ISSN:
0021-9541
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
We investigated the actions of human placental lactogen (HPL) and human growth hormone (HGH) on [3H]thymidine incorporation and the release of immunoassyable somatomedin-C (SM-C) by isolated myoblasts, dermal fibroblasts, and costal cartilage explants taken from human fetuses, at 11-21 weeks of gestation. The incorporation of [3H] thymidine by myoblasts and fibroblasts was significantly increased after incubation for 20 hr or 44 hr, and cell number after incubation for 7 days, in the presence of 50-250 ng/ml HPL. Incubation with HPL did not increase [3H]thymidine incorporation into cartilage explants, whereas incubation with HGH failed to enhance the uptake of this isotope by any of the tissues. Following extraction with acid-ethanol, culture medium conditioned by exposure to myoblasts or fibroblasts for 44 hr, and to cartilage explants for 7 days, contained radioimmunoassayable SMC. Myoblast-conditioned medium contained significantly more SM-C [1,609 ± 953 mU/mg cell protein (mean ± SD) n = 10] than did that conditioned by fibroblasts (637 ± 323; n = 5; P 〈 0.02). In 1 week of culture, cartilage explants released 4.1 ± 1.1 mU/mg wet weight (n = 7). The release of immunoassayable SM-C from cultured cells was significantly increased in the presence of 250 ng/ml HPL in five of eight experiments with myoblasts and two of four experiments with fibroblasts. Neither fibroblasts or myoblasts showed increased SM-C release following exposure to HGH.The results suggest that HPL, but not HGH, is growth-promoting for some human fetal tissues in vitro and that this action is mediated, at least in part, by an increased release of somatomedins.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jcp.1041250224
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