Activators of protein kinase C and phenylephrine depolarize the astrocyte membrane by reducing the K+ permeability.
The membrane potential of astrocytes has been measured by monitoring the absorbance of a cyanine dye DiS-C2-(5). Ba2+, the phorbol ester 12-tetradecanoylphorbol myristateacetate (TPA) and the diglyceride, dioctanoylglycerol (DiC8) depolarize the membrane. Valinomycin which makes the membrane potential dependent on the K+ electrochemical potential evokes a hyperpolarization when added subsequently. The alpha-adrenergic receptor agonist phenylephrine was blocked by Ba2+, TPA, DiC8 and valinomycin. The results suggest that a protein kinase C-mediated reduction in the K+ permeability is responsible for the depolarizing effect of TPA, DiC8 and phenylephrine.
Akerman
K E
KE
Abo Akademi, Department of Biochemistry and Pharmacy, Finland.
Enkvist
M O
MO
Holopainen
I
I
D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D002478:Cells, Cultured; D004075:Diglycerides / Q000494:pharmacology; D004225:Dithiazanine; D010656:Phenylephrine / Q000378:metabolism / Q000502:physiology*; D011188:Potassium / Q000378:metabolism / Q000502:physiology*; D011493:Protein Kinase C / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D004075:Diglycerides; C044295:1,2-dioctanoylglycerol; D010656:Phenylephrine; D004225:Dithiazanine; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D011188:Potassium