Concerning stimulation by injected fluoroaluminate of the sodium efflux in barnacle muscle fibers.
Single barnacle muscle fibers from Balanus nubilus were used primarily to examine the validity of two ideas: first, that the injection of KF stimulates the ouabain-insensitive Na+ efflux, and that this action is potentiated by adding AlCl3 (Al) in a low concentration to the solution of KF prior to injection. And second, that the injection of a KF-AlCl3 solution into ouabain-poisoned, K(+/-)-depolarized fibers elicits a stimulatory response resembling that obtained by injecting GTP. The results of this study are as follows: injection of 0.5 M KF into unpoisoned fibers causes a sustained rise in the resting Na+ efflux. However, injection of a 0.5 M KF, 10(-3) M AlCl3 solution leads to a reduced rather than an augmented response. Whereas injection of 0.5 M KF into ouabain-poisoned fibers elicits a marked stimulatory response, the injection of 0.5 M KF, 10(-3) M AlCl3 reduces the remaining Na+ efflux. Injection of KF-AlCl3 in equimolar concentrations, e.g., 0.25 M, elicits a response that is significantly larger than that obtained by injecting 0.25 M KF. A dose-response curve indicates that a 0.2 M solution of fluoroaluminate probably represents an optimal concentration. Injection of 0.3 M KF following peak stimulation by injecting 0.3 M AlCl3 completely reverses this response to Al. In sharp contrast, injection of a 0.3 M KF, 0.3 M AlCl3 mixture following peak stimulation by injecting 0.3 M AlCl3 is ineffective. Injection of KF into ouabain-poisoned, K+ depolarized fibers does not always cause sustained stimulation of the remaining Na+ efflux.(ABSTRACT TRUNCATED AT 250 WORDS)
Bittar
E E
EE
Department of Physiology, University of Wisconsin, Madison 53706.
Huang
Y P
YP
D000262:Adenylyl Cyclases / Q000378:metabolism; D000535:Aluminum / Q000494:pharmacology*; D000077410:Aluminum Chloride; D017607:Aluminum Compounds / Q000494:pharmacology; D000818:Animals; D002712:Chlorides / Q000494:pharmacology; D004357:Drug Synergism; D005089:Exocytosis; D005461:Fluorine / Q000494:pharmacology*; D006160:Guanosine Triphosphate / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism*; D013268:Stimulation, Chemical; D001468:Thoracica / Q000187:drug effects*
D017607:Aluminum Compounds; D002712:Chlorides; C053629:fluoroaluminum; D005461:Fluorine; D000077410:Aluminum Chloride; D006160:Guanosine Triphosphate; D012964:Sodium; D000535:Aluminum; D000262:Adenylyl Cyclases