ArticleThe journal of physiological sciences : JPS2009
Inhomogeneous distribution of action potential characteristics in the rabbit sino-atrial node revealed by voltage imaging.
Article in The journal of physiological sciences : JPS, 2009. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers.
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2 citing papers in PubMed.
- Initiation and entrainment of multicellular automaticity via diffusion limited extracellular domains.Biophysical journal · 2021Article
- Computational modeling of inhibition of voltage-gated Ca channels: identification of different effects on uterine and cardiac action potentials.Frontiers in physiology · 2014Article
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3 authors.
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Abstract
The sino-atrial node (SAN) is the natural pacemaker of the heart. Mechanisms of the leading pacemaker site generation and dynamic pacemaker shifts in the SAN have been so far studied with an electrophysiological technique, but the detailed spatial distribution of action potential characteristics in the SAN has not been analyzed due to the limited number of simultaneously recorded sites in microelectrode recording. To elucidate the mechanism of leading pacemaker site generation in the SAN, we applied a voltage imaging technique and analyzed the spatial distribution of action potential characteristics in the rabbit SAN. Action potential parameters, i.e., action potential duration at 50% repolarization level, the slope of upstroke, and the slope of the linearly depolarizing early phase of pacemaker activity (phase-4), were calculated from optical signals. Action potential parameter values derived from intracellular recording with a microelectrode and those from optical recording were significantly correlated. The leading pacemaker site occurred in the region of either globally or locally maximum phase-4 slope in 7 of 12 preparations, however, it did not coincide with the region of the early maximum phase-4 slope in the other 5 preparations. Carbenoxolone, a gap junction blocker, changed action potential properties and caused pacemaker shifts. Model simulation, assuming an inhomogeneous distribution of intrinsic properties of SAN cells, reproduced the experimental results. We conclude that the functional structure of the SAN is more inhomogeneous than that dictated by previous models. Besides intrinsic cellular properties, cell-to-cell interaction through gap junctions influences action potential characteristics and leading pacemaker site generation.
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