Biomaterial Database

Irreversible stimulation of hydroosmotic response in toad bladder by photoaffinity labeling with [Phe2,Phe-(p-N3)3]Vasopressin. 1983

P Eggena, and F Fahrenholz, and I L Schwartz

The photoreactive analogs of vasopressin, [Phe2,Phe-(p-N3)3]AVP (3a) and [Phe-(p-N3)2]AVP (2a), and the chemically reactive analogs of vasopressin, [Phe2,Phe-(p-NHCOCH2Br)3]AVP (3b) and [Phe-(p-NHCOCH2Br)2]AVP (2c), have been tested in the toad bladder for irreversible stimulation or inhibition of the water permeability response. Analog 3a was found to be an agonist with an ED50 of 4.5 X 10(-7) M and to induce a maximal osmotic water flow across bladders equivalent to 74% of that observed with the parent hormone (AVP). Photolysis of this analog in Ringer's fluid resulted in a decrease in its biological activity, with a half-time of 7 min. However, UV irradiation of the analog in the presence of toad bladders triggered an irreversible increase in the permeability of the bladders to water. Under optimal conditions of irradiation, water permeability remained at about 60% of maximum for more than 3 h after washout of analog 3a. The addition of AVP raised the permeability of these bladders to 100%. Analog 3a did not cause irreversible stimulation without photolysis, nor did this analog induce its characteristic effect when added to the mucosal solution. Compound 2a was found to be a potent antagonist of AVP. This inhibitory action of 2a was readily reversed in both the presence and absence of UV irradiation. Compound 3b was also found to be a reversible inhibitor of AVP. Compound 2c was found to be inactive as agonist or antagonist. These studies suggest that analog 3a binds covalently at or near the toad bladder hydroosmotic receptors, resulting in a persistent increase in permeability to water of the bladder wall.

UI	MeSH Term	Description	Entries
D009995	Osmosis	Tendency of fluids (e.g., water) to move from the less concentrated to the more concentrated side of a semipermeable membrane.	Osmoses
D010782	Photolysis	Chemical bond cleavage reactions resulting from absorption of radiant energy.	Photodegradation
D011956	Receptors, Cell Surface	Cell surface proteins that bind signalling molecules external to the cell with high affinity and convert this extracellular event into one or more intracellular signals that alter the behavior of the target cell (From Alberts, Molecular Biology of the Cell, 2nd ed, pp693-5). Cell surface receptors, unlike enzymes, do not chemically alter their ligands.	Cell Surface Receptor,Cell Surface Receptors,Hormone Receptors, Cell Surface,Receptors, Endogenous Substances,Cell Surface Hormone Receptors,Endogenous Substances Receptors,Receptor, Cell Surface,Surface Receptor, Cell
D001743	Urinary Bladder	A musculomembranous sac along the URINARY TRACT. URINE flows from the KIDNEYS into the bladder via the ureters (URETER), and is held there until URINATION.	Bladder,Bladder Detrusor Muscle,Detrusor Urinae,Bladder Detrusor Muscles,Bladder, Urinary,Detrusor Muscle, Bladder,Detrusor Muscles, Bladder
D002024	Bufo marinus	A species of the true toads, Bufonidae, becoming fairly common in the southern United States and almost pantropical. The secretions from the skin glands of this species are very toxic to animals.	Rhinella marina,Toad, Giant,Toad, Marine,Giant Toad,Giant Toads,Marine Toad,Marine Toads,Toads, Giant,Toads, Marine
D002463	Cell Membrane Permeability	A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.	Permeability, Cell Membrane
D005260	Female		Females
D000345	Affinity Labels	Analogs of those substrates or compounds which bind naturally at the active sites of proteins, enzymes, antibodies, steroids, or physiological receptors. These analogs form a stable covalent bond at the binding site, thereby acting as inhibitors of the proteins or steroids.	Affinity Labeling Reagents,Labeling Reagents, Affinity,Labels, Affinity,Reagents, Affinity Labeling
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001127	Arginine Vasopressin	The predominant form of mammalian antidiuretic hormone. It is a nonapeptide containing an ARGININE at residue 8 and two disulfide-linked cysteines at residues of 1 and 6. Arg-vasopressin is used to treat DIABETES INSIPIDUS or to improve vasomotor tone and BLOOD PRESSURE.	Argipressin,Vasopressin, Arginine,Arg-Vasopressin,Argipressin Tannate,Arg Vasopressin