Electrophysiological identification of principal and intercalated cells in the rabbit outer medullary collecting duct

Intracellular microelectrode techniques were used together with inhibitors of Na+ transport (amiloride) and H+ transport (acetazolamide and SITS) to identify principal cells and intercalated cells in the outer stripe of the rabbit outer medullary collecting duct. The principal cell (n = 9) had a basolateral membrane voltage (Vbl) of -64.7 +/- 3.2 mV, a fractional resistance of the apical membrane (fRa = Ra/Ra + Rbl) of 0.82 +/- 0.02, and a K+-selective basolateral membrane. Luminal amiloride hyperpolarized Vbl by 10.3 +/- 2.1 mV and increased fRa to near unity (n = 7). Bath acetazolamide and SITS were without effect on these parameters. The intercalated cell (n = 5) had a Vbl of -25.0 +/- 3.2 mV, a fRa of 0.99 +/- 0.01, and a Cl(-)-selective basolateral membrane. Bath acetazolamide or SITS hyperpolarized Vbl by 26.4 +/- 8.2 mV. Luminal amiloride did not alter Vbl of this cell. The differential effects of the inhibitors also indicate that the principal and intercalated cells are probably not directly coupled electrically.