Modulation of Na/K-ATPase activity by isoproterenol and propranolol in human non-pigmented ciliary epithelial cells.
OBJECTIVE
The present study investigates whether beta-adrenoreceptor agents such as isoproterenol and propranolol can regulate Na(+)-K(+)-ATPase activity in cultured human non-pigmented ciliary epithelial cells.


METHODS
Human non-pigmented ciliary epithelial cells (ODM2) were grown to confluence. The active ion transport mediated by the Na(+)-K(+)-ATPase was evaluated by measuring ouabain-sensitive rubidium (Rb+) uptake. In a first set of experiments, cells were exposed to the beta-adrenoreceptor agonist isoproterenol (0.01-10 microM). In a second set of experiments, cells were exposed to isoproterenol (1 microM) in the presence of different concentrations of the beta-adrenoreceptor antagonist propranolol (0.01, 0.1, 1 microM).


RESULTS
In a concentration-dependent manner, isoproterenol induced an increase in Na(+)-K(+)-ATPase activity. The maximal Na(+)-K(+)-ATPase activity was observed at a concentration of 1 microM of isoproterenol (283 +/- 58%, P < 0.001). The increase in Na(+)-K(+)-ATPase activity evoked by isoproterenol (1 microM) was inhibited. In a concentration dependent manner, by propranolol (maximum: 659 +/- 39 vs. 141 +/- 42 pM/mg protein/min, P < 0.01).


CONCLUSIONS
The beta-adrenoreceptor agents isoproterenol and propranolol are apparently able to modulate Na(+)-K(+)-ATPase activity in cultured human non-pigmented ciliary epithelial cells.
Liu
R
R
Laboratory of Ocular Pharmacology and Physiology, University Eye Clinic, Mittlere Strasse 91, PO Box, CH-4012 Basel.
Hintermann
E
E
Erb
C
C
Tanner
H
H
Flammer
J
J
Eberle
A N
AN
Haefliger
I O
IO
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D002461:Cell Line, Transformed; D002478:Cells, Cultured; D002924:Ciliary Body / Q000201:enzymology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology*; D010857:Pigment Epithelium of Eye / Q000201:enzymology*; D011433:Propranolol / Q000494:pharmacology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D011433:Propranolol; D000254:Sodium-Potassium-Exchanging ATPase; D007545:Isoproterenol