ABSTRACT
The mammalian cortical collecting duct (CCD) plays a major role in regulating renal NaCl reabsorption, which is important in Na+ and Cl- homeostasis. The M-1 cell line, derived from the mouse cortical collecting duct, has been used as a mammalian model of the study on the electrolytes transport in CCD. M-1 cells were grown on collagen-coated permeable support and short circuit current (Isc) was measured. M-1 cells developed amiloride-sensitive current 5apprx7 days after seeding. Apical and basolateral addition of ATP induced increase in Isc in M-1 cells, which was partly retained in Na+/-free or Cl--free solution, indicating that ATP increased Na+ absorption and Cl- secretion in M-1 cells. Cl- secretion was mediated by the activation of apical cystic fibrosis transmembrane regulator (CFTR) chloride channels and Ca2+/-activated chloride channels, but Na+ absorption was not mediated by activation of epithelal sodium channel (ENaC). ATP increased cAMP content in M-1 cells. The RT-PCR analysis demonstrated that M-1 cells express P2Y2, P2X3 and P2Y4 receptors. These results showed that ATP regulates Na+ and Cl- transports via multiple P2 purinoceptors on the apical and basolateral membranes in M-1 cells.