Search Results
You are looking at 1 - 2 of 2 items for
- Author: Yuzuru Kato x
- Refine by access: All content x
Search for other papers by Motoi Sohmiya in
Google Scholar
PubMed
Search for other papers by Yuzuru Kato in
Google Scholar
PubMed
Growth hormone (GH) and insulin-like growth factor-I (IGF-I) play important roles in erythropoiesis and erythro-poietin (EPO) secretion. We examined the effects of GH and IGF-I on EPO production in adult rat kidney and liver in vivo and in vitro. Male Wistar rats aged 8–10 weeks were used. Recombinant human GH (hGH) was continuously infused (20 μg/kg per h) subcutaneously for 48 h using a micro-osmotic infusion pump. Octreotide (10 μg/kg) was subcutaneously injected every 12 h beginning 12 h before the hGH treatment. GH increased plasma EPO levels earlier than it increased plasma IGF-I levels. At 24 h, the IGF-I content in the liver and kidney was increased from 172.8±14.6 to 232.6±17.8 ng/g tissue (means±S.E.) and from 53.8±3.1 to 112.8±7.2 ng/g tissue, respectively. The EPO content in the liver was increased from 7.5±1.2 to 15.1±1.4 mIU/g tissue at 48 h, whereas the EPO content in the kidney was decreased at 12, 24, and 48 h after the start of hGH treatment. When the kidneys were organ-cultured, hGH considerably decreased EPO levels in the culture medium in a dose-related manner. The addition of anti-hGH IgG blunted the GH-induced inhibition of EPO secretion from the kidneys. IGF-I also decreased EPO levels in the medium in a dose-related manner. The addition of anti-IGF-I IgG blunted the IGF-I-induced inhibition of EPO secretion from the kidneys, whereas the GH-induced inhibition of EPO secretion was not affected. These findings suggest that both hGH and IGF-I have direct inhibitory effects on EPO secretion from adult rat kidneys.
Search for other papers by YUZURU KATO in
Google Scholar
PubMed
Search for other papers by KAZUO CHIHARA in
Google Scholar
PubMed
Search for other papers by SHOZO OHGO in
Google Scholar
PubMed
Search for other papers by HIROO IMURA in
Google Scholar
PubMed
Recent studies in animals have demonstrated that growth hormone (GH) secretion is controlled by GH releasing factor (GHRF) and GH inhibiting factor (somatostatin). Somatostatin has not only been purified from the ovine hypothalamus, but also synthesized (Brazeau, Vale, Burgus, Ling, Butcher, Rivier & Guillemin, 1973). It has been demonstrated recently that synthetic somatostatin suppresses the spontaneous secretion of GH and the increase in plasma GH induced by i.v. injection of pentobarbitone in the rat (Brazeau, Rivier, Vale & Guillemin, 1974). We have previously reported that a single i.v. injection of isoprenaline or chlorpromazine causes a significant increase in plasma GH in the rat (Kato, Dupre & Beck, 1973). In the present experiment, we examined the effect of synthetic somatostatin (kindly supplied by Dr N. Yanaihara) on the response of plasma GH to isoprenaline or chlorpromazine in rats.
Wistar strain male rats, weighing 180–220 g, were housed in an air-conditioned room
