25 mM HCO₃⁻时 PD 降低（电中性 NaCl 同向转运体的反常反应）。由 K⁺和 Na⁺引起的 PD 最大值在很大程度上与（Na⁺ + K⁺）-ATP 酶泵有关。营养液中 Cl⁻浓度从 81 mM 变为 8.1 mM 时，仅使 PD 降低（正常反应）。最初的 PD 增加可以通过简单传导途径以及（Na⁺ + K⁺）-ATP 酶泵和 Na⁺/Cl⁻同向转运体的平行途径电阻的相对增加来解释。去除 HCO₃⁻并同时降低 pH 会改变这些途径的电阻。
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