Thyroidal ANF: a possible mediator of autocrine regulation in the porcine thyroid gland.
Atrial natriuretic factor immunoreactivity (ir-ANF) was examined in thyroid tissue sections and cultured thyroid cells using immunohistochemical staining with a monoclonal anti-ANF antibody. Localization of ir-ANF in perinuclear granules in cultured cells and in the basal region of follicular cells in sectioned tissue suggests that ir-ANF is a basally secreted product. Thyroidal ir-ANF was also characterized using reversed phase high performance liquid chromatography (RP-HPLC) of acidic thyroid extracts. An ir-ANF peak coeluting with synthetic rat ANF(99-126) suggests that thyroidal ir-ANF may be identical in form to circulating atrial ANF. However, the detection of ir-ANF in cultured thyroid cells confirms that the immunoreactivity is locally produced. Saturation analysis revealed high affinity ANF receptors (Kd = 0.1 nM; MBC = 17.2 fmol/mg protein) on these cultured cells, and a competition study demonstrated the ability of extracted thyroidal ir-ANF to inhibit 125I rat ANF binding to the membrane receptors. The evidence presented here suggests that ir-ANF in the thyroid may be secreted locally to exert an autocrine effect on neighboring follicular cells.
Hughes
C E
CE
Department of Medicine (Division of Endocrinology), Uniformed Services University of the Health Sciences, Bethesda, MD 20814-4799.
Sellitti
D F
DF
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D001665:Binding Sites; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D004797:Enzyme-Linked Immunosorbent Assay; D007150:Immunohistochemistry; D010446:Peptide Fragments / Q000037:antagonists & inhibitors / Q000378:metabolism; D011863:Radioimmunoassay; D051381:Rats; D013552:Swine; D013961:Thyroid Gland / Q000166:cytology / Q000378:metabolism*
D010446:Peptide Fragments; D009320:Atrial Natriuretic Factor