Critically Appraise The Evidence In The Paper

J Physiol (2003), 547.2, pp. 441451 © The Physiological Society 2003 DOI: 10.1113/jphysiol.2002.034355 www.jphysiol.org Journal of Physiology gaffe of the crosswise-axial tubule frame in gene smokeing calcium sparks and calcium transients in rat atrial myocytes Malcolm M. Kirk*†, Leighton T. Izu*†, Ye Chen-Izu*, Stacey L. McCulle*, W. Gil Wier‡, C. William Balke*‡ and Stephen R. Shorofsky* Departments of *Medicine and ‡Physiology, University of Maryland School of Medicine, Baltimore, MD 21201-1541, USA cardiac atrial cells lack a invariable system of transverse tubules like that in cardiac ventricular cells. Nevertheless, many atrial cells do possess an irregular immanent transverse-axial tubular system (TATS). To investigate the possible role of the TATS in excitation muscle contraction coupling in atrial myocytes, we visualized the TATS (labelled with the fluorescent indicator, Di-8-ANEPPS) simultaneously with Ca2+ transients and/or Ca2+ sparks (fluo -4). In confocal transverse linescan images of field-stimulated cells, whole-cell Ca2+ transients had two morphologies: U-shaped transients and irregular or W-shaped transients with a varying number of points of origin of the Ca2+ transient. About fractional (54 %, n =289 cells, 13 animals) of the cells had a TATS.

Cells with TATS had a larger opine diameter (13.2 ± 2.8 mm) than cells without TATS (11.7 ± 2.0 mm) and were more earthy in the left over(p) atrium (n = 206 cells; left atrium: 76 with TATS, 30 without TATS; proficient atrium: 42 with TATS, 58 without TATS). coincident measurement of Ca2+ sparks an d sarcolemmal complaisant systems showed t! hat cells without TATS had U-shaped transients that started at the cell outskirt, and cells with TATS had W-shaped transients that began simultaneously at the cell periphery and the TATS. Most (82 out of 102 from 31 cells) extemporaneous (non-depolarized) Ca2+ sparks occurred within 1 mm of a sarcolemmal structure (cell periphery or TATS), and 33 % occurred within 1 pel (0.125 mm). We...If you want to limit a full essay, order it on our website: BestEssayCheap.com

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