title: Effects of arginine vasotocin and vasopressin receptor antagonists on Na+ and Cl- transport in the isolated skin of two frog species, Hyla japonica and Rana nigromaculata.
abstract: Physiological function of arginine vasotocin (AVT) and effect of receptor antagonists of vasopressin were electrophysiologically investigated on transepithelial transport of ions in the abdominal skin of Hyla japonica and Rana nigromaculata by means of the Ussing chamber system. Administrations of AVT and forskolin (adenylate cyclase activator) in the serosal side of normal Ringer's solution significantly increased transepithelial potential difference (PD) and short-circuit current (Isc) accounting for Na(+) influx, mucosal to serosal direction, across the skin of H. japonica. In contrast, AVT administrations significantly decreased PD but not Isc on the skin of R. nigromaculata in a concentration-dependent manner ranging from 10(-11) to 10(-8)M. Administration of 10(-5)M forskolin also significantly decreased PD in normal and low Na(+) Ringer's solution and in the presence of amiloride (Na(+) channel blocker) on the mucosal side of normal Ringer's solution. On the other hand, forskolin significantly increased PD and Isc in the Cl(-) free Ringer's solution. These results suggested that AVT and forskolin stimulated mainly Cl(-) influx across the skin of R. nigromaculata. In two frog species, the AVT actions on ion transports were inhibited by pretreatment of OPC-31260 (a vasopressin V(2) receptor antagonist) but not OPC-21268 (a vasopressin V(1) receptor antagonist). These results suggested that AVT activates adenylate cyclase via V(2)-like receptor and stimulates actively net Na(+) and net Cl(-) transports in the abdominal skin of H. japonica and R. nigromaculata, respectively.
authors.affiliation: Department of Life & Environmental Science, Graduate School of Science & Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Yamada
authors.forename: Tomoko
authors.initials: T
authors.lastname: Nishio
authors.forename: Yuji
authors.initials: Y
authors.lastname: Sano
authors.forename: Kazuki
authors.initials: K
authors.lastname: Kawago
authors.forename: Kouhei
authors.initials: K
authors.lastname: Matsuda
authors.forename: Minoru
authors.initials: M
authors.lastname: Uchiyama
mesh_terms: D000818:Animals; D065092:Antidiuretic Hormone Receptor Antagonists; D001001:Anura; D001552:Benzazepines / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D002712:Chlorides / Q000378:metabolism*; D005576:Colforsin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D010880:Piperidines / Q000494:pharmacology; D015363:Quinolones / Q000494:pharmacology; D017483:Receptors, Vasopressin / Q000502:physiology; D012867:Skin / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D013045:Species Specificity; D013997:Time Factors; D014668:Vasotocin / Q000494:pharmacology*
chemical_list: D065092:Antidiuretic Hormone Receptor Antagonists; D001552:Benzazepines; D002712:Chlorides; D010880:Piperidines; D015363:Quinolones; D017483:Receptors, Vasopressin; C068644:OPC 21268; C076251:mozavaptan; D005576:Colforsin; D012964:Sodium; D014668:Vasotocin