FUKASAWA Manabu Yamagata Univ., Sch. of Med., Instructor, 医学部, 助手 (90218876)
SHIMANUKI Takao Yamagata Univ., Sch. of Med., Instructor, 医学部, 助手 (90211284)
WASHIO Masahiko Yamagata Univ., Sch. of Med., Prof., 医学部, 教授 (20018310)
|Budget Amount *help
¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1992 : ¥200,000 (Direct Cost : ¥200,000)
Fiscal Year 1991 : ¥1,800,000 (Direct Cost : ¥1,800,000)
Neonatal cardiac myocytes (CMs) and fibroblasts (CFs) have various potential capacities including cell proliferation, growth, and differentiation. In addition, CMs interact with and are modified by the presence of CFs. In this study, we evaluated the modulation of CM beating, growing and hypothermic injury by CFs. CMs and CFs were isolated from neonatal rat ventricles and cultures of myocyte only or in co-culture with CFs were established. A CM and CF concentration of 2.5 x 10^B cells/ml was chosen and the proportion of CF was determined to be 33% (ml CM: ml CF) as follows: 4:0 (group C), 4:2 (group M-F). In the normothermic study, CMs and CFs were cultured for 21 days,and myocyte beating rate and hypertrophy were evaluated. In the hypothermic study, cells were incubated at 4 ﾟC for 12, 18, 24, 36 and 48 hrs on the 4th day of culture,, and the enzyme release (CPK and LDH) and the recovery of CM beating rate were measured.
CM beating of group C increased rapidly with peak value on day 5 (265 beats/min), which continued for 5 days, and then decreased. In group M-F, the increase of CM beating was markedly suppressed, however, the enlargement of CM volume was stimulated (133% of control group myocyte). In the hypothermic study, the recovery ratio of CM beating rate in group C decreased at 18 hrs (55.6% of control), reaching null levels at 48 hrs. However, group M-F showed a significantly increased recovery (at 18 hours: 95.7%; at 48 hours: 27.6%). Release of CPK and LDH in group C increased gradually by 24 hours, and showed a marked increase at 48 hours (CPK:816 mIU/flask, LDH:1186 mIU/flask). However, the levels of CPK and LDH in group M-F were significantly lower at 18 hours, and the greatest difference was observed at 48 hours (CPK:216, LDH:473). Thus, cardiac fibroblasts suppressed the myocyte beating, stimulated the hypertrophy and protected the hypothermic injury. These results indicated that fibroblasts controlled cardiac myocyte viability and growth.