Quercetin enhances water transport in toad bladder

A highly significant enhancement of the hydrosmotic actions both of vasopressin and of exogenous cAMP was seen in the presence of quercetin. The hypothesis is advanced that quercetin affects the intracellular coupling between Ca++ in cAMP.     

Thermal activation of the cyclic AMP stimulated sodium transport across isolated toad bladder and Na+/K+ ATPase in toad bladder homogenates

Zusammenfassung Der Temperaturkoeffizient für den durch das zyklische AMP und Theophyllin stimulierten Natriumtransport in der isolierten Krötenblase wurde analysiert. Die Enzympumpe wurde stärker beeinflusst als die mukosale Permeabilität und die Aktivität von Na⁺/K⁺ ATPase korrespondiert mit der Energie der Pumpenaktivität.     

Effects of N-ethyl maleimide on urea facilitated transport across toad gall bladder

Summary An SH reactive agent, N-ethyl maleimide (10^–3 M for 2 min in the luminal fluid) selectively inhibits the urea transpithelial flux across the toad gall bladder. Thiourea and antipyrine flux is not inhibited. The inhibitory effect on urea flux seems to be exerted on the carrier mechanism of urea transport.     

Irreversible inhibition of sodium transport by the toad urinary bladder following photolysis of amiloride analogs

Summary Active sodium transport was completely and irreversibly inhibited in toad urinary bladders photolyzed in the presence of iodeam loride.     

Effect of inhibitors of RNA and protein synthesis on the aldosterone Na+ transport response in toad bladder

Zusammenfassung Die biochemischen Wirkungen von Aldosteron in der Krötenblase wurden untersucht und der Mechanismus der Hormonwirkung diskutiert.     

Patterns of membrane organization in toad bladder epithelium: A freeze-fracture study

Summary Two cell-types of toad bladder epithelium show uncommon plasma membrane organization in freeze-fractured specimens. One type, the granular cell, contains a plasma membrane in which the A-face is poorly particulate luminally while the B-face discloses multiple large particles at this site. In contrast, the lateral and basal portions of the granular-cell membrane are typical in that more particles occupy the A-face than the B-face. In the other cell-type, which is mitochondriarich, the plasma membrane, luminally, laterally, and basally, contains rod-shaped and a few glubular particles in the A-face. We suggest that these two peculiar membrane organizations by considered in the localization of both vasopressin and aldosterone action in toad bladder.Some of these results were presented in abstract form at the 6th annual meeting of the Swiss Societies for Experimental Biology, Lausanne, 11–12, May 1974²¹ The authors are indebted to Mrs.Marthe Sidler-Ansermet, Mrs.Gorana Perrelet, MissMariella Ravazzola and Mr.Michel Bernard for valuable assistance.This work was supported in part by grants No. 3.0311.73, 3.8081.72, 3.553.75 and 3.1300.73 from Fonds National Suisse de la Recherche Scientifique, Bern, Switzerland, and by a grant-in-aid from Hoechst-Pharmaceuticals (Frankfurt-Hoechst, W. Germany).     

Drug modification of silver-induced sodium transport across toad skin

Summary Stimulation of active Na⁺ transport in the toad skin by antidiuretic hormone (ADH) and p-chloromecuribenzoate (P-CMB) was blunted by the presence of silver (Ag⁺). Amiloride inhibited active Na⁺ transport, equivalently, whether Ag⁺ was present or not.This work was supported by the Nephrology Training grant from the National Institute of Arthritis and Metabolic Diseases (1-TO1-AM-05697-02 and –03) and by Whitehall Foundation grant No. 78-156 ck-1 DSR.     

Particle aggregates in plasma and intracellular membranes of toad bladder (granular cell)

Summary Freeze-fracture of granular cells of toad urinary bladder (Bufo marinus) reveals the presence, hitherto undescribed, of intramembranous particle aggregates in intracytoplasmic structures (tubules, vacuoles and vesicles) both in resting and vasopressin-stimulated epithelia.This work was supported by grants No. 3.553.75, 3.120.77 and 3.1300.73 from the Swiss National Science Foundation.The authors are indebted to Mrs Marthe Sidler-Ansermet, Miss Jacqueline Rial and Mr Michel Bernard for valuable technical assistance.     

Competitive inhibitors of neurohypophyseal hormones on adenylate cyclase from the toad urinary bladder

Zusammenfassung Adenylat-Cyclase in plasmamembranreichen Präparationen des Epitheliums von der Harnblase der Kröte wird durch Arginine-Vasopressin aktiviert. Diese Aktivierung wird durch mehre Oxytocinanaloge, die alle eine Substitution des Glutaminrestes in Position 4 des Hormones durch Leucin oder Isoleucin gemeinsam haben, kompetitiv gehemmt. Der stärkste Antagonist der Serie ist [2,4-diisoleucin]-Oxytocin und die antagonistische Aktivität nimmt in der Reihenfolge [4-Leucin]-, [2-Isoleucin-4-leucin]-, [2,4-Dileucin]- und [2-Phenylalanin-4-leucin]-Oxytocin ab. Die Resultate werden an Hand der Oxytocinkonformation diskutiert.

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Supported by United States Public Health Service grants No. AM-13567 (RW), by the Life Sciences Foundation, Inc., and by the National Science Foundation No. GB-30716X (VJH).

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Neurohypophyseal hormone analogs are denoted in accordance with the IUPAC-IUB [Tentative Rules (Biochemistry6, 362, 1967)].     

Comparative effects of ouabain, natriuretic factor and ammonium chloride in the toad urinary bladder

Electrical changes and direct effects on Na-K ATPase activity induced by an endogenous digitalis-like natriuretic factor (NF), NH4Cl and ouabain were studied in toad bladders. NF inhibited the SCC and the Na-K ATPase activity in a similar manner to ouabain, but induced a greater increase in calculated direct current resistance (R) (p less than 0.05). NH4Cl was a weak inhibitor of Na-K ATPase activity, although it produced steeper SCC inhibition slopes than those observed with ouabain or NF (p less than 0.01). The data suggested the same mechanism of action of NF and ouabain on the sodium pump, with an additional effect of the former on apical sodium permeability of the cells and/or closure of paracellular routes leading to an increased tissue resistance. In contrast, the effects of NH4Cl were mostly compatible with intracellular inhibition of apical sodium entry into the cell.     

Inhibitory effects of 1-iodo-3-aminomethyl-5,6,7,8-tetrahydro-2-naphthol (ONO-3122) and prostaglandin H2 on vasopressin-induced osmotic water flow in toad bladder

Summary Both 1-iodo-3-aminomethyl-5,6,7,8-tetrahydro-2-naphthol (ONO-3122), which increases endogenous PGH₂, and PGH₂ itself, significantly depressed vasopressin-induced osmotic water flow in the toad bladder. These results suggest that ONO-3122 increases endogenous PGH₂ synthesis, and that PGH₂ and/or its metabolites inhibit vasopressin-induced water flow.I am grateful to Mr Y. Nara and Mrs S. Sugawara for their excellent technical assistance. This work supported in part by grant from the Life Science Laboratories.     

Involvement of a Na-K-ATPase in sodium transport by fish urinary bladder

Résumé La Na–K-ATPase sensible à l'ouabaine diminue parallèlement au transport du sodium in vitro dans la vessie urinaire de la truite (Salmo irideus) au cours de l'adaptation des animaux aux milieux salés et semble directement impliquée dans le mécanisme de ce transport.

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This work is supported by the Délégation Gélérale à la Recherche Scientifique et Technique (Contrat No. 71.7.3180).     

Colchicine dissociates the toad (Bufo arenarum) urinary bladder responses to antidiuretic hormone and to serosal hypertonicity

Resumen Los efectos de la ocitocina y la hipertonía serosa sobre la respuesta hidrosmótica de la vejiga urinaria del sapo pueden ser disociados empleando colchicina, y mas evidentemente cuando el alcaloide es colocado junto con Cu⁺⁺.