Atrial natriuretic peptide modulates amiloride-sensitive Na+ transport across the blood-brain barrier.
We obtained evidence that amiloride specifically potentiates 125I-labeled alpha-rat atrial natriuretic peptide (1-28) [atrial natriuretic peptide (ANP)-(99-126); rANP] binding to cerebral capillaries isolated from the rat cerebral cortex. The binding parameters, KD of 173 pM and Bmax of 159 fmol/mg of protein, became 33 pM and 88 fmol/mg of protein, respectively, when 10(-4) M amiloride was added to the incubation medium. When the effect of rANP was investigated on in vitro 22Na+ uptake into isolated cerebral capillaries, 10(-7) M rANP significantly inhibited the uptake in the presence of 1.0 mM ouabain, 1.0 mM furosemide, and 2.0 mM LiCl in the uptake buffer, a finding suggesting a specific inhibitory effect of rANP on amiloride-sensitive Na+ transport. Thus, the possibility that ANPs control amiloride-sensitive Na+ transport at the blood-brain barrier by interacting with specific receptors has to be considered.
Ibaragi
M
M
Department of Pharmacology 2, Nagasaki University School of Medicine, Japan.
Niwa
M
M
Ozaki
M
M
D000584:Amiloride / Q000494:pharmacology*; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000378:metabolism / Q000494:pharmacology*; D001812:Blood-Brain Barrier / Q000187:drug effects*; D002196:Capillaries / Q000378:metabolism; D002540:Cerebral Cortex / Q000098:blood supply; D002560:Cerebrovascular Circulation; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D017461:Receptors, Atrial Natriuretic Factor; D011956:Receptors, Cell Surface / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*
D011956:Receptors, Cell Surface; D000584:Amiloride; D009320:Atrial Natriuretic Factor; D012964:Sodium; D017461:Receptors, Atrial Natriuretic Factor