Calcium fluxes, ion currents and dihydropyridine receptors in a new immortal cell line from rat heart muscle.
A cell line (RCVC) in permanent culture was developed from adult rat ventricular cells; transformation was attained by incubation with conditioned media from UCHT1, a rat thyroid cell line. Immortalized ventricular cells have a doubling time of 20 h, contact inhibition of growth, and display some muscle markers such as a high glycogen content and positive immunoreaction for myoglobin, alpha-sarcomeric actin, alpha-actinin and desmin. A microsomal fraction from these cells was shown to bind 3H-nitrendipine with a maximal capacity of 295 fmol/mg protein and an equilibrium dissociation constant of 0.7 nM. Nifedipine-sensitive 45Ca2+ influx was evident in partially depolarized cells (40 mM K+ in the incubation medium). An equivalent influx, induced by the calcium channel agonist BAYK-8644 and CGP-28392, was obtained in normally polarized cells. Patch clamp studies show slow inward currents that can be completely blocked by 5 microM nifedipine; cells were induced to further differentiation by culturing in a hormone supplemented medium for 30 days. Under this condition, fast, inactivating inward currents and a large outward current became apparent. After 40-60 days, the cells exhibit La(3+)-sensitive fast and slow inactivating inward currents that resemble T and L-type Ca2+ currents. This cell line appears to be a good model system for the investigation of cardiomyocyte differentiation in situ.
Caviedes
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Departamento de Fisiologia y Biofisica, Facultad de Medicina, Universidad de Chile, Santiago.
Olivares
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E
Salas
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K
Caviedes
R
R
Jaimovich
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E
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000493:pharmacokinetics*; D002120:Calcium Channel Agonists / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology*; D020746:Calcium Channels, L-Type; D002454:Cell Differentiation / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D002460:Cell Line; D006321:Heart / Q000502:physiology*; D007150:Immunohistochemistry; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D009124:Muscle Proteins / Q000502:physiology*; D009206:Myocardium / Q000737:chemistry / Q000166:cytology* / Q000378:metabolism; D009568:Nitrendipine / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D011916:Rats, Inbred F344; D013997:Time Factors; D014316:Tritium
D002120:Calcium Channel Agonists; D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D009124:Muscle Proteins; D011725:Pyridines; D014316:Tritium; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; C040525:CGP 28392; D009568:Nitrendipine; D002118:Calcium