Kamm K E, Casteels R
Pflugers Arch. 1979 Jul;381(1):63-9. doi: 10.1007/BF00582333.
Contraction strength was measured in ear artery and aorta of the rabbit and coronary artery of the pig during replacement of chloride with anions of the lyotrophic series. Contractions induced by depolarization with elevated external potassium were potentiated in the presence of foreign anions, while those induced by noradrenaline were affected only at higher concentrations of the drug. Drug induced contractions in calcium-free solutions were not affected by the anions. In the presence of nitrate and excess K the change of membrane potential per tenfold change in (K)o was 56mV in chloride and 50 mV in nitrate solution. Enhancement of contraction strength by nitrate was not associated with alterations in membrane potential. Stimulation of aorta with 29.5 mM K resulted in a larger net uptake of 45Ca in nitrate than in chloride. K-stimulated 45Ca efflux was greater in the ear artery in NO3 solution than Cl solution while 45Ca efflux induced by noradrenaline was not effected by anion replacement. These results suggest that in these arteries anions potentiate contraction by enhancing the influx of external calcium, and do not modify the release of internal stores of calcium.
在以促溶剂系列阴离子替代氯离子的过程中，测量了兔耳动脉、主动脉以及猪冠状动脉的收缩强度。在存在外来阴离子的情况下，由细胞外钾浓度升高引起的去极化所诱导的收缩增强，而由去甲肾上腺素诱导的收缩仅在较高药物浓度时受到影响。在无钙溶液中药物诱导的收缩不受阴离子影响。在存在硝酸盐和过量钾的情况下，（钾离子）细胞外浓度每增加10倍时，氯离子溶液中的膜电位变化为56mV，硝酸盐溶液中为50mV。硝酸盐对收缩强度的增强与膜电位的改变无关。用29.5mM钾刺激主动脉时，硝酸盐溶液中45钙的净摄取量比氯离子溶液中更大。在硝酸盐溶液中，钾刺激引起的45钙外流在耳动脉中比在氯离子溶液中更大，而去甲肾上腺素诱导的45钙外流不受阴离子替代的影响。这些结果表明，在这些动脉中，阴离子通过增强细胞外钙的内流来增强收缩，而不改变细胞内钙储备的释放。
