Further electrophysiological characterization of the alpha- and beta-intercalated cells along the rabbit distal nephron segments: effects of inhibitors.

To further characterize the alpha- and beta-intercalated cells (alpha-IC, beta-IC) in the isolated and perfused connecting tubule (CNT), cortical collecting duct (CCD) and outer medullary collecting duct in the inner stripe (OMCDi) of rabbit kidneys, we studied the effects of various transport inhibitors on electrical parameters. They included inhibitors of Cl-/HCO3- exchanger (4-acetamino-4'-isothiocyanostilbene-2,2'-disulfonic acid, SITS), carbonic anhydrase (acetazolamide) and Na(+)-K(+)-ATPase (ouabain). Upon addition of 10(-3) M SITS to the bath, the basolateral membrane voltage (VB) of alpha-IC in the OMCDi and CCD was significantly hyperpolarized by 20.8 +/- 4.6 (n = 5) and 29.8 +/- 5.6 mV (n = 11), respectively. On the other hand, luminal addition of SITS had no effects on VB of alpha-IC in the OMCDi and CCD. Neither bath nor lumen SITS affected VB of beta-IC in the CCD and CNT. When 10(-4) M acetazolamide was added to the bath, VB of alpha-IC in the OMCDi and CCD was significantly hyperpolarized by 20.0 +/- 4.1 (n = 4) and 18.6 +/- 1.7 mV (n = 3), respectively. Similarly, 10(-4) M acetazolamide in the bath caused the basolateral membrane of beta-IC in the CCD and CNT to hyperpolarize significantly by 34.3 +/- 7.9 (n = 6) and 21.6 +/- 2.9 mV (n = 3), respectively. Luminal addition of acetazolamide had no effect on VB of alpha-IC in the CCD and OMCDi and beta-IC in the CCD and CNT.(ABSTRACT TRUNCATED AT 250 WORDS)