ABSTRACT
Primary monolayer cultures of polarized epithelia were derived from single cortical collecting tubules (CCT) of the mammalian kidney (rabbit). The expression of Na-K-ATPase activity (mol 10(-15)/min.cell) and of the transepithelial voltage (VT) in monolayers on membranes was measured in response to defined hormonal supplements of the nephron culture medium (NCM). Hormones were: triiodothyronine (T3; 10(-11) M), dexamethasone (10(-8) M), and aldosterone (10(-9) M). Control was NCM plus fetal calf serum (FCS; 3% v/v). Data are mean (SEM). Na-K-ATPase activity was 10.4 (6.2) in control (n = 27); 18.8 (5.2) in T3 (n = 35); 21.2 (5.5) in dexamethasone (n = 26), and 30.9 (6.5) in aldosterone (n = 24). VT (mV) was 4.2 (3.2) in control (n = 12); 12.7 (3.7) in T3 (n = 12); 16.8 (2.5) in dexamethasone (n = 12), and 28.4 (3.6) in aldosterone (n = 14). Data are evidence that thyroid and corticosteroid hormones selectively induce the postmitotic expression of the sodium carrier activity and other functions related to vectorial solute transport in this polarized epithelium.
