Differentiation of llc-pki cells cultured on native (contractible) collagen gels

The porcine-derived renal epithelial cell line, LLC-PKi, forms a functional epithelium with apical tight junctions and reabsorptive Na+/glucose colransport. In an attempt to further differentiate this epithelium we cultured these cells on contraclible collagen gels. Transepithelial electrical potential difference (PD), resistance (R) and total (It), phloridzin-sensitive (Iphz, 0.18 mM phloridzin), and glucosedependent (Iglc) currents were measured in Ussing chambers. LLCPK₁ cells contracted collagen gels from 32 mm to 22± 0.2 mm in 18 days. Gels were contracted 1 mm/day for the first 10 days then -(1.5 mm/day. Four days after plating confluent monolayers exhibited R = 38.4 ±3.0 fixem², PD = -0.8 ±0.1 mV, I_t = 20.2 ±0.8 /iA/cm2, and IphJ. - 14-1 ±1. μA. Over the next 15 days It and IphJ. increased approximately 5 fold. R decreased -50% between 10 and 11 days after plating, and PD increased -80% between 8 and 9 days and another -50% between 14 and 15 days. 17-19 day old cultures had R = 18.0 ± 0.6 Qxcm², PD = -2.0 ±0.1 niv, 11 = 101.7 ±2.0//A/cm2, Iphz = 69.8 ± 2.4 μA/cm², and Iglc = 88.4 ±1.5 μA/cm². LLC-PKi cells cultured on contractible collagen had transport capabilities far better than those previously observed on non-contractible collagen-coated filters. Electrical characteristics were comparable to those of rat and rabbit proximal tubule in vivo. Supported by NSF.