cAMP-activated C1 conductance is expressed in Xenopus oocytes by injection of shark rectal gland mRNA.
Development of reliable expression systems for use in identification and functional characterization of proteins required for secretory Cl channel activity is key to understanding the molecular basis of cystic fibrosis (CF). Until now, heterologous expression of epithelial Cl channels had not been accomplished. We show here that Xenopus oocytes express an adenosine 3',5'-cyclic monophosphate (cAMP)-activated Cl conductance after injection of mRNA from shark rectal gland. Current through this conductance was rapidly activated by intracellular application of cAMP, reversed near the chloride equilibrium potential (ECl), blocked by the Cl channel inhibitor 5-nitro-2-(3-phenylpropylamino) benzoate, and was not affected by preincubation with the intracellular calcium buffer bis-(2-amino-5-methylphenoxy)-ethane-N,N,N',N'-tetraacetic acid tetraacetoxymethyl ester, a condition that prohibits activation of the endogenous Ca-activated Cl conductance.
Sullivan
S K
SK
Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York 10032.
Swamy
K
K
Field
M
M
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D018118:Chloride Channels; D002712:Chlorides / Q000378:metabolism*; D000242:Cyclic AMP / Q000494:pharmacology*; D005260:Female; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D007700:Kinetics; D008564:Membrane Potentials; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics*; D012491:Salt Gland / Q000502:physiology*; D012754:Sharks; D013997:Time Factors; D014982:Xenopus laevis
D018118:Chloride Channels; D002712:Chlorides; D007473:Ion Channels; D008565:Membrane Proteins; D012333:RNA, Messenger; D000001:Calcimycin; D000242:Cyclic AMP; D002118:Calcium