Regulation of atrial natriuretic hormone production by triiodothyronine in cultured rat atrial myocytes.
Since thyroid hormones have been reported to increase the synthesis of rat atrial natriuretic hormone and its mRNA accumulation, we further investigated the mechanism of stimulation of rANH synthesis by T3 using cultured rat atrial myocytes. T3 (10(-9)-10(-7) mol/l) increased cellular content and secretion into the medium of immunoreactive rANH in a dose-dependent manner. However, the ratio of secreted/cellular rANH was not altered by the addition of T3. Furthermore, in both cellular and secreted rANH, the larger molecular form (gamma-rANH) apparently predominated over the smaller one (alpha-rANH), and this profile was not influenced by T3 (10(-7) mol/l). Although T3 (10(-9)-10(-7) mol/l) also increased cellular rANH mRNA accumulation, the ratio of cellular rANH/rANH mRNA was not changed. Moreover, using actinomycin D, we found that T3 (10(-7) mol/l) did not affect the degradation of rANH mRNA. From these findings, we suggest that T3 has no specific effects on the translational and posttranslational processes and the release of rANH, but that T3 stimulates rANH synthesis in the pretranslational levels, probably in the transcriptional level of rANH gene.
Mori
Y
Y
Second Department of Internal Medicine, Kansai Medical University, Osaka, Japan.
Nishikawa
M
M
Matsubara
H
H
Toyoda
N
N
Masaki
H
H
Yonemoto
T
T
Takagi
T
T
Inada
M
M
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D002850:Chromatography, Gel; D004305:Dose-Response Relationship, Drug; D009206:Myocardium / Q000166:cytology* / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D011863:Radioimmunoassay; D051381:Rats; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics; D014284:Triiodothyronine / Q000494:pharmacology*
D012333:RNA, Messenger; D014284:Triiodothyronine; D009320:Atrial Natriuretic Factor