Effect of veratrine on the 24Na exchange of frog sartorius

T. Kovacs, B. Szabo, E. Varga

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Abstract

Investigations of the effect of 0.1 mM of veratrine on the 24Na exchange of frog sartorius has led to the following results. Muscles exposed to veratrine during 24Na loading subsequently exchanged sodium more rapidly than controls. The enhancement of Na exchange found when muscles were treated with veratrine during 24Na loading differs from the increased rate of 24Na efflux observed when veratrine was applied only during a steady phase of 24Na efflux determination. The latter effect is Na dependent, while the former can be observed using either normal or Na free solutions. The effect of veratrine applied during efflux measurement also differs from the effect on 24Na loading in that it is merely transient, while the increased efflux from muscles loaded in the presence of veratrine persists over several hours of subsequent efflux. Since muscles depolarized by exposure to veratrine and repolarized on return to veratrine free, choline Ringer, the sustained effect of veratrine on 24Na efflux is not dependent upon a maintained depolarized state of the muscle membrane. The rate of loss of 24Na, from muscles which were 24Na loaded in the presence of veratrine, was increased even when the Na pump and exchange diffusion were inhibited by use of K free choline Ringer's solution and cooling, respectively. The Na influx enhancing effect of veratrine described by the authors earlier occurs also in Ringer's solutions of low (20 and 2 mM) Na concentration. These results suggests that the extra sodium taken up by muscles in the presence of veratrine is intracellularly located differently to the sodium exchanged in control muscles.

Original languageEnglish
Pages (from-to)167-178
Number of pages12
JournalActa Physiologica Academiae Scientiarum Hungaricae
Volume43
Issue number2
Publication statusPublished - 1973

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Veratrine
Anura
Muscles
Sodium
Choline

ASJC Scopus subject areas

  • Physiology

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Effect of veratrine on the 24Na exchange of frog sartorius. / Kovacs, T.; Szabo, B.; Varga, E.

In: Acta Physiologica Academiae Scientiarum Hungaricae, Vol. 43, No. 2, 1973, p. 167-178.

Research output: Contribution to journalArticle

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N2 - Investigations of the effect of 0.1 mM of veratrine on the 24Na exchange of frog sartorius has led to the following results. Muscles exposed to veratrine during 24Na loading subsequently exchanged sodium more rapidly than controls. The enhancement of Na exchange found when muscles were treated with veratrine during 24Na loading differs from the increased rate of 24Na efflux observed when veratrine was applied only during a steady phase of 24Na efflux determination. The latter effect is Na dependent, while the former can be observed using either normal or Na free solutions. The effect of veratrine applied during efflux measurement also differs from the effect on 24Na loading in that it is merely transient, while the increased efflux from muscles loaded in the presence of veratrine persists over several hours of subsequent efflux. Since muscles depolarized by exposure to veratrine and repolarized on return to veratrine free, choline Ringer, the sustained effect of veratrine on 24Na efflux is not dependent upon a maintained depolarized state of the muscle membrane. The rate of loss of 24Na, from muscles which were 24Na loaded in the presence of veratrine, was increased even when the Na pump and exchange diffusion were inhibited by use of K free choline Ringer's solution and cooling, respectively. The Na influx enhancing effect of veratrine described by the authors earlier occurs also in Ringer's solutions of low (20 and 2 mM) Na concentration. These results suggests that the extra sodium taken up by muscles in the presence of veratrine is intracellularly located differently to the sodium exchanged in control muscles.

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