Isolation of large sheets of frog skin epidermis

Zusammenfassung Nach Trypsinbehandlung abgetrennte Froschepidermis von bis zu 5 cm ø zeigt dieselbe Potenialdifferenz, Stromkurzschluss- und Sulfatpermeabilität wie die unveränderte Froschhaut. Die präparierte Epidermis besitzt fast keine Hautdrüsen, Jedoch fast völlig verschlossene Drüsenausführungsgänge.

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This work was supported by grants from the U.S. Public Health Service No. AM 05865 and No. GM 00899.     

Colchicine inhibition of ADH effect on frog skin permeability

Summary ADH and AMPc enhance both thiourea unidirectional fluxes in frog skin. This effect is completely abolished by colchicine pretreatment. The ADH increase of thiourea discharge with or without colchicine led us to suppose that colchicine does not directly affect ADH action on outer membrane permeability, but exerts its effects on a site which is limiting for the ADH action on transepithelial permeability.The present work has been supported by C.N.R., Rome.     

Colchicine inhibition of ADH effect on frog skin permeability

ADH and AMPc enhance both thiourea unidirectional fluxes in frog skin. This effect is completely abolished by colchicine pretreatment. The ADH increase of thiourea discharge with or without colchicine led us to suppose that colchicine does not directly affect ADH action on outer membrane permeability, but exerts its effects on a site which is limiting for the ADH action on transepithelial permeability.     

Depolarizing action of K-strophantine and K-strophantoside on isolated frog skin

Résumé Après une rapide revue de la littérature, les auteurs rendent compte des résultats de leur étude sur l'action dépolarisante de la strophantine K et du strophantoside K sur la peau isolée de la grenouille. Les résultats démontrent, selon les auteurs, que la strophantine K et le strophantoside K ont la même action sur les potentiels de la peau de la grenouille que sur le myocarde. L'action dépolarisante peut être mise en corrélation avec la sortie des K⁺ions et le transport actif des Na⁺ ions dans la membrane des cellules épithéliales de la peau de la grenouille.      

Structural diversity and species distribution of host-defense peptides in frog skin secretions

Cationic peptides that adopt an amphipathic α-helical conformation in a membrane-mimetic environment are synthesized in the skins of many frog species. These peptides often display cytolytic activities against bacteria and fungi consistent with the idea that they play a role in the host’s system of defense against pathogenic microorganisms, but their importance in the survival strategy of the animal is not clearly understood. Despite the common misconception that antimicrobial peptides are synthesized in the skins of all anurans, the species distribution is sporadic, suggesting that their production may confer some evolutionary advantage to the organism but is not necessary for survival. The low potency of many frog skin antimicrobial peptides is consistent with the hypothesis that cutaneous symbiotic bacteria may provide the major system of defense against pathogenic microorganisms in the environment with antimicrobial peptides assuming a supplementary role in some species.     

Effects of diphenylhydantoin on transport processes in frog skin (Rana ridibunda)

Résumé La diphénylhydantoïne agit sur la face externe de la peau de grenouille en provoquant une augmentation de la différence de potentiel et du courant de court circuit. L'effet est rapide, soutenu et réversible. Des interactions entre DPH, ocytocine, amiloride et amphotéricine B ont été étudiées.     

Central nervous system control of mucous gland secretion from frog skin

Summary Surface electrical stimulation of the diencephalic roof of the frog,Rana berlandieri forreri, brain initiates integumental mucous gland secretion which is abolished by pithing.This study was supported, in part, by U.S. Public Health Service grant AM-16282.     

Inhibition of sodium transport in frog skin by cardiac glycosides of different molecular structure

p 19-OM no- . ; — .     

Appearance of sex hormone receptors in frog (Rana esculenta) tadpole skin during metamorphosis.

In tadpole skin of Rana esculenta, a specific testosterone receptor was detected during the climax in both males and females. The Kass ranged between 1 and 2.79 x 10(9)M-1.     

The effects of Δ-amino-laevulinic acid on sodium and water movement across frog skin

Zusammenfassung -Aminolävulinsäure (ALA) beeinflusst die Passage von Natrium und Wasser durch ein in vitro Präparat der Froschhaut. Dies bestätigt teilweise die Hypothese, dass ALA eine Rolle in gewissen Abnormalitäten der Nierenkanälchen bei akuter klinischer Porphyrie spielt.     

Occurrence of Asn2, Leu5-caerulein in the skin of the african frog Hylambates maculatus

Summary The skin of the African frog, Hylambates maculatus, contains large amounts of a caerulein-like peptide, which has been identified as Asn², Leu⁵-caerulein. The cholecystokinetic activity of Hylambates-caerulein is very similar to that of caerulein.Supported in part by grants from the Consiglio Nazionale delle Ricerche, Roma, Italy.     

Effects of Ag+ on frog skin: Interactions with oxytocin,amiloride and ouabain

Summary Different biological effects of Ag⁺ (10^–4 M) were found depending on its presence in the outer or the inner solution bathing the frog skin. A marked increase in the electrical conductance and an interference with the action of oxytocin and amiloride were found only when Ag⁺ was added to the outer solution. Results suggest that Ag⁺ affects several transport processes, in particular the permeability of the Na entry pathways.This work was supported by the Swiss National Science Foundation, grant No. 1.300.73. We thank Mrs A. Cergneux for skilful secretarial assistance.     

Melanogenesis from tryptophan. Biogenetic experiments with harding-passey mouse melanoma

Riassunto Il triptofano¹⁴C-uniformemente marcato nell'anello benzenico e il triptofano marcato¹⁴C nel metilene sono incorporati in modo significativo nella melanina del melanoma di Harding-Passey del topo.5-ossitriptofano e 5-ossitriptamina non mostrano invece una significativa incorporazione nella stessa melanina. L'incorporazione ottenuta con il triptofano marcato sia nel nucleo che nel metilene è all'incirca uguale a quella ottenuta per somministrazione di tirosina-2-C¹⁴, per cui anche il triptofano deve essere considerato un precursore delle melanine.