Local superfusion modifies the inward rectifying potassium conductance of isolated retinal horizontal cells.
Local superfusion modifies the inward rectifying potassium conductance of isolated retinal horizontal cells.
复制标题
局部灌注改变了孤立的视网膜水平细胞的向内整流钾电导。
DOI：
10.1152/jn.1988.60.4.1322
复制
发表时间：
1988
影响因子：
2.5
通讯作者：
Dowling,JE
中科院分区：
文献类型：
--
作者：
Perlman,I;Knapp,AG;Dowling,JE
1.水平细胞酶和机械解离的白色鲈鱼（Roccus americana）视网膜和电压钳使用贴片电极。稳态电流-电压（I-V）关系的孤立的水平细胞，通过改变膜电位在一个斜坡的方式。2.在正常林格液中，细胞的I-V曲线在负膜电位时电导增加。该电导在K+平衡电位附近激活，没有明显的逆转电位，通过提高细胞外K+浓度而增强，并且被外部Cs+抑制。这些属性确定的电导向内（异常）整流器。3.用不含药物的林格氏液连续灌流细胞局部环境，降低了内向整流电流的幅度，并将其激活点转移到更负的电位。这种效应在大约30 s内发展，只要继续灌注就持续，并且在停止灌注后可逆。4.将无药物的林格氏溶液压力喷射到浸泡在相同溶液中的细胞上，也降低了内向整流电流的幅度，尽管这种作用比灌流所产生的作用更迅速、更短暂。当细胞同时灌注林格氏液时，压力喷射几乎没有影响，这表明内向整流器的共同作用模式。5.在没有灌流的情况下，含有200 μ M L-谷氨酸的林格氏液的压力喷射对膜电导有双相作用。在高于-60 mV的电位下，谷氨酸引起电导增加，逆转电位接近+10 mV。在低于-60 mV的电位下，谷氨酸引起电导降低，其逆转电位无法可靠地确定。后一种效应类似于单独应用林格氏液对内向整流器的抑制，这表明它可能代表压力喷射的伪影，而不是谷氨酸的直接效应。6.在支持这种解释，我们发现，压力喷射谷氨酸在外部Cs+的存在下（它阻止了内向整流器）或在局部灌注林格（防止衰减的内向整流器的压力喷射）没有引起电导下降在负电位。在这些条件下，谷氨酸主要引起电导增加，逆转电位接近+10 mV。（400字处截断摘要）
1. Horizontal cells were enzymatically and mechanically dissociated from the white perch (Roccus americana) retina and voltage clamped using patch electrodes. Steady-state current-voltage (I-V) relationships of solitary horizontal cells were determined by changing the membrane potential in a rampwise fashion. 2. The I-V curve of cells bathed in normal Ringer solution exhibited a large conductance increase at negative membrane potentials. This conductance activated near the K+ equilibrium potential, had no clear reversal potential, was enhanced by raising the extracellular concentration of K+, and was suppressed by external Cs+. These properties identify the conductance as the inward (anomalous) rectifier. 3. Continuous superfusion of the cells' local environment with drug-free Ringer reduced the magnitude of the inward rectifier current and shifted its activation point to more negative potentials. This effect developed over approximately 30 s, lasted as long as superfusion continued and was reversible upon cessation of superfusion. 4. Pressure ejection of drug-free Ringer solution onto cells bathed in the identical solution also reduced the magnitude of the inward rectifier current, although the effects were more rapid and more transient than those exerted by superfusion. Pressure ejection had little effect when cells were simultaneously superfused with Ringer, suggesting a common mode of action on the inward rectifier. 5. In the absence of superfusion, pressure ejection of Ringer containing 200 microM L-glutamate had a biphasic effect on membrane conductance. At potentials above -60 mV, glutamate caused a conductance increase with a reversal potential near +10 mV. At potentials below -60 mV, glutamate caused a conductance decrease whose reversal potential could not reliably be determined. The latter effect was similar to the suppression of the inward rectifier by application of Ringer alone, suggesting that it may represent an artifact of pressure ejection rather than a direct effect of glutamate. 6. In support of this interpretation, we found that pressure ejection of glutamate in the presence of external Cs+ (which blocks the inward rectifier) or during local superfusion with Ringer (which prevents attenuation of the inward rectifier by pressure ejection) did not cause a conductance decrease at negative potentials. Under these conditions, glutamate caused primarily a conductance increase with a reversal potential near +10 mV.(ABSTRACT TRUNCATED AT 400 WORDS)