E. Bittar

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Experiments show that the resting ouabain-insensitive sodium efflux in giant fibers from the barnacle Balanus nubilus is stimulated by external application of pentachlorophenol (PCP). This work has now been extended to include a study of muscle fibers preloaded with the Ca2+ indicator aequorin to determine whether PCP is able to increase light emission; and(More)
1. A further study has been made of the stimulatory action of proctolin on the ouabain-insensitive Na+ efflux in single muscle fibres from the barnacle, Balanus nubilus. 2. (i) Strontium (Sr2+) behaves as a substitute for external Ca2+. In this case, however, the response to proctolin fails to decay. (ii) Injection of Sr2+ stimulates the ouabain-insensitive(More)
Single barnacle muscle fibers from Balanus nubilus were used to study the effect of elevated external potassium concentration, [K]o, on Na efflux, membrane potential, and cyclic nucleotide levels. Elevation of [K]o causes a prompt, transient stimulation of the ouabain-insensitive Na efflux. The minimal effective concentrations is mM. The membrane potential(More)
This minireview discusses the use of single barnacle muscle fibers as a model system for studying hormonal actions. The response of barnacle muscle fibers to serotonin, proctolin, octopamine, aldosterone and insulin is described. Recent data relating to the actions of these hormones on other invertebrate and vertebrate preparations is touched upon. The use(More)
The response of the Na efflux in unpoisoned barnacle fibers to 10 mM theophylline is biphasic; i.e., inhibition is followed by stimulation. The stimulatory response is unaffected by ouabain. Fibers pretreated with ouabain show no transitory inhibition when 10 mM theophylline is applied, but show prompt stimulation the magnitude of which is comparable to(More)
The hypothesis that chloramine-T stimulates the basal Na+ efflux in barnacle fibers as the result of the entry of trigger Ca2+ into the myoplasm from the bathing medium was examined in this study. Two reasons for doing so can be given. One is that the oxidant is known to abolish inactivation in sodium and potassium channels. The other is that L-type Ca2+(More)
A study has been carried out using relatively intact mature muscle fibers from the barnacle Balanus nubilus to see whether D-Ins(1,4,5)P3 stimulates the ouabain-insensitive Na efflux following its microinjection and whether this is accompanied by a contraction of the fiber. Part of the impetus for a study of this type came from the on-going debate between(More)
A study has been made of the mechanism by which the injection of ATPNa2 stimulates the ouabain-insensitive Na efflux in fibers from the barnacle, Balanus nubilus. The results of this study are as follows: ATPNa2 is found to be a more potent effector of the Na efflux in unpoisoned fibers than ATPMg on an equimolar basis, but not more potent than ADPNa2. In(More)
1. A study has been made of the feasibility of monitoring myoplasmic ATPMg in single barnacle muscle fibres by microinjections DuPont luciferase-luciferin. 2. Injection of DuPont luciferase-luciferin into a cannulated fibre results almost immediately in light emission the intensity of which reaches a maximum within 2 sec and then decays in two phases, the(More)