Calcium Transient and Sodium-Calcium Exchange Current in Human versus Rabbit Sinoatrial Node Pacemaker Cells. (25th March 2013)

• Record Type: Journal Article
• Authors: Verkerk, Arie O.; van Borren, Marcel M. G. J.; Wilders, Ronald
• Other Names: Du Y. Academic Editor.; Wang Y. Academic Editor.
• Is Part Of: TheScientificWorldjournal. Volume 2013(2013)
• Publication Date: 2013-03-25
• Subjects: Science -- Periodicals; Technology -- Periodicals; Medicine -- Periodicals; 505
• DOI: 10.1155/2013/507872
• Languages: English
• ISSNs: 2356-6140

Abstract

Abstract : There is an ongoing debate on the mechanism underlying the pacemaker activity of sinoatrial node (SAN) cells, focusing on the relative importance of the "membrane clock" and the "Ca 2 + clock" in the generation of the small net membrane current that depolarizes the cell towards the action potential threshold. Specifically, the debate centers around the question whether the membrane clock-driven hyperpolarization-activated current, I f, which is also known as the "funny current" or "pacemaker current, " or the Ca 2+ clock-driven sodium-calcium exchange current, I N a C a, is the main contributor to diastolic depolarization. In our contribution to this journal's "Special Issue on Cardiac Electrophysiology, " we present a numerical reconstruction of I f and I N a C a in isolated rabbit and human SAN pacemaker cells based on experimental data on action potentials, I f, and intracellular calcium concentration ([ Ca 2 + ] i ) that we have acquired from these cells. The human SAN pacemaker cells have a smaller I f, a weaker [ Ca 2 + ] i transient, and a smaller I N a C a than the rabbit cells. However, when compared to the diastolic net membrane current, I N a C a is of similar size in human and rabbit SAN pacemaker cells, whereas I f is smaller in human than in rabbit cells.