Quiescent adult rat ventricular myocytes cultured in defined medium undergo extensive phenotypic adaptation within 72 h, including a 30-50% decline in contractile 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 et al. (Sun,) conducted a other in Adult rat ventricular myocytes. Culturing in defined medium vs. Freshly isolated cells was evaluated on Phenotype and electromechanical function. Quiescent adult rat ventricular myocytes cultured in defined medium undergo extensive phenotypic adaptation within 72 h, including a 30-50% decline in contractile function.
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