Modulation by NaCl of atrial natriuretic peptide receptor levels and cyclic GMP responsiveness to atrial natriuretic peptide of cultured vascular endothelial cells.
Type C atrial natriuretic peptide (ANP) receptor levels in cultured vascular endothelial cells were found to be very sensitive to NaCl and shown to be inversely related to the magnitude of ANP-induced cGMP response of the cells. Endothelial cells from bovine carotid artery were subcultured in Eagle's minimum essential medium supplemented with 10% fetal bovine serum (MEM-FBS) and in MEM-FBS plus 25 and 50 mM NaCl. Determination, after several passages, of ANP receptor levels in these cells by 125I-ANP binding assay and affinity labeling revealed a marked reduction in the number of type C receptor in the NaCl-treated cells, whereas type A receptor density was not affected. RNase protection assay to estimate the levels of type C receptor mRNA indicated that the reduction occurred at a pre-translational level. In spite of the decrease in type C receptor number and no significant change in type A receptor (i.e. particulate guanylate cyclase) levels, cGMP response of the NaCl-treated cells to ANP was greatly exaggerated; this sensitization was also observed in membrane preparations. Simple masking of type C ANP receptor with C-ANF (des-[Gln18,Ser19,Gly20,Leu21,Gly22]ANP), a ring-deleted ANP analog, did not produce any sensitization of the cGMP response to ANP; therefore, the above phenomenon cannot simply be explained by the clearance function of the type C receptor. Although whether the type C receptor depletion is directly related to the sensitization of the type A receptor/cyclase is not known, the phenomenon reported and characterized here will serve as a useful basis for elucidating ANP receptor regulation and activation.
Department of Biological Sciences, Tokyo Institute of Technology, Japan.
T
T
Katafuchi
T
T
Mizuno
H
H
Hagiwara
M
M
Itakura
T
T
Ito
S
S
Hirose
D000345:Affinity Labels; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D006162:Guanylate Cyclase / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D017461:Receptors, Atrial Natriuretic Factor; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology*
D000345:Affinity Labels; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D012965:Sodium Chloride; D009320:Atrial Natriuretic Factor; D006162:Guanylate Cyclase; D017461:Receptors, Atrial Natriuretic Factor; D006152:Cyclic GMP