PROPERTIES OF A CL- CONDUCTIVE PATHWAY(S) IN MICROSOMES FROM RAT-KIDNEY INNER MEDULLA - INVOLVEMENT OF CYSTIC-FIBROSIS TRANSMEMBRANE REGULATOR PROTEIN

The properties of a protein-kinase-A(PKA)-activated Cl--conductive pat hway(s) in alkaline phosphatase-enriched microsomes from the rat inner medulla (IMV) were investigated. Transcripts of cystic fibrosis trans membrane regulator (CFTR) were detected by reverse transcription/polym erase analysis of total RNA from tile inner medullar while immunoblot analysis using anti-CFTR antibodies detected a 170-kDa protein in the IMV. The PKA Cl--conductive pathway(s) was studied by measuring the ra te of valinomycin-induced microsomal swelling by light scattering, PKA increased the rate of valinomycin-induced swelling of vesicles consis tent with the presence of Cl--conductive pathway(s). The pharmacologic al properties and anion selectivity of the PKA-activated Cl--conductiv e pathway(s) were similar to those of the CFTR Cl- channel. Our result s show that a CFTR Cl- channel and possibly another cAMP-activated pat hway(s) may participate in Cl- secretion in the rat inner medulla.