Quercetin enhances water transport in toad bladder

Summary A highly significant enhancement of the hydrosomotic 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⁺⁺ and cAMP.This work was supported by the Swiss National Science Foundation, grant No. 3.043-0.76.     

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.     

Multinucleated cells in the retinal pigment epithelium: A scanning electron microscopic study

Summary Multinucleated cells in the retinal pigment epithelium of the albino rat are shown with the scanning electron microscope beside normal mononucleated cells. We suggest that such elements are formed during foetal life, owing to the absence of any mitotic activity in adult rats.     

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.     

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.     

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.     

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)].     

Refeeding of mice after fasting stimulates cell renewal in the gall bladder epithelium

Summary The effect of refeeding of mice after a fasting period on the uptake of 3H-thymidine and on mitotic activity in the gall bladder epithelium was studied by histoautoradiography. A significant increase in both DNA synthesis and mitotic activity was observed after 12 h of refeeding.Acknowledgments. This work was supported by the Fonds voor Geneeskundig Wetenschappelijk Onderzoek and by the Algemeene Spar-en Lijfrentekas.     

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.     

An electron microscope study of nerves in the corneal epithelium

Zusammenfassung Eine elektronenmikroskopische Untersuchung der Nerven des Hornhautepithels der Mäuse hat ergeben, dass die Nervenfasern in tiefen Rinnen in den basalen Epithelzellen liegen. So scheint es, dass die Nervenfasern innerhalb der Zellen liegen, obgleich in Wirklichkeit die Fasern von der Zellmembran umhüllt sind.     

Carbonic anhydrase type II in regenerating retinal pigment epithelium. A histochemical study in the rabbit

Type II carbonic anhydrase (CAII) in the cytoplasm of the retinal pigment epithelium (RPE) may contribute to the transport of water and solutes across the RPE. The activity of this enzyme in RPE during its response to damage, e.g., during regeneration, is therefore of interest in understanding retinal disease. Immuno-histochemistry was used to compare CAII activity of normal RPE and RPE experimentally induced to regenerate. In normal rabbits, the RPE stained intensely with a peroxidase-linked antibody specific for human CAII. Regenerating RPE stained less intensely. Within the regenerating epithelium, staining appeared more intense in mature cells than in immature ones, suggesting that CAII activity gradually returns during RPE regeneration.     

The characteristic appearance of label in the urinary bladder epithelium following injection ofd,l-tryptophan-H3 in mice

Zusammenfassung Nach subkutaner oder intraperitonealer Injektion vond,l-Tryptophan-H³ wurde radioautographisch eine charakteristische, starke Radioaktivität in den oberflächlichen Epithelzellen der Mausharnblase gefunden. Nach Unterbindung der beiden Ureter vor der Injektion unterblieb die meiste Radioaktivität. Die Resultate scheinen darauf hinzuweisen, dass die Radioaktivität auf dem im Harn ausgeschiedenen markierten Tryptophan oder auf seinen Abbauprodukten, die während einiger Zeit in oberflächlichen Epithelzellen adsorbiert und gespeichert wurden, beruht.     

An unusual basement membrane underlying intestinal epithelium of the platypus (Ornithorhynchus anatinus)

Zusammenfassung Es werden die besonderen strukturellen Eigenschaften der Basalmembran beschrieben, die unter dem Mucosaepithel aller Darmregionen (Magen bis Rectum) des Schnabeltiers (Ornithorhynchus anatinus) liegt.     

Use of3H-QNB in the isolation of plasma membrane from smooth muscle of the urinary bladder: Effect of oxalate on calcium uptake by the membrane fractions

Summary Specific binding of tritiated quinuclidinyl benzilate (³H-QNB) to surface membrane muscarinic receptors was utilized to identify plasma membrane (PM) fractions from smooth muscle of the rabbit urinary bladder. Accumulation of³H-QNB in the PM fraction was 4–5-fold higher than that in fractions of endoplasmic reticulum (EM) or mitochondria (M). A similar pattern of     

Use of 3H-QNB in the isolation of plasma membrane from smooth muscle of the urinary bladder: effect of oxalate on calcium uptake by the membrane fractions

Specific binding of tritiated quinuclidinyl benzilate (3H-QNB) to surface membrane muscarinic receptors was utilized to identify plasma membrane (PM) fractions from smooth muscle of the rabbit urinary bladder. Accumulation of 3H-QNB in the PM fraction was 4-5-fold higher than that in fractions of endoplasmic reticulum (EM) or mitochondria (M). A similar pattern of distribution was found for 5'-nucleotidase. 3H-QNB binding therefore appears to be a suitable marker for plasma membrane of the urinary bladder. Data on ATP-dependent calcium uptake by PM and ER fractions showed that oxalate highly potentiated calcium uptake by both fractions and consequently this feature cannot be used to identify ER fractions specifically.