Effects of aging on induction of cardiocyte growth by extracardiac factors.
To examine the effect of aging on the induction of cardiac myocyte growth by extracardiac factors, we cultured myocytes obtained from neonates of the same litter and implanted them into the peritoneal cavity of developmental phase (2-mo-old), young adult (7-mo-old), and aged (18-mo-old) host Wistar rats. Hearts obtained from 2- to 4-day-old neonates were dissociated with gentle trypsinization, and cells were seeded in culture wells and inserts. The culture insert (9 mm in diam) has a thin membrane the pore size of which is 0.45 microns. After 24 h of usual extracorporeal incubation in the serum-supplemented medium, the inserts were implanted into the peritoneal cavity of the host rats of the three age groups. Zero, 24, 72, and 96 h after implantation into the peritoneal cavity, the inserts were removed from the peritoneal cavity. Surface area of plated myocytes, diameter, number, protein, and DNA content of the suspended cells were measured. Size, protein content per cell, and protein per DNA of cells implanted into the peritoneal cavity were significantly greater than those cultured in the usual extracorporeal method. Growth of the myocytes cultured in the peritoneal cavity of aged host rats was significantly less compared with that of myocytes implanted in the peritoneal cavity of younger rats. Thus aging attenuates the induction of cardiac myocyte growth by extracardiac factors.
First Department of Internal Medicine, Tohoku University School of Medicine, Sendai, Japan.
M
M
Komatsu
S
S
Isoyama
T
T
Takishima
D000375:Aging / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D002452:Cell Count; D002455:Cell Division; D017690:Cell Transplantation; D002478:Cells, Cultured; D009200:Myocardial Contraction; D009206:Myocardium / Q000166:cytology*; D010529:Peritoneal Cavity / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar