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Effects of aging on induction of cardiocyte growth by extracardiac factors
M Komatsu1, S Isoyama, T Takishima
1First Department of Internal Medicine, Tohoku University School of Medicine, Sendai, Japan.
Insights
Aging significantly reduces cardiac myocyte growth induced by extracardiac factors. Myocyte growth in aged rats was less than in younger rats, indicating age-related attenuation.
Area of Science:
- Cardiovascular Biology
- Developmental Biology
- Aging Research
Background:
- Cardiac myocyte growth is crucial for heart development and repair.
- Extracardiac factors can stimulate myocyte growth.
- The impact of host aging on this growth induction is not well understood.
Purpose of the Study:
- To investigate how host rat age affects cardiac myocyte growth stimulated by extracardiac factors.
- To determine if aging attenuates the growth response of myocytes to peritoneal cavity implantation.
Main Methods:
- Neonatal rat cardiac myocytes were cultured and implanted into the peritoneal cavities of young adult and aged Wistar rats.
- Myocyte growth was assessed by measuring surface area, diameter, cell number, protein, and DNA content at various time points post-implantation.
- Comparison was made between myocytes cultured in the peritoneal cavity versus standard extracorporeal culture.
Main Results:
- Myocytes cultured within the peritoneal cavity exhibited significantly increased size, protein content per cell, and protein to DNA ratio compared to standard culture.
- Cardiac myocyte growth was significantly attenuated in aged host rats compared to younger hosts.
- Aging significantly reduces the induction of cardiac myocyte growth by extracardiac factors.
Conclusions:
- The peritoneal cavity environment promotes cardiac myocyte growth.
- Host aging significantly impairs the ability of extracardiac factors to induce cardiac myocyte growth.
- Aging attenuates cardiac myocyte growth, suggesting age-related changes affect cellular responses to growth stimuli.
Abstract:
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.