Elevation of intracellular calcium by muscarinic receptor activation induces a block of voltage-activated rat ether-à-go-go channels in a stably transfected cell line.
We have studied the properties of r-eag voltage-activated potassium channels in a stably transfected human embryonic kidney cell line. It was found that r-eag channels are rapidly and reversibly inhibited by a rise in intracellular calcium from 30 to 300 nM. The inhibition does not appear to depend on the activity of calcium-dependent kinases and phosphatases. The effect of calcium on r-eag channel activity was studied in inside-out membrane patches. Calcium inhibited r-eag channel activity with a mean IC50 of 67 nM. Activation of muscarinic receptors, generating calcium oscillations in the transfected cells, induced a synchronous inhibition of r-eag mediated outward currents. This shows that calcium can mediate r-eag current inhibition following muscarinic receptor activation. The data indicate that r-eag channels are calcium-inhibitable voltage-activated potassium channels.
Stansfeld
C E
CE
Zentrum für Moleculare Neurobiologie, Universität Hamburg, Germany.
Röper
J
J
Ludwig
J
J
Weseloh
R M
RM
Marsh
S J
SJ
Brown
D A
DA
Pongs
O
O
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D004594:Electrophysiology; D051638:Ether-A-Go-Go Potassium Channels; D006801:Humans; D015759:Ionomycin / Q000494:pharmacology; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D015221:Potassium Channels / Q000378:metabolism; D051381:Rats; D011976:Receptors, Muscarinic / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D014162:Transfection
D051638:Ether-A-Go-Go Potassium Channels; D015221:Potassium Channels; D011976:Receptors, Muscarinic; D015759:Ionomycin; D002118:Calcium