Effects of ornithine8-oxytocin and ornithine8-vasopressin on the permeability of toad skin

Résumé En employant des crapauds pour doser l'action des peptides sur la perméabilité de la peau, l'effet hydrosmotique de l'arginine⁸-vasotocine s'est montré 200 fois plus puissant que celui de l'ornithine⁸-oxytocine. Ce fait confirme l'importance hydrosmotique de l'acide aminé arginine dans la position 8. Tous 2 ont eu un effet natriférique, mais ce ne fut pas le cas de la lysine⁸-vasopressine et l'ornithine⁸-vasopressine. L'importance natriférique de l'acide aminé isoleucine dans la position 3 en est confirmée.     

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.     

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.     

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.     

The effect of bradykinin on permeability of skin blood vessels

Zusammenfassung Es werden quantitative Vergleiche in 3 Spezies der Hautgefäss-Empfindlichkeit gegenüber Bradykinin und Histamin angestellt.     

Properties of vascular permeability factor in human sera for guinea-pig skin

Summary Properties of vascular permeability factor in native human sera (PF/Nat) showed close similarities with those of necrotizing factor. Time course studies revealed that skin necrosis could be initiated by enhanced vascular permeability.Acknowledgment. The authors wish to thank Prof. H. Hayashi, Kumamoto University for encouragement and discussions.     

Potential toxins of acute liver failure and their effects on blood-brain barrier permeability

The effects of potentials toxins of hepatic coma on the blood-brain barrier (BBB) permeability of the rat have been examined using the Oldendorf technique. Classical toxins of hepatic failure such as ammonia, methyl octanoate, mercaptans, and phenol caused significant increases in BBB permeability. A slight increase in permeability occurred following infusion of peroxidized linoleic acid and unconjugated bilirubin but no increase after infusion of bile acids. E. coli endotoxin infused into rats following partial hepatectomy also increased the BBB permeability.     

Kinetics of increased vascular permeability induced in rat skin by serotonin

Résumé Les auteurs ont étudié la cinétique du passage des complexes protein-colorant à travers les capillaires cutanés dont la perméabilité a été augmentée par l'injection préalable de serotonin dans la peau. Les résultats obtenus ont permis d'établir les lois qui règlent cette cinétique et le rôle des recepteurs adrénergic dans le phenomen inflammatoire.     

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.     

Effect of furosemide on the permeability to Cl of the isolated skin of Leptodactylus ocellatus.

Furosemide added to the Ringer solution bathing the external side of the isolated skin of Leptodactylus ocellatus increased the PD and SCC and inhibited both active chloride influx and passive chloride efflux. The action on chloride permeability is thought to contribute to the diuretic effect of the drug.     

Properties of vascular permeability factor in human sera for guinea-pig skin.

Properties of vascular permeability factor in native human sera (PF/Nat) showed close similarities with those of necrotizing factor. Time course studies revealed that skin necrosis could be initiated by enhanced vascular permeability.     

Morphological effects of serotonin and ketanserin on embryonic chick skin in vitro

Summary Cell and organotypical cultures are used to study the direct effect of serotonin and of ketanserin, a serotonin antagonist, on dermal and epidermal cells of embryonic chick skin. Ketanserin stimulates the increase in cell number and inhibits the differentiation, whereas serotonin stimulates differentiation and inhibits the increase in cell number.     

Morphological effects of serotonin and ketanserin on embryonic chick skin in vitro

Cell and organotypical cultures are used to study the direct effect of serotonin and of ketanserin, a serotonin antagonist, on dermal and epidermal cells of embryonic chick skin. Ketanserin stimulates the increase in cell number and inhibits the differentiation, whereas serotonin stimulates differentiation and inhibits the increase in cell number.     

Similar cytological effects of hydroxylamine and 5-FUDR,agents with different modes of action

Résumé L'hydroxylamine et la 5-fluorodeoxyuridine provoquent des altérations notables dans les chromosomes de méristèmes radiculaires (Vicia etAllium). Ces deux agents empêchent aussi, dans une large mesure la réunion des segments après ruptures des chromosomes. Il est probable que l'hydroxylamine affecte spécifiquement les régions hétérochromatiques.     

Dantrolene: evidence for effects on Na permeability properties of the nodal membrane

The effects of dantrolene on myelinated frog nerve fibers were studied in voltage clamp experiments. Dantrolene shifted the potential-dependent parameters describing Na+ permeability towards more negative membrane potentials. The findings are interpreted as a change in the negative surface charge of the membrane.     

On the nature of some fluorescent substances of pterin type in the adult skin of toad,Bufo vulgaris formosus

Résumé A l'aide de techniques chromatographiques on a pumettre en évidence dans la peau deBufo adulte, outre plus de pigments fluorescents déjà connus, le bufo-chrome donnant de l'acide 2-amino-4-hydroxy-ptéridine-6-carboxylique par oxydation, le bufo-chrome 2 et deux substances à fluorescence jaune, le bufo-yellow 1 spécifique de l'espèceBufo et le bufo-yellow 2 qu'on retrouve chez d'autres amphibiens.