Schwartz M, Carrasquer G, Rehm W S
Biochim Biophys Acta. 1985 Jun 27;816(2):251-7. doi: 10.1016/0005-2736(85)90492-4.
The effect of changing the nutrient HCO3- concentration on potential difference (PD) and resistance in bullfrog antrum bathing in CI- media was determined. Changes in HCO3- concentration were from 25 mM to several lower concentrations and back to 25 mM. A plot of /delta PD/ versus log [HCO3-] gave a linear relation for changes of HCO3- concentration from 25 down to 3.1 mM and back to 25 mM but deviated to some extent for changes to 1.6 mM. In these experiments, changes from higher to lower HCO3- concentrations gave a less rapid initial PD response than those in the reverse direction. This result eliminated H+ conductance pathways as being predominant. Experiments were done in which in the first part changes were made in nutrient solution from 5 percent CO2 and 25 mM HCO3- to 0.6 percent CO2 and 3 mM HCO3- and in the second part the same changes with a simultaneous changes of secretory solution from 5 percent to 10 percent CO2. The magnitude of PD decrease was greater by 4.5 mV in the second part. This result indicated that HCO3- conductance pathways rather than OH- conductance pathways are predominated . There was no evidence of HCO3-, OH-, and H+ conductance pathways in secretory membranes.
测定了在氯化物介质中浸泡的牛蛙胃窦中，改变营养物中HCO₃⁻浓度对电位差（PD）和电阻的影响。HCO₃⁻浓度从25 mM变化到几个较低浓度，然后再回到25 mM。绘制ΔPD与log[HCO₃⁻]的关系图，结果显示，当HCO₃⁻浓度从25 mM降至3.1 mM然后再回到25 mM时呈线性关系，但当HCO₃⁻浓度变为1.6 mM时，关系图在一定程度上出现偏差。在这些实验中，HCO₃⁻浓度从高到低变化时，初始PD反应比反向变化时更缓慢。这一结果排除了H⁺传导途径占主导地位的可能性。实验分为两部分进行，第一部分将营养液中的CO₂从5%和HCO₃⁻从25 mM变为0.6% CO₂和3 mM HCO₃⁻，第二部分进行相同的变化，同时将分泌液中的CO₂从5%变为10%。第二部分中PD降低的幅度更大，为4.5 mV。这一结果表明，占主导地位的是HCO₃⁻传导途径而非OH⁻传导途径。在分泌膜中没有证据表明存在HCO₃⁻、OH⁻和H⁺传导途径。
