P. Gomes et al., Ouabain-insensitive acidification by dopamine in renal OK cells: primary control of the Na+/H+ exchanger, AM J P-REG, 281(1), 2001, pp. R10-R18
Citations number
41
Categorie Soggetti
Physiology
Journal title
AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY
The present study was aimed at evaluating the role of D-1- and D-2-like rec
eptors and investigating whether inhibition of Na+ transepithelial flux by
dopamine is primarily dependent on inhibition of the apical Na+/H+ exchange
r, inhibition of the basolateral Na+-K(+)ATPase, or both. The data presente
d here show that opossum kidney cells are endowed with D-1- and D-2-like re
ceptors, the activation of the former, but not the latter, accompanied by s
timulation of adenylyl cyclase (EC50 =220 +/- 2 nM), marked intracellular a
cidification (IC50 = 58 +/- 2 nM), and attenuation of amphotericin B-induce
d decreases in short-circuit current (28.6 +/- 4.5% reduction) without affe
cting intracellular pH recovery after CO2 removal. These results agree with
the view that dopamine, through the activation of D-1- but not D-2-like re
ceptors, inhibits both the Na+/H+ exchanger (0.001933 +/- 0.000121 vs. 0.00
0887 +/- 0.000073 pH unit/s) and Na+-K+-ATPase without interfering with the
Na+ independent HCO3- transporter. It is concluded that dopamine, through
the action of D-1- like receptors, inhibits both the Na+/H+ exchanger and N
a+-K+-ATPase, but its marked acidifying effects result from inhibition of t
he Na+/H+ exchanger only, without interfering with the Na+-independent HCO3
- transporter and Na+-K+-ATPase.