Avenet P, Lignon J M
J Physiol. 1985 Jun;363:377-401. doi: 10.1113/jphysiol.1985.sp015717.
The cuticle of the gill lamina of the crayfish Astacus leptodactylus (E), mechanically isolated, was mounted in an Ussing chamber and examined for its electrical properties. The cuticle of the gill lamina obtained from exuviae had similar properties. When perfused with artificial fresh water (AFW) outside and Van Harreveld solution (VH) inside, the transcuticular potential Voi was negative with respect to the inside, and close to the equilibrium potential for Cl- (ECl-). CH3COO-, HCO3-, SO4(2-) and cations (Na+, K+, Ca2+, Mg2+ and NH4+) behaved as impermeant ions with respect to Cl-. A decrease of pH (brought about with CO2) from 8.5 to 6.0 in AFW, VH or both had no effect on the potential. The cuticle area specific conductance was 20-30 mS/cm2 when superfused with AFW outside and VH inside. The conductance decreased linearly with log [Cl-] when Cl- was replaced by CH3COO-. Rectification was obvious when internal Cl- was reduced to 5 mmol/l. The Cl- selectivity of the cuticle could also be demonstrated in perfusing the cuticle with a single salt (NaCl, KCl, CaCl2, MgCl2 or LaCl3) and in diluting that salt on one side of the preparation or in replacing Cl- by CH3COO-, SO4(2-) and HCO3-. The potential changed almost linearly with log [Cl-] and was close to ECl-. The inner face of the cuticle was found to be slightly less selective than the outer face. The relative permeabilities were calculated to be: PCl- = 1, PNa+ = 0.001, PHCO3- = 0.0006, PCH3COO- = 0.0002. The dilution of a Cl- -free salt resulted in a cationic potential. The relative permeabilities of cations (NH4+, K+, Na+, Ca2+ and Mg2+) were found to range within a factor 2. The permeability of the cuticle to HCO3-, CH3COO- and SO4(2-) was 2-5 times lower. The cuticle conductance was linearly related to the activity of the salt perfusing the two sides of the preparation at equal concentrations. The molar area specific conductance to chloride salts was 14 (mS/cm2)/(mmol/l). That of Cl- -free salts ranged from 1 to 20 (microS/cm2)/(mmol/l) depending on the salt used. It was deduced that PCl- is 2 X 10(-3) cm/s and that all the other ions tested have permeabilities of 10(-7)-10(-6) cm/s. With large intensity current pulses the cuticle exhibited rectifying properties and an asymmetrical behaviour. Increasing the pH of the perfusing solution reduced the transcuticular potential established with a Cl- gradient.(ABSTRACT TRUNCATED AT 400 WORDS)
对细指螯虾（Astacus leptodactylus (E)）鳃小片的角质层进行机械分离，将其置于尤斯灌流小室中，检测其电学性质。从蜕壳获取的鳃小片角质层具有相似的性质。当外部灌注人工淡水（AFW），内部灌注范哈勒维尔德溶液（VH）时，跨角质层电位Voi相对于内部为负，且接近氯离子平衡电位（ECl-）。CH3COO-、HCO3-、SO4(2-)和阳离子（Na+、K+、Ca2+、Mg2+和NH4+）相对于Cl-表现为非渗透性离子。在AFW、VH或两者中，将pH值（通过CO2实现）从8.5降至6.0对电位无影响。当外部用AFW灌注、内部用VH灌注时，角质层的面积比电导率为20 - 30 mS/cm2。当用CH3COO-替代Cl-时，电导率随log [Cl-]呈线性下降。当内部Cl-降至5 mmol/l时，整流现象明显。角质层对Cl-的选择性也可通过用单一盐（NaCl、KCl、CaCl2、MgCl2或LaCl3）灌注角质层、在标本一侧稀释该盐或用CH3COO-、SO4(2-)和HCO3-替代Cl-来证明。电位几乎随log [Cl-]呈线性变化，且接近ECl-。发现角质层内表面的选择性略低于外表面。计算得到的相对渗透率为：PCl- = 1，PNa+ = 0.001，PHCO3- = 0.0006，PCH3COO- = 0.0002。不含Cl-的盐稀释会产生阳离子电位。发现阳离子（NH4+、K+、Na+、Ca2+和Mg2+）的相对渗透率在2倍范围内。角质层对HCO3-、CH3COO-和SO4(2-)的渗透率低2 - 5倍。角质层电导率与以相同浓度灌注标本两侧的盐的活性呈线性相关。对氯化物盐的摩尔面积比电导率为14 (mS/cm2)/(mmol/l)。不含Cl-的盐的摩尔面积比电导率根据所用盐的不同在1至20 (μS/cm2)/(mmol/l)范围内。推断PCl-为2×10(-3) cm/s，所有其他测试离子的渗透率为10(-7) - 10(-6) cm/s。施加高强度电流脉冲时，角质层表现出整流特性和不对称行为。提高灌注溶液的pH值会降低由Cl-梯度建立的跨角质层电位。（摘要截取自400字）
