Growth effects of electrically stimulated contraction on adult feline cardiocytes in primary culture.
The purpose of this study was to determine effects of long-term electrical stimulation of cardiocyte contraction on protein synthesis rates and total protein content. Adult feline cardiocytes were plated on laminin-coated culture trays and maintained in a serum-free medium consisting of M199 supplemented with ascorbate, bovine serum albumin, creatine, carnitine, taurine, and 10(-7) M recombinant insulin. Cardiocytes were electrically stimulated to contract with use of continuous electrical pulses of alternating polarity at a frequency of 1 Hz and pulse duration of 5 ms. Nonstimulated cardiocytes are normally quiescent and were used as the control group. In control quiescent cardiocytes, protein synthesis rate decreased by 14% between days 1 and 4 in culture and then remained stable through day 7. In electrically stimulated cardiocytes, protein synthesis rates increased by 19% between days 1 and 7. Protein synthesis rates were 18% higher on day 4 and 43% higher on day 7 in electrically stimulated than in quiescent cardiocytes. Protein content per cell was determined by measuring total fluorescence per cell by use of confocal microscopy of fluorescein isothiocyanate-stained cells. Electrical stimulation significantly increased cellular protein content by 52% after 7 days compared with controls. Quiescent and electrically stimulated cardiocytes remained rod shaped, retained their myofibrillar architecture, and were responsive to electrical stimulation over the 7-day period. These data demonstrated that electrically stimulated contraction of adult cardiocytes resulted in cell growth, as assessed by an increase in protein content per cell over 7 days in culture. This increase was due, at least in part, to an acceleration of steady-state protein synthesis rates.
Kato
S
S
Department of Medicine, Gazes Cardiac Research Institute, Charleston, South Carolina, USA.
Ivester
C T
CT
Cooper
G
G
Zile
M R
MR
McDermott
P J
PJ
D000818:Animals; D002415:Cats; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000502:physiology*; D004558:Electric Stimulation / Q000295:instrumentation / Q000379:methods; D006321:Heart / Q000502:physiology*; D007328:Insulin / Q000494:pharmacology; D018613:Microscopy, Confocal; D009200:Myocardial Contraction / Q000502:physiology*; D009206:Myocardium / Q000166:cytology*; D014176:Protein Biosynthesis; D013997:Time Factors
D007328:Insulin