Cooper K, Gates P, Rae J L, Dewey J
Department of Physiology, Mayo Foundation, Rochester, Minnesota 55905.
J Membr Biol. 1990 Sep;117(3):285-98. doi: 10.1007/BF01868458.
The lens epithelial K+ conductance plays a key role in maintaining the lens ionic steady state. The specific channels responsible for this conductance are unknown. We used cultured lens epithelia and patch-clamp technology to address this problem. Human lens epithelial explants were cultured and after 1-4 passages were dissociated and used in this study. The cells from which we measured had a mean diameter of 31 +/- 1 microns (SEM, n = 26). The resting voltage was -19 +/- 4 mV (SEM, n = 10) and the input resistance was 2.5 +/- 0.5 G omega (SEM, n = 17) at -60 mV. Two currents were prominent in whole-cell recordings. An outwardly rectifying current was seen in nearly every cell. The magnitude of this current was a function of K+ concentration and was blocked by 3 mM tetraethylammonium. The instantaneous current-voltage relationship was linear in symmetric K+, implying that the outward rectification was due to gating. The current showed complex activation and inactivation kinetics. The second current seen was a transient inward current. This current had kinetics very similar to the traditional Na+ current of excitable cells and was blocked by 0.1 microM tetrodotoxin. In single-channel recordings, a 150-pS K+ channel and a 35-pS nonselective cation channel were seen but neither account for the macroscopic currents measured.
晶状体上皮细胞的钾离子电导在维持晶状体离子稳态中起关键作用。负责这种电导的具体通道尚不清楚。我们利用培养的晶状体上皮细胞和膜片钳技术来解决这个问题。人晶状体上皮外植体进行培养，传代1 - 4次后解离并用于本研究。我们测量的细胞平均直径为31±1微米（标准误，n = 26）。在-60 mV时，静息电压为-19±4 mV（标准误，n = 10），输入电阻为2.
