We performed Ussing chamber experiments on cultured human bronchial epithelial cells to look for the presence of electrogenic dibasic amino acid transport. Apical but not basolateral L-arginine (10-1, 000 microM) increased the short-circuit current. Maximal effect and EC50 were approximately 3.5 microA/cm2 and 80 microM, respectively, in cells from normal subjects and cystic fibrosis patients. The involvement of nitric oxide was ruled out because a nitric oxide synthase inhibitor (NG-nitro-L-arginine methyl ester) did not decrease the arginine-dependent current. Apical L-lysine, L-alanine, and L-proline, but not aspartic acid, were also effective in increasing the short-circuit current, with EC50 values ranging from 26 to 971 microM. Experiments performed with radiolabeled arginine demonstrated the presence of an Na+-dependent concentrative transporter on the apical membrane of bronchial cells. This transporter could be important in vivo to maintain a low amino acid concentration in the fluid covering the airway surface.
An electrogenic amino acid transporter in the apical membrane of cultured human bronchial epithelial cells / Galietta, L J; Musante, L; Romio, L; Caruso, U; Fantasia, Francesca; Gazzolo, A; Romano, L; Sacco, O; Rossi, G A; Varesio, L; Zegarra-Moran, O. - In: AMERICAN JOURNAL OF PHYSIOLOGY. - ISSN 0002-9513. - 275:5 Pt 1(1998), p. L917-23.
An electrogenic amino acid transporter in the apical membrane of cultured human bronchial epithelial cells
Galietta, L J;FANTASIA, FRANCESCA;
1998
Abstract
We performed Ussing chamber experiments on cultured human bronchial epithelial cells to look for the presence of electrogenic dibasic amino acid transport. Apical but not basolateral L-arginine (10-1, 000 microM) increased the short-circuit current. Maximal effect and EC50 were approximately 3.5 microA/cm2 and 80 microM, respectively, in cells from normal subjects and cystic fibrosis patients. The involvement of nitric oxide was ruled out because a nitric oxide synthase inhibitor (NG-nitro-L-arginine methyl ester) did not decrease the arginine-dependent current. Apical L-lysine, L-alanine, and L-proline, but not aspartic acid, were also effective in increasing the short-circuit current, with EC50 values ranging from 26 to 971 microM. Experiments performed with radiolabeled arginine demonstrated the presence of an Na+-dependent concentrative transporter on the apical membrane of bronchial cells. This transporter could be important in vivo to maintain a low amino acid concentration in the fluid covering the airway surface.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.