Enhanced proliferation of fetal rat hepatocytes in primary culture induced by ritodrine.
OBJECTIVE
Although ritodrine crosses the placenta, its direct effect on fetal cell proliferation has not been reported. We hypothesized that beta 2-adrenergic receptor stimulation could promote fetal liver growth.


METHODS
Ritodrine was added to serum- and hormone-free primary cultures of fetal, neonatal, or adult rat hepatocytes. We measured both tritiated thymidine incorporation into deoxyribonucleic acid and nucleus number. The effect of ritodrine on cell cycle was also analyzed with flow cytometry.


RESULTS
Ritodrine enhanced the proliferation of fetal rat hepatocytes. Ritodrine remarkably stimulated deoxyribonucleic acid synthesis of fetal and neonatal but not adult hepatocytes. The effect was dose dependent and was antagonized by propranolol. Analysis of the nuclear deoxyribonucleic acid content derived from flow cytometry revealed that cells stimulated by ritodrine entered S phase.


CONCLUSIONS
These results indicate that ritodrine may promote the proliferation of fetal hepatocytes through the stimulation of beta 2-adrenergic receptors, followed by induction of deoxyribonucleic acid synthesis.
Ando
H
H
Department of Obstetrics and Gynecology, School of Medicine, Nagoya University, Japan.
Kasugai
M
M
Ishihara
Y
Y
Kurauchi
O
O
Suganuma
N
N
Mizutani
S
S
Tomoda
Y
Y
D000818:Animals; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D005333:Fetus / Q000187:drug effects*; D005434:Flow Cytometry; D008099:Liver / Q000166:cytology* / Q000196:embryology / Q000378:metabolism; D051381:Rats; D012312:Ritodrine / Q000494:pharmacology*; D013936:Thymidine / Q000378:metabolism
D004247:DNA; D012312:Ritodrine; D013936:Thymidine