A simplified mechanism that mimics "adaptation" of the ryanodine receptor (RyR) has been developed and its significance for Ca2+(-)induced Ca2+ release and Ca2+ oscillations investigated. For parameters that reproduce experimental data for the RyR from cardiac cells, adaptation of the RyR in combination with sarco/endoplasmic reticulum Ca2+ ATPase Ca2+ pumps in the internal stores can give rise to either low [Cai2+] steady states or Ca2+ oscillations coexisting with unphysiologically high [Cai2+] steady states. In this closed-cell-type model rapid, adaptation-dependent Ca2+ oscillations occur only in limited ranges of parameters. In the presence of Ca2+ influx and efflux from outside the cell (open-cell model) Ca2+ oscillations occur for a wide range of physiological parameter values and have a period that is determined by the rate of Ca2+ refilling of the stores. Although the rate of adaptation of the RyR has a role in determining the shape and the period of the Ca2+ spike, it is not essential for their existence. This is in marked contrast with what is observed for the inositol 1,4,5-trisphosphate receptor for which the biphasic activation and inhibition of its activity by Ca2+ are sufficient to produce oscillations. Results for this model are compared with those based on Ca2+(-)induced Ca2+ release alone in the bullfrog sympathetic neuron. This kinetic model should be suitable for analyzing phenomena associated with "Ca2+ sparks," including their merger into Ca2+ waves in cardiac myocytes.
JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. IN THE NOVEL Invisible Man, RalphEllison's protagonist muses about the nature of history: "All things, it is said, are duly recorded-all things of importance, that is. But not quite, for actually it is only the known, the seen, the heard and only those events that the recorder regards as important that are put down ... What did they ever think of us transitory ones? ... birds of passage who were too obscure for learned classification, too silent for the most sensitive recorders of sound; of natures too ambiguous for the most ambiguous words, and too distant from the centers of historical decision to sign or even to applaud the signers of historical documents? We who write no novels, histories or other books. What about us."2 This remains one of the nagging questions for many of us who write history today. What does the historian do about what Ellison called "the void of faceless faces, of soundless voices, lying outside history"?3 There are many approaches to this problem. In Black Culture and Black Consciousness, I attempted to use folk culture-songs, tales, proverbs, jokes-to recreate the voices and consciousness of the slaves and freedmen who left few if any written sources behind them.4 I found surprisingly little need for elaborate rationales or heavy theoretical underpinnings. There was an encouraging-and perhaps all too easy-acceptance of the proposition that by examining folklore one could recover the voices of the I researched and wrote this essay while I was a Fellow at the Center for Advanced Study in the Behavioral Sciences and delivered an earlier version as the first of three Merle Curti Lectures at the University of Wisconsin, Madison, in April 1991. I am extremely grateful to my colleagues at both institutions for their help and comments. I am also indebted to Michelle Ferrari for her research assistance, to the many Berkeley students-graduate and undergraduate-who were always willing to join me in puzzling out these fascinating and perplexing problems, and to Cornelia Levine, Robert Middlekauff, James Oakes, Madelon Powers, and Lauren Smith for their perceptive readings of the final version. historically inarticulate. Underlying this acceptance was the widespread agreement that there was a valid correspondence between the creators and the receptors of folklore; since folklore came out of the community, scholars could use it to recover the common voice.In recent years, I have been trying to project this approach into the area of popular culture. More specifically, I have been attempting to recover the lost voices of large numbers of Americans during the Great Depression by a detailed examination of the mainstream popular culture they were exposed to in the books, ...
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