Title: Analysis of hyperpolarizing afterpotentials in the atrial myocardium
Authors: Nilius, Bernd ×
Boldt, W
Scheufler, K #
Issue Date: Jun-1984
Series Title: Biomedica biochimica acta. vol:43 issue:1 pages:101-10
Abstract: Afterpotentials following a train of paced action potentials in isolated pectinate muscles bordering the crista terminalis in the rabbit atrial myocardium were analyzed. Electrical measurements were performed using a standard microelectrode technique. An ultrastructural stereological analysis was undertaken to study intercellular clefts within the preparations used. After cessation of a rapid drive, afterpotentials showed an initial depolarization followed by a delayed hyperpolarization. The initial depolarization could be blocked by verapamil (13.2 microM) leaving a monotonous hyperpolarization. This hyperpolarization was modelled supposing a K+-depletion out of morphological identified intercellular clefts. From best approximation of the measured after-hyperpolarization (1) the internal K+ activity was estimated to be in the range of 82 to 90 mM depending on the pacing interval Io. It decreased due to shortening of Io; (2) the accumulated "cleft" K+ activity was estimated to be about 2 mM at a pre-drive pacing interval of 250 ms; it decreased by increasing of Io, (3) decreasing of Io accelerated the K+-depletion, (4) a single beat accumulation of about 0.28 mM was estimated. The morphologically measured geometry of the intercellular clefts (mean cleft width 0.5 micron, ratio of cleft and cell volume 0.09 +/- 0.03) agreed well with the electrophysiological findings.
ISSN: 0232-766X
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Laboratory of Ion Channel Research
Department of Cellular and Molecular Medicine - miscellaneous
× corresponding author
# (joint) last author

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