AJP - Heart and Circulatory Physiology, Vol 266, Issue 6 2279-H2286, Copyright © 1994 by American Physiological Society
Effects of aging on induction of cardiocyte growth by extracardiac factors
M. Komatsu, S. Isoyama and T. Takishima
First Department of Internal Medicine, Tohoku University School of Medicine, Sendai, Japan.
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.
