Cyclic AMP effects on chloride transport and carbonic anhydrase activity in frog skin

1990 ◽  
Vol 68 (9) ◽  
pp. 1269-1274 ◽  
Author(s):  
Ignacio Galar ◽  
Ma. del Carmen Marroquin
Keyword(s):  
Carbonic Anhydrase ◽  
Chloride Solution ◽  
Frog Skin ◽  
Prolonged Exposure ◽  
Freezing Point ◽  
Chloride Transport ◽  
Carbonic Anhydrase Activity ◽  
Unidirectional Flux ◽  
Frog Skin Epithelium ◽  
Chloride Influx

Unidirectional (36Cl) chloride fluxes across isolated and short-circuited frog skin were measured, with both sides bathed in low chloride solution. Transepithelial chloride influx was inhibited by exogenous cAMP as well as by substances enhancing its cellular concentration, such as epinephrine, isoproterenol, and 3-isobutyl-1-methylxanthine (IBMX). Epinephrine and isoproterenol addition resulted in an increase of transepithelial chloride outflux, but exogenous cAMP or IBMX had no significant effect on this unidirectional flux. Phenylephrine had no significant effect on influx or outflux. Carbonic anhydrase (CA) activity in extracts obtained from frog skin epithelium was inhibited by pretreatment with IBMX at 4–5 °C and prolonged exposure to cAMP at freezing point. cAMP or IBMX alone had no significant effects on CA activity. This catalytic activity was chloride insensitive and was abolished by 0.1 μM. acetazolamide. Results suggest a [Formula: see text] exchange inhibition by cAMP via carbonic anhydrase inactivation. Chloride outflux stimulation by β-adrenergic agonists does not seem to depend solely on an increase in cAMP concentration.Key words: frog skin, chloride transport, exogenous and induced cAMP effects, carbonic anhydrase inhibition.

Salt transport across isolated frog skin

1971 ◽  
Vol 262 (842) ◽  
pp. 153-161 ◽  
Keyword(s):  
Sodium Transport ◽  
Frog Skin ◽  
Chloride Transport ◽  
Ruthenium Red ◽  
Salt Transport ◽  
Skin Epithelium ◽  
Frog Skin Epithelium ◽  
Ionic Lanthanum ◽  
And Function ◽  
The Relationship

We have measured on isolated epithelia of Rana skin the amount of tissue sodium that equilibrates with the sodium present in the solution in contact with the outside surface. Only about 12 % of the sodium in the tissue equilibrated with outside sodium. Antidiuretic hormone (0.1 u/ml) and ouabain (10 -4 mol l -1 ) had no effect on the amount of cell sodium that equilibrated with outside sodium. We have also studied with the electron microscope the localization of the permeability barriers of frog skin epithelium using as tracers ruthenium red and colloidal and ionic lanthanum. Our observations indicate that there are two barriers to diffusion in frog skin epithelium. The first is at the s. corneum, the second at the s. granulosum. Of these, the first is the least selective. In other experiments the effects of acetazolamide and amiloride on active transport of both sodium and chloride were determined. Acetazolamide (10 -4 mol l -1 ) blocked chloride transport without affecting sodium transport. Amiloride (10-4 mol l-1) blocked sodium transport and did not modify chloride transport. These results and others available in the literature are used to raise some defined questions on the relationship between structure and function and the coupling of ion fluxes in frog skin.

Sodium and chloride transport across rabbit ileal brush border. II. Evidence for Cl-HCO3 exchange and mechanism of coupling

1985 ◽  
Vol 249 (2) ◽  
pp. G236-G245 ◽  
Author(s):  
R. Knickelbein ◽  
P. S. Aronson ◽  
C. M. Schron ◽  
J. Seifter ◽  
J. W. Dobbins
Keyword(s):  
Carbonic Anhydrase ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Chloride Transport ◽  
Carbonic Anhydrase Activity ◽  
Ph Gradient ◽  
Rabbit Ileum ◽  
Cl Transport ◽  
Internal Buffer ◽  
Na Uptake

An inside-alkaline pH gradient (pH 7.7 inside, 5.5 outside) stimulated Cl uptake in brush-border vesicles from rabbit ileum. The addition of HCO3 without changing the pH gradient further stimulated Cl uptake to a level fourfold greater than equilibrated Cl uptake. Although a K diffusion potential stimulated Cl uptake, this was insensitive to inhibition by 4,4-diisothiocyanostilbene-2,2'-disulfonate (DIDS), whereas pH and HCO3 gradient-stimulated Cl uptake was inhibited by DIDS. pH and HCO3 gradient-stimulated Cl uptake was found to be a saturable function of the Cl concentration with a Km of 3.5 mM and a Vmax of 49 nmol X mg prot-1 X min-1. To distinguish between coupling of Na and Cl transport by cotransport or dual exchange (Na-H and Cl-HCO3 exchange), we determined uptake with high (134 mM Tris-HEPES-MES) internal buffer and low (1.34 mM Tris-HEPES-MES) internal buffer concentrations. Inwardly directed gradients of 50 mM Na, 50 mM K, or 50 mM Na and K did not stimulate Cl uptake, and 50 mM Cl, 50 mM K, or 50 mM KCl did not stimulate Na uptake, with high internal buffer, excluding cotransport. In contrast, 50 mM Na stimulated Cl uptake (inhibited by 1 mM DIDS) and 50 mM Cl stimulated Na uptake (inhibited by 1 mM amiloride) in low buffer media. To determine a role for carbonic anhydrase, Na-stimulated Cl uptake was determined in low buffer media, equilibrated with either 100% N2 or 95% N2-5% CO2. Na stimulated Cl uptake 80% (compared with trimethylammonium control) with CO2 but only 30% with N2 (P less than 0.05). Acetazolamide partially inhibited (P less than 0.025) the stimulation of Cl uptake with CO2 but not with N2. Carbonic anhydrase activity was measured in homogenate and brush-border membrane and was enriched 7.9 +/- 0.4-fold, whereas sucrase was enriched 14.0 +/- 1.1-fold. We conclude that coupled Na and Cl transport occurs by dual exchange (Na-H and Cl-HCO3) and carbonic anhydrase, apparently located on the brush-border membrane, facilitates dual exchange by providing HCO3.

1123: Renal Oxalate Transport Depends on Local Carbonic Anhydrase Activity in the Proximal Tubule

2004 ◽  
Vol 171 (4S) ◽  
pp. 296-296
Author(s):  
Michael Straub ◽  
Joséphine Befolo-Elo ◽  
Richard E Hautmann ◽  
Edgar Braendle
Keyword(s):  
Carbonic Anhydrase ◽  
Proximal Tubule ◽  
Carbonic Anhydrase Activity ◽  
Oxalate Transport

The Sigma-1 Receptor Ligands Chlorpromazine and Trifluoperazine Inhibit Na+ Transport in Frog Skin Epithelium

BIOPHYSICS ◽  
2020 ◽  
Vol 65 (5) ◽  
pp. 784-787
Author(s):  
A. V. Melnitskaya ◽  
Z. I. Krutetskaya ◽  
V. G. Antonov ◽  
N. I. Krutetskaya
Keyword(s):  
Frog Skin ◽  
Receptor Ligands ◽  
Na Transport ◽  
Sigma 1 Receptor ◽  
Skin Epithelium ◽  
Frog Skin Epithelium ◽  
Sigma 1
Sign in / Sign up

Export Citation Format

Share Document