Antibodies against a furosemide binding protein from Ehrlich ascites tumour cells inhibit Na+, K+, Cl- co-transport in frog retinal pigment epithelium.
OBJECTIVE
To investigate whether antibodies against a 100 kDa protein purified by furosemide affinity chromatography from Ehrlich ascites tumour cells could inhibit Na+, K+, Cl- co-transport in the isolated frog retinal pigment epithelium.


METHODS
The rate of Na+, K+, Cl- co-transport across the retinal membrane in the isolated frog RPE preparation was measured as the rate of decrease in the intracellular Cl- activity observed after administration of furosemide in the apical bath. The intracellular Cl- activity was measured with double barrelled Cl- sensitive microelectrodes.


RESULTS
Incubation of frog retinal pigment epithelium for 30 min with antibodies reduced the rate of Na+, K+, Cl- co-transport by 43%, while leaving all other measured electrophysiological parameters intact.


CONCLUSIONS
The antibodies inhibit Na+,K+,Cl- co-transport in the frog retinal pigment epithelium. This could be due to binding of the antibodies to the co-transporter itself or to a regulatory protein.
la Cour
M
M
Eye Department, National University Hospital (Rigshospitalet), Copenhagen, Denmark.
Baekgaard
A
A
Zeuthen
T
T
D000818:Animals; D000906:Antibodies / Q000494:pharmacology*; D002286:Carcinoma, Ehrlich Tumor / Q000378:metabolism* / Q000473:pathology; D002352:Carrier Proteins / Q000037:antagonists & inhibitors* / Q000276:immunology* / Q000378:metabolism; D002712:Chlorides / Q000493:pharmacokinetics; D004594:Electrophysiology; D005665:Furosemide / Q000378:metabolism* / Q000494:pharmacology; D007158:Immunologic Techniques; D010857:Pigment Epithelium of Eye / Q000378:metabolism* / Q000502:physiology; D011892:Rana catesbeiana; D028021:Sodium-Potassium-Chloride Symporters
D000906:Antibodies; D002352:Carrier Proteins; D002712:Chlorides; D028021:Sodium-Potassium-Chloride Symporters; D005665:Furosemide