Gene regulation of atrial natriuretic peptide A, B, and C receptors in rat glomeruli.
METHODS
Atrial natriuretic peptide (ANP) has three types of receptor. We investigated the gene regulation of three types of ANP receptors (ANPR-A, B, and C) in rat glomeruli using reverse transcription coupled with competitive polymerase chain reaction (PCR).


RESULTS
Competitive PCR revealed that ANPR-C mRNA expression was most abundant (ANPR-C > A >> B) in glomeruli from control rats among mRNA expressions of three receptors, which were 20- to 15,000-fold higher than those in inner medullary collecting ducts. Two days' dehydration caused reversible decreases of ANPR-A, B, and C mRNAs by 50-80%. To determine the mechanisms of down-regulation of mRNA expression, isolated glomeruli were incubated in isotonic or hypertonic solution. Hyperosmolality induced by NaCl, mannitol or raffinose caused significant increases of ANPR-A, B, and C mRNA expression. Hypertonicity by urea showed smaller effects. ANP stimulated the expression of ANPR-A, B, and C mRNA in vitro.


CONCLUSIONS
These results indicate that dehydration caused reversible decreases of ANPR-A, B, and C mRNA expression in glomeruli, and these decreases were not caused by increased plasma osmolality but probably by lower circulating levels of ANP.
Itoh
K
K
Third Department of Internal Medicine, Kumamoto University School of Medicine, Kumamoto, Japan.
Nonoguchi
H
H
Shiraishi
N
N
Tomita
K
K
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology; D001667:Binding, Competitive; D001769:Blood; D006152:Cyclic GMP / Q000378:metabolism; D003681:Dehydration / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006982:Hypertonic Solutions; D007678:Kidney Glomerulus / Q000378:metabolism*; D008297:Male; D008353:Mannitol / Q000008:administration & dosage; D009994:Osmolar Concentration; D012333:RNA, Messenger / Q000378:metabolism; D011887:Raffinose / Q000008:administration & dosage; D051381:Rats; D017207:Rats, Sprague-Dawley; D017461:Receptors, Atrial Natriuretic Factor / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012462:Saline Solution, Hypertonic; D014556:Urine
D006982:Hypertonic Solutions; D012333:RNA, Messenger; D012462:Saline Solution, Hypertonic; D008353:Mannitol; D009320:Atrial Natriuretic Factor; D017461:Receptors, Atrial Natriuretic Factor; D006152:Cyclic GMP; D011887:Raffinose