Cardiac and plasma atrial natriuretic peptide after 9-day hindlimb suspension in rats.
To determine atrial natriuretic peptide (ANP) adaptation to simulated weightlessness, immunoreactive plasma (ir-NH2- and ir-COOH-terminals) and atrial (ir-COOH-terminal) ANP levels, atrial mRNA expression, immunoreactive cardiocyte ANP levels (ir-NH2- and ir-COOH-terminals), and ultrastructural observations of granules in atrial cardiocytes were assessed in male Wistar rats after a 9-day hindlimb suspension. Plasma ir-NH2- and ir-COOH-terminal ANP concentrations decreased by 17 (P < 0.05) and 37% (P < 0.05), respectively, in suspended rats. A concomitant ir-COOH-terminal ANP content reduction was also observed in left (31%; P < 0.01) and right atria (25%; P < 0.05). Atrial ANP mRNA expression was severely depleted in the right atrium and less so in the left atrium after 9 days of hindlimb suspension. Immunocytochemistry observations demonstrated lowered NH2- and COOH-terminal ANP immunoreactivities in left and right atria from suspended rats. A reduced number of storage granules (dense granules) in both atria was also noted on ultrastructural analysis. It was concluded that ANP biosynthesis, storage, and release were decreased after a 9-day hindlimb suspension.
Fareh
J
J
Laboratoire de Physiologie de l'Environment, Faculté de Médecine Lyon Grange, Blanche, Lyon, France.
Bayard
B
B
Gabrion
J
J
Thibault
G
G
Oliver
J
J
Bouille
C
C
Gauquelin
G
G
Gharib
C
C
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000097:blood* / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D006614:Hindlimb; D008297:Male; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism*; D015345:Oligonucleotide Probes / Q000235:genetics; D010446:Peptide Fragments / Q000097:blood / Q000378:metabolism; D011498:Protein Precursors / Q000097:blood / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D014893:Weightlessness
D015345:Oligonucleotide Probes; D010446:Peptide Fragments; D011498:Protein Precursors; D012333:RNA, Messenger; C055659:atrial natriuretic factor prohormone (1-98); D009320:Atrial Natriuretic Factor