Sensitivity of sodium efflux in barnacle muscle fibers to the microinjection of calcium chloride

Zusammenfassung Nachweis, dass der Auswärtsstrom von Natrium aus Muskelfasern der ArthropodenBalanus nubilus undBalanus aquila in künstlichem, kaliumfreiem Meerwasser durch Mikroinjektion von Kalziumchlorid aktiviert wird.

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Postdoctoral Fellow of the Wisconsin Heart Association.     

The influence of caffeine on the sodium efflux in barnacle muscle fibers

Zusammenfassung Nachweis, dass Coffein zunächst den Auswärtstrom von Na-Ionen aus Einzelfasern der Bernakelmuskeln verringert, ihn hernach aber zu steigern vermag.     

Sensitivity of the Na efflux in barnacle muscle fibres to the microinjection of troponin-C

Zusammenfassung Nachweis, dass eine Microinjektion von Troponin-C den Na-Ionen-Ausfluss aus Einzelfasern des Entenmuschel-Muskels steigert.     

Stimulation by caffeine of the calcium efflux in barnacle muscle fibers

Zusammenfassung Die Befunde ergeben, dass einzelne Muskelfasern der Entenmuschel durch Mikroinjektion mit⁴⁵Ca aufgeladen werden können. Eine Umspülung der Muskelfasern mit einer coffeinhaltigen Lösung bewirkt ein stärkeres Ausströmen des Calciums als eine Mikroinjektion des Coffeins in die Fasern direkt.     

Tris as a blocking agent of the proton-sensitive component of the sodium efflux in barnacle muscle fibers

Zusammenfassung Studien über den Natriumtransport in den Muskeln vonBalanus sp. haben bewiesen, dassTris den protonempfindlichen Anteil der Natrium-Pumpe verlangsamt und dasTris hauptsächlich an der Aussenseite des Sarkolemms aktiv ist.

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Acknowledgments. This work was supported in part by grants from the Wisconsin Heart Association, the Medical School Research Committee, the Graduate School Research Committee and the Office of Naval Research. Our thanks are due to Mr.Geoffrey Chambers for technical assistance. E.Y.T. is a Postdoctoral Fellow of the Wisconsin Heart Association. B.G.D. is a Visiting Scientist of the American Heart Association.     

Stimulation by aldosterone of the sodium efflux in barnacle muscle fibres

Zusammenfassung Es wurde gezeigt, dass die Natrium-Ausscheidung in der Muskelfaser von Entenmuskeln auf aldosteron reagiert.     

The influence of thymol on the sodium efflux in barnacle muscle fibres

Zusammenfassung Nachweis, dass Thymol sowie Coffein in der Barnakel-Muskelfaser eine primäre Hemmung mit nachfolgender Stimulierung des Natrium-Auswärtsstromes hervorruft.

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Acknowledgment. This work was supported in part by grants from the Wisconsin Heart Association, the Office of Naval Research, and the National Science Foundation.Donna Brown is a Post-doctoral Fellow of the Wisconsin Heart Association.     

Inhibition of the CO2-sensitive Na efflux in barnacle muscle fibers by micro-injection of ethacrynic acid

Zusammenfassung Es wird gezeigt, dass die Mikroinjektion von Äthacrynsäure [2,3-Dichloro-4(2-methylenbatyryl)-phenoxyacetsäure] in die isolierte Muskelfaser der Entenmuschel nur dann den Natriumausstrom herabsetzt, wenn die Badelösung vorher angesäuert wird.

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Thanks are due to Mr.Hans Östling for technical assistance during this investigation.     

The diffusion coefficient of sodium in barnacle muscle fibres

Zusammenfassung In Muskelfasern der Entenmuschel (Balanus nubilus undBalanus aquila) beträgt der Natrium Diffusions-Koeffizient 2,2×10^–6 cm²/sec.

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Acknowledgment. This work was supported in part by grants from the Office of Naval Research and the National Science Foundation.     

External strontium and contractility in single giant muscle fibers of the barnacle

Summary Isometric tension and membrane potential in response to electrical stimulation have been studied on single giant muscle fibers of the barnacle upon replacement of external calcium with strontium. Under these conditions, the membrane response showed after the normal peak depolarization, a plateau phase lasting 3–7 sec before repolarization took place, while the force of contraction showed a linear relation with external strontium concentration. A direct action of strontium ions on contractile proteins (namely troponin) can be ruled out in favor of a triggering action on the sarcoplasmic reticulum, which, in turn, leads to calcium release and development of tension.Acknowledgment. I wish to thank Dr C. C. ashley in whose laboratory the research reported in this paper was performed, and Mrs L. M. Castell for invaluable technical assistance. This work was supported by grant No. 106140/048104235 from Consiglio Nazionale delle Ricerche, Italy.     

Rp-diastereomer of adenosine cyclic 3',5'-phosphorothioate as an antagonist of the stimulatory action of cyclic AMP on the ouabain-insensitive Na efflux in single barnacle muscle fibers

Single muscle fibers of the barnacle Balanus nubilus have been used as a preparation to test the possibility that the Rp-diastereomer of adenosine cyclic 3',5'-phosphorothioate, which is the first available analog of cAMP that acts as an antagonist of cAMP, may reduce the magnitude of cAMP-mediated stimulation of the resting ouabain-insensitive Na efflux. The results obtained show that this antagonist is, in fact, able to reduce stimulation of the Na efflux by injected cAMP in a dose-dependent manner.     

Microinjection of synthetic protein kinase inhibitor into single barnacle muscle fibers before and after cyclic AMP

Single muscle fibers from the barnacle Balanus nubilus have been used as a preparation to see if a synthetic 20-residue PKI (5-24)-peptide is able to block or reverse the stimulatory response of the ouabain-insensitive Na efflux to injected cAMP. The results obtained show that this peptide behaves as a powerful inhibitor of the cAMP-mediated response and is also able to partially reverse the sustained stimulation of the Na efflux observed in ouabain-poisoned fibers following the injection of subunit A of cholera toxin.     

Microinjection of synthetic protein kinase inhibitor into single barnacle muscle fibers before and after cyclic AMP

Summary Single muscle fibers from the barnacleBalanus nubilus have been used as a preparation to see if a synthetic 20-residue PKI (5-24)-peptide is able to block or reverse the stimulatory response of the ouabain-insensitive Na efflux to injected cAMP. The results obtained show that this peptide behaves as a powerful inhibitor of the cAMP-mediated response and is also able to partially reverse the sustained stimulation of the Na efflux observed in ouabain-poisoned fibers following the injection of subunit A of cholera toxin.Warmest thanks to Prof. E. H. Fischer and Kurt Diltz for a sample of sPK1. This work received support from NSF, the Graduate School Research Committee and from NIH through a General Research Support Grant to the University of Wisconsin Medical School.