title: Effects of atrial natriuretic peptide on bicarbonate transport in long- and short-looped medullary thick ascending limbs of rats.
abstract: Atrial natriuretic peptide (ANP) is known to influence NaCl transport in the medullary thick ascending limbs (MAL), where the largest NaCl reabsorption occurs among distal nephron segments in response to arginine vasopressin (AVP). In the present study, we investigated the effect of ANP on bicarbonate (HCO3 (-)) transport in the MAL using an isolated tubule perfusion technique. The HCO3 (-) concentration was measured using free-flow ultramicro-fluorometer. We first observed basal HCO3 (-) reabsorption in both long- and short-looped MALs (lMALs, and sMALs, respectively). AVP inhibited HCO3 (-) reabsorption in both lMALs and sMALs, whereas ANP did not change HCO3 (-) transport. However, in the presence of AVP, ANP restored the HCO3 (-) reabsorption inhibited by AVP both in lMAL and sMAL. The effects of ANP on HCO3 (-) transport was mimicked by cyclic GMP. The mRNA expression level of the vasopressin V2 receptor in lMALs was significantly higher than in sMALs, whereas expression of the V1a receptor was unchanged. In summary, AVP inhibits HCO3 (-) transport, and ANP counteracts the action of AVP on HCO3 (-) transport both in lMALs and sMALs.
authors.affiliation: Department of Internal Medicine and Education & Research Center, Kitasato University Medical Center, Kitamoto, Saitama, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nonoguchi
authors.affiliation: Systems Biology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Izumi
authors.affiliation: Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Kumamoto, Japan.
authors.forename: Yushi
authors.initials: Y
authors.lastname: Nakayama
authors.affiliation: Department of Pharmacy, Kumamoto University Hospital, Kumamoto, Kumamoto, Japan.
authors.forename: Takanobu
authors.initials: T
authors.lastname: Matsuzaki
authors.affiliation: Department of Physiology, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Yasuoka
authors.affiliation: Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Kumamoto, Japan.
authors.forename: Takeaki
authors.initials: T
authors.lastname: Inoue
authors.affiliation: Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Kumamoto, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Inoue
authors.affiliation: Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Kumamoto, Japan.
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Mouri
authors.affiliation: Department of Physiology, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan.
authors.forename: Katsumasa
authors.initials: K
authors.lastname: Kawahara
authors.affiliation: Department of Pharmacy, Kumamoto University Hospital, Kumamoto, Kumamoto, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Saito
authors.affiliation: Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Kumamoto, Japan.
authors.forename: Kimio
authors.initials: K
authors.lastname: Tomita
mesh_terms: D000818:Animals; D001127:Arginine Vasopressin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D001639:Bicarbonates / Q000378:metabolism*; D006152:Cyclic GMP / Q000494:pharmacology; D015870:Gene Expression; D017136:Ion Transport / Q000187:drug effects; D007679:Kidney Medulla / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D010477:Perfusion; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017483:Receptors, Vasopressin / Q000235:genetics / Q000378:metabolism; D012212:Rheology; D046509:Tissue Culture Techniques
chemical_list: D001639:Bicarbonates; D012333:RNA, Messenger; D017483:Receptors, Vasopressin; D001127:Arginine Vasopressin; D009320:Atrial Natriuretic Factor; D006152:Cyclic GMP