The electrophysiology of adult cat cardiac ventricular myocytes: changes
during primary culture.
Schackow, T. Eric, Robert S. Decker, and Robert E. Ten Eick.
Department of Molecular Pharmacology and Biological Chemistry, Department
of Cell, Molecular, and Structural Biology, and The Feinberg Cardiovascular
Center, Northwestern University, Chicago, Illinois 60611
APStracts 2:0011C, 1995.
To investigate the nature of electrophysiologic changes in adult cat cardiac
ventricular myocytes that may occur when cells are maintained in primary
culture for 1-2 weeks, the electrophysiology of cells freshly isolated from
collagenase-perfused hearts (day 0 controls) was compared with that of cells
maintained in primary culture for up to 14 days either 1) on a two
-dimensional (2D) surface (laminin-coated coverslips), which allowed for
changes in cellular morphology; or 2) in a three-dimensional (3D) alginate
matrix, which minimized changes in cell shape. Action potentials and whole
-cell ionic currents were recorded using a conventional whole-cell-patch
technique. Whereas both cellular resting potential and the depth of the
&AMPQUOTnotch&AMPQUOT terminating phase 1 were diminished relative to controls in 2D- and
3D-cultured cells, the action potential duration and the incidence of early
afterdepolarizations (EADs) were increased relative to controls in 2D
-cultured cells but not in 3D-cultured cells. Corresponding alterations in
whole-cell ionic currents included a 40% reduction in IK1 conductance (GK1)
and a 90% reduction in Ito conductance (Gto) in both 2D- and 3D-cultured
cells relative to day 0 controls and a 50% increase in ICa-L conductance (GCa
-L) in 2D-cultured cells relative to both 3D-cultured cells and day 0
controls. The reduction in Gto in long-term culture was half-maximal by days
7-8 and could not be attributed to reduced Ito availability, involvement of a
noninactivating Ito, the cell culture procedure itself, or the presence of
serum in the culture media. In day 0 cells from a heart with right
ventricular hypertrophy Gto was larger than in day 0 normal control cells and
was reduced subsequent to placing them in 3D-culture for 19 days. The results
suggest that both long-term culture and change in cellular morphology can
affect the electrophysiology of cardiac ventricular myocytes.
Received 9 November 1993; accepted in final form 27 September 1994
APS Manuscript Number C0575-3.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1994 The American Physiological Society.
Published in APStracts on 27 February 1995.