K activity of CCD principal cells from normal and DOCA-treated rabbits.
We used liquid ion exchanger and conventional microelectrodes to evaluate the effects of mineralocorticoids on the intracellular K activity (aiK) and K transport properties of principal cells (PC) of isolated cortical collecting ducts (CCDs). Hoffman modulation optics and electrophysiological methods were used to identify PC. K activity was measured with two single-barreled electrodes. We found that aiK of PC from deoxycorticosterone acetate (DOCA)-treated rabbits (97.6 mM) was not different from controls (94.8 mM). The driving forces for K transport across the basolateral membrane favored cell to bath (reabsorption) in PCs from controls and bath to cell (secretion) in PCs from DOCA-treated rabbits. However, the driving force for K secretion across the apical membrane was not significantly different between the two groups. We used the intracellular aiKs and bath ion substitutions (gluconate for Cl and K for Na) to evaluate the effects of DOCA on the ion-selective properties of the basolateral membrane of PC. DOCA increased PK/PCl from 0.33 to 0.89. Our conclusion was as follows: in PC of control rabbits K is above electrochemical equilibrium across the basolateral membrane. However, the basolateral K conductance is probably too small for significant K recycling. In PC of DOCA-treated rabbits the aiK is below electrochemical equilibrium across the basolateral membrane and the K conductance is increased. These effects enhance K secretion across this border while maintaining cell K constant.
Sansom
S C
SC
Department of Physiology, Yale University School of Medicine, New Haven, Connecticut 06510.
Agulian
S
S
Muto
S
S
Illig
V
V
Giebisch
G
G
D000465:Algorithms; D000818:Animals; D003900:Desoxycorticosterone / Q000494:pharmacology*; D005260:Female; D007684:Kidney Tubules / Q000378:metabolism*; D007685:Kidney Tubules, Collecting / Q000187:drug effects / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D011817:Rabbits
D003900:Desoxycorticosterone; D011188:Potassium