Covalent labeling of hydrosmotic toad bladder receptors with an antagonist of vasotocin

Journal Article · Mon Jun 01 00:00:00 EDT 1987 · Am. J. Physiol.; (United States)

OSTI ID:6467469

Eggena, P; Buku, A; Ma, C L; Somoza, L I; Wyssbrod, H R; Schwartz, I L; Glass, J D

A photoreactive analogue of vasotocin, (1-desamino,4-lysine(azidobenzoyl),8-arginine)vasotocin (4-N3-AVT), has been examined in the isolated toad urinary bladder for biological activity and binding to hormonal receptors. Although 4-N3-AVT induced only a small increase in bladder permeability to water, it behaved as a potent inhibitor of hydrosmotic action of (8-arginine)vasotocin (AVT) and (8-arginine)vasopressin (AVP). The inhibitory action of 4-N3-AVT was readily reversed on removal of the analogue from the serosal bathing solution. On the other hand, when bladders were exposed to 4-N3-AVT in the presence of long wavelength UV light (365 nm), the inhibition by 4-N3-AVT was not reversed on washout of the analogue. The dose of vasopressin required for a half-maximal response (ED50 value) was increased from 5 X 10(-9) to 1.3 X 10(-7) M in bladders photolabeled with 4-N3-AVT and the maximal response capacity of the tissue (intrinsic activity) was reduced to 79% of nonphotolabeled controls. A crude membrane preparation derived from bladders photolabeled with 4-N3-AVT contained 72 fmol of specific binding sites for tritium-labeled vasopressin per milligram protein, whereas nonphotolabeled controls had 136 fmol of specific binding sites per milligram protein. These observations suggest that 4-N3-AVT forms a covalent bond with hydrosmotic receptors in the presence of UV light. This is the first antagonistic photoaffinity analogue observed in the toad bladder and it may serve as a useful tool for analyzing the cellular mechanism of action of antidiuretic hormone.

• Research Organization: Mount Sinai School of Medicine, New York, NY
• OSTI ID: 6467469
• Journal Information: Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States)
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
CELL MEMBRANES
PERMEABILITY
VASOPRESSIN
BIOCHEMICAL REACTION KINETICS
RECEPTORS
BIOLOGICAL RADIATION EFFECTS
BLADDER
COVALENCE
DOSE-RESPONSE RELATIONSHIPS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ULTRAVIOLET RADIATION
BIOLOGICAL EFFECTS
BODY
CELL CONSTITUENTS
ELECTROMAGNETIC RADIATION
HORMONES
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MEMBRANE PROTEINS
MEMBRANES
ORGANIC COMPOUNDS
ORGANS
PEPTIDE HORMONES
PITUITARY HORMONES
PROTEINS
RADIATION EFFECTS
RADIATIONS
REACTION KINETICS
URINARY TRACT
560120* - Radiation Effects on Biochemicals
Cells
& Tissue Culture