Received September 11, 2007
Revised October 15, 2007
Accepted after revision December 6, 2007

¹ University of Debrecen
² University of Kentucky

^* To whom correspondence should be addressed. E-mail: tbany2{at}email.uky.edu.

	Abstract

We characterized the morphological, electrical and mechanical alterations of cardiomyocytes in long term cell culture. Morphometric parameters, sarcomere length, T-tubule density, cell capacitance, ICa,L, IK1, cytosolic calcium transients, action potential and contractile parameters of adult rat ventricular myocytes were determined on each day of five days long culture. We also analyzed the health of the myocytes using an apoptotic/necrotic viability assay. The data shows that myocytes undergo profound morphological and functional changes during culture. We observed a progressive reduction in the cell area (2502±70 µm2, day 0, to 1432±50 µm2, day 5), T-tubule density, systolic shortening (0.11±0.02µm to 0.05±0.01µm) and amplitude of calcium transients (1.54±0.19 to 0.67±0.19) over five days of culture. The negative force-frequency relationship, characteristic of rat myocardium, was maintained during the first two days but diminished afterwards. Cell capacitance (156±8pF to 105±11pF) and membrane currents were also reduced (ICa,L: 3.98pA±0.39A/pF to 2.12±0.37pA/pF, I K1: 34.34p±2.31A/pF to 18.00±5.97pA/pF). We observed progressive depolarization of the resting membrane potential during culture (77.3±2.5mV to 34.2±5.9mV) and consequently, action potential morphology was profoundly altered as well. The results of the viability assays indicate that these alterations could not be attributed to either apoptosis or necrosis but rather an adaptation to the culturing conditions over time.

Key Words: Cardiac cell, Cell culture, Rat