Adult rat ventricular myocytes cultured in defined medium: phenotype and electromechanical function.
We studied primary short-term cultures of adult rat ventricular myocytes in defined medium to determine whether phenotype and electromechanical function are maintained in rod-shaped, quiescent cells. Although > 80% of the myocytes retained their rod-shaped in vivo morphology for up to 72 h, contractile function as measured by cell edge motion declined 30-50% from 6 to 24 h, paralleling a 68% shortening of action potential duration. From 24 to 72 h, contractility remained unchanged. Ca2+ channel current density increased 55% after 24-48 h and then returned to the level of freshly isolated cells (9 +/- 1 pA/pF, mean +/- SE). Resting membrane potential (-71 +/- 1 mV) and action potential overshoot (34 +/- 3 mV) did not change. The ratio of alpha- to beta-myosin heavy chain mRNA and the level of cardiac alpha-actin mRNA were maintained for 8 days. Thus quiescent adult rat ventricular myocytes in defined medium undergo extensive phenotypic adaptation within 72 h of isolation, despite maintenance of a rod-shaped morphology and stable levels of contractile protein mRNA, which may limit their suitability for electrophysiological and contractile function studies.
Ellingsen
O
O
Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115.
Davidoff
A J
AJ
Prasad
S K
SK
Berger
H J
HJ
Springhorn
J P
JP
Marsh
J D
JD
Kelly
R A
RA
Smith
T W
TW
D000818:Animals; D002118:Calcium / Q000502:physiology; D002470:Cell Survival; D002478:Cells, Cultured; D003470:Culture Media; D004594:Electrophysiology; D015870:Gene Expression; D006321:Heart / Q000502:physiology*; D006352:Heart Ventricles; D009200:Myocardial Contraction; D009206:Myocardium / Q000166:cytology*; D010641:Phenotype; D051381:Rats
D003470:Culture Media; D002118:Calcium