title: Synthesis and characterization of a long-acting fluorescent analog of vasotocin.
abstract: This study reports the synthesis of l-desamino-7-lysine- (fluorescein)-8-arginine-vasotocin (7-lys(flu) dAVT), and describes its biological activity in the isolated urinary bladder of the toad Bufo marinus. 7-lys(flu)dAVT was fully active in increasing bladder permeability to water. A half-maximal hydroosmotic response was obtained at a concentration of 3 x 10(-8) M. A unique feature of this analog was that its response was not readily reversed after removal of the analog from the serosal bathing solution. The residual response to 7-lys(flu) dAVT was abolished (reversibly) by reducing serosal bath pH from 7.4 to 6.0, suggesting that acidification inhibits the response to analog at a step after the interaction of the ligand with its receptor. Although 8-arginine-vasopressin (AVP) was about 20 times more potent than 7-lys(flu)dAVT in increasing membrane permeability to water, the response to AVP was readily reversed. Preincubation of bladders with 7-lys(flu)dAVT in the presence of AVP blocked the residual response to 7-lys(flu) dAVT. These studies suggest that 7-lys(flu)dAVT forms a stable and physiologically active complex with hydrosmotic toad bladder receptors, and it may, therefore, serve as a useful fluorescent marker for receptors in tissues from this and other species that use vasotocin as an antidiuretic/pressor principle.
authors.affiliation: Department of Physiology and Biophysics, Mount Sinai School of Medicine, New York, NY 10029.
authors.forename: P
authors.initials: P
authors.lastname: Eggena
authors.forename: A
authors.initials: A
authors.lastname: Buku
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D002024:Bufo marinus; D005260:Female; D066298:In Vitro Techniques; D007202:Indicators and Reagents; D008969:Molecular Sequence Data; D010539:Permeability; D013329:Structure-Activity Relationship; D001743:Urinary Bladder / Q000187:drug effects / Q000502:physiology*; D014668:Vasotocin / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D007202:Indicators and Reagents; D001127:Arginine Vasopressin; C061671:vasotocin, 1-deamino-Lys(7)-(fluorescein)-Arg(8)-; D014668:Vasotocin