RT info:eu-repo/semantics/conferenceObject
T1 Calcium signalling in cardiac muscle cells
A1 Withrow, Gil Wier
A1 López López, José Ramón
A1 Shacklock, Philip S.
A1 Balke, C. William
K1 Células cardíacas
K1 Calcio
AB In heart cells, severa! distinct kinds of transient spatial patterns of cytoplasmic calcium ion concentration ([ Ca2 + )¡) can be observed: (1) [ Ca2 + )¡ waves, in which regions of spontaneously increased [ Ca2 + ] ; propagate at high velocity (100 ¡.im/s) through the cell; (2) Ca2 + 'sparks', which are spontaneous, non-propagating changes in [ Ca2 + ] ; that are localized in small ( == 2 ¡.im) subcellular regions; and (3) evoked [ Ca2 + )¡ transients that are elicited by electrical  depolarization,  in  association  with  normal  excitation-contraction   (E­C) coupling. In confocal [ Ca2 + ] ¡ images, evoked [ Ca2 + ] ; transients appear to be nearly spatially uniform throughout the cell, except during their rising phase or during small depolarizations. In contrast to [Ca2 + )¡ waves and spontaneous Ca2 + sparks, evoked [ Ca2 + ] ; transients are triggered by L-type Ca2 + channel current and they are 'controlled', in the sense that stopping the L-type Ca2 + current stops them. Despite their different characteristics, ali three types of Ca2 + transient involve Ca2 + -induced release of Ca2 + from the sarcoplasmic reticulum. Here, we address the question of how the autocatalytic process of Ca2 + -induced Ca2 + release, which can easily be understood to underlie spontaneous regenerative ('uncontrolled'), propagating [Ca2 + )¡ waves, might be 'harnessed', under other circumstances, to produce controlled changes in [ Ca2 + ]¡, as during normal excitation-contraction coupling, or changes in [ Ca2 + )¡ that do not propagate. We discuss our observations of Ca2 + waves, Ca2 + sparks and normal Ca2 + transients in heart cells and review our results on the 'gain' of Ca2 + -induced Ca2 + release. We discuss a model involving Ca2 + microdomains beneath L-type Ca2 + channels, and clusters of Ca2 + -activated Ca2 + release channels in the sarcoplasmic reticulum which may form the basis of the answer to this question
PB University of Maryland. School of Medicine
YR 1995
FD 1995
LK http://uvadoc.uva.es/handle/10324/25024
UL http://uvadoc.uva.es/handle/10324/25024
LA eng
NO Calcium waves, gradients and oscillations. Ciba Foundation Symposium 188. Chichester: Willey, 1995, p.146-164
NO Producción Científica
DS UVaDOC
RD 18-dic-2024