Bittar E E, Huang Y P
Department of Physiology, University of Wisconsin, Madison 53706.
Biochim Biophys Acta. 1993 May 14;1148(1):123-6. doi: 10.1016/0005-2736(93)90168-y.
The object of the present study was to test the hypothesis that the pre-enrichment of single muscle fibers from the barnacle Balanus nubilus with inorganic phosphate may protect the basal Na efflux from the inhibitory effect of Al injection. This approach was adopted in the light of evidence that the preinjection of ATP fails to stop the Na efflux in unpoisoned fibers from falling following the injection of Al. The results of the experiments are as follows: (i) Preinjection of K2HPO4 into unpoisoned fibers reduces the magnitude of the inhibitory effect on the basal Na efflux of injected Al in a dose-dependent manner but fails to completely stop it from occurring. (ii) Injection of K2HPO4 following Al into unpoisoned fibers fails to arrest or reverse the inhibitory effect of injected Al. (iii) Injection of K2HPO4 in a concentration as high as 0.5 M is without effect on the course of the basal Na efflux. (iv) Injection of K2HPO4 into ouabain-poisoned fibers fails to stop Al from stimulating the ouabain-insensitive Na efflux. Injection of K2HPO4 following peak stimulation by injecting Al is also without effect. (v) Injection of K2HPO4 in a concentration as high as 0.5 M is without effect on the course of the ouabain-insensitive Na efflux. Collectively, the results obtained with unpoisoned 'hypersensitive' fibers are consistent with the view that a significant fraction of the injected inorganic phosphate binds Al3+, and hence protects the basal Na efflux from the untoward action of Al3+.
用无机磷酸盐对藤壶巨藤壶的单根肌纤维进行预富集，可能会保护基础钠外流免受铝注射的抑制作用。鉴于有证据表明，预先注射ATP无法阻止未中毒纤维中钠外流在注射铝后下降，因此采用了这种方法。实验结果如下：(i) 向未中毒纤维预先注射K2HPO4，以剂量依赖的方式降低了注射铝对基础钠外流的抑制作用幅度，但未能完全阻止其发生。(ii) 在铝注射后向未中毒纤维注射K2HPO4，未能阻止或逆转注射铝的抑制作用。(iii) 注射浓度高达0.5 M的K2HPO4对基础钠外流过程没有影响。(iv) 向哇巴因中毒的纤维注射K2HPO4，未能阻止铝刺激哇巴因不敏感的钠外流。在注射铝达到峰值刺激后注射K2HPO4也没有效果。(v) 注射浓度高达0.5 M的K2HPO4对哇巴因不敏感的钠外流过程没有影响。总体而言，用未中毒的“超敏”纤维获得的结果与以下观点一致，即注入的无机磷酸盐中有很大一部分与Al3+结合，从而保护基础钠外流免受Al3+的不良作用。
