Sensitivity of the sodium efflux in single barnacle muscle fibers to the microinjection of aluminum.
A study has been made of the behavior of the Na efflux in single muscle fibers from the barnacle, Balanus nubilus, toward the microinjection of AlCl3. The effect of microinjecting AlCl3 is either biphasic with inhibition following transitory stimulation, or monophasic with inhibition occurring promptly and taking about 1 hr to reach a maximum. The magnitude of the inhibition is dose dependent and the minimally effective concentration is 10 mM. This is diluted by the myoplasm by a factor of roughly 100. Fibers injected with 1 M AlCl3 are found to be insensitive to 10(-4) M ouabain, whereas fibers injected with 0.5 M AlCl3 show a further fall in Na efflux, which is smaller than that seen in control fibers. The response of the ouabain-insensitive Na efflux to the injection of 0.5 M AlCl3 is biphasic: stimulation is followed by inhibition. The stimulatory phase is largely dependent on the presence of external Ca2+ and is reversed by the sudden omission of Ca2+ from the bathing medium. Fibers also injected with 0.5 M AlCl3 show a marked reduction in the response of the Na efflux to high external K. Injection of ATPMg before or after the injection of AlCl3 fails in most instances to abolish or reverse the inhibitory effect. By contrast, fibers preinjected with deferoxamine show little or no effect following the injection of AlCl3. However, external application of deferoxamine is ineffective.
Bittar
E E
EE
Department of Physiology, University of Wisconsin, Madison 53706.
Nwoga
J
J
Huang
Y P
YP
D000535:Aluminum / Q000008:administration & dosage / Q000494:pharmacology*; D000077410:Aluminum Chloride; D017607:Aluminum Compounds; D000818:Animals; D002712:Chlorides / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D066298:In Vitro Techniques; D008845:Microinjections; D009132:Muscles / Q000187:drug effects* / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D015222:Sodium Channels / Q000187:drug effects* / Q000378:metabolism; D012979:Sodium Radioisotopes; D001468:Thoracica / Q000187:drug effects* / Q000378:metabolism
D017607:Aluminum Compounds; D002712:Chlorides; D015222:Sodium Channels; D012979:Sodium Radioisotopes; D000077410:Aluminum Chloride; D012964:Sodium; D000535:Aluminum