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Authordc.contributor.authorBull, Alan 
Authordc.contributor.authorMarengo, Juan José 
Authordc.contributor.authorSuárez Isla, Benjamín 
Authordc.contributor.authorDonoso P., Gonzalo 
Authordc.contributor.authorSutko, J. L. 
Authordc.contributor.authorHidalgo Tapia, María Cecilia 
Admission datedc.date.accessioned2019-01-29T12:39:52Z
Available datedc.date.available2019-01-29T12:39:52Z
Publication datedc.date.issued1989
Cita de ítemdc.identifier.citationBiophysical Journal, Volumen 56, Issue 4, 1998, Pages 749-756
Identifierdc.identifier.issn00063495
Identifierdc.identifier.other10.1016/S0006-3495(89)82722-5
Identifierdc.identifier.urihttps://repositorio.uchile.cl/handle/2250/159662
Abstractdc.description.abstractSarcoplasmic reticulum vesicles isolated from fast-twitch frog skeletal muscle presented two classes of binding sites for ryanodine, one of high affinity (Kd1 = 1.7 nM, Bmax1 = 3.3 pmol per mg) and a second class with lower affinity (Kd2 = 90 nM, Bmax2 = 7.0 pmol per milligram). The calcium channels present in the sarcoplasmic reticulum membranes were studied in vesicles fused into lipid bilayers. Low concentrations of ryanodine (5 to 10 nM) activated a large conductance calcium channel after a short delay (5 to 10 min). The activation, which could be elicited from conditions of high or low fractional open time, was characterized by an increase in channel fractional open time without a change in conductance. The open and closed dwell time distributions were fitted with the sum of two exponentials in the range of 4 to 800 ms. The activating effect of ryanodine was due to an increase of both open time constants and a concomitant decrease in the closed time constants. Under conditions of low fractional open time (less than 0.1), the time spent in long closed periods (greater than 800 ms) between bursts was not affected by ryanodine. Higher concentrations of ryanodine (250 nM) locked the channel in a lower conductance level (approximately 40%) with a fractional open time near unity. These results suggest that the activating effects of nanomolar concentrations of ryanodine may arise from drug binding to high affinity sites. The expression of the lower conductance state obtained with higher concentrations of ryanodine may be associated with the low affinity binding sites observed in frog sarcoplasmic reticulum.
Lenguagedc.language.isoen
Sourcedc.sourceBiophysical Journal
Keywordsdc.subjectBiophysics
Títulodc.titleActivation of calcium channels in sarcoplasmic reticulum from frog muscle by nanomolar concentrations of ryanodine
Document typedc.typeArtículo de revista
dcterms.accessRightsdcterms.accessRightsAcceso a solo metadatos
Catalogueruchile.catalogadorjmm
Indexationuchile.indexArtículo de publicación SCOPUS
uchile.cosechauchile.cosechaSI


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