ATRIAL NATRIURETIC FACTOR AND cGMP INHIBIT AMILORIDE-SENSITIVE NA + TRANSPORT IN THE CULTURED RENAL EPITHELIAL CELL LINE, LLC-PK I

HORACIO F. CANTIELLO AND DENNIS A. AUSIELLO

BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS

Año: 1986 p. 852 - 860

0006-291X

The renal cell culture model, LLC-PK., which contains an amiloride-sensltlve conductlve Na transport pathway and a Na /H exchanger, was utilized to examine the direct effects of atriopeptin II and cGMP on Na transport in eplthellal cells. Exposure of cells to atriopeptin II (10 -7 M) increased cGMP production within 2 min of addition to cells in monolayer. Atriopeptin II (10 -7 M) or exogenous 8-bromo-cGMP (10 -3 M) maximally inhibited the uptake of 22Na+ through the conductive pathway which accounted for up to 60% of total 22Na + uptake. The apparent K. for this inhibition by atriopeptin II was 2 x 10 -11M. Amiloride i~hibited 22Na + uptake to a similar extent as atriopeptin II, and the effects of the presence of both agents was not additive. In contrast, neither atriopeptin II nor cGMP blunted the increment in 22Na + uptake + induced by a pH gradient. Thus atriopeptin II can directly inhibit Na transport in renal epithelial cells, probably through its stimulation of cGMP.