Acetylcholine and phorbol esters inhibit potassium currents evoked by adenosine and cAMP in Xenopus oocytes.
In Xenopus laevis oocytes, adenosine and other purinergic agonists induce a K+-conductance increase that is fully mimicked by intracellular application of cAMP. Acetylcholine suppresses the K+-conductance increase caused by adenosine, by the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine, or by intracellular injection of cAMP. This effect of acetylcholine is not mimicked by intracellular injection of Ca2+ or of the Ca-mobilizing agent inositol 1,4,5-trisphosphate. However, adenosine and cAMP responses are inhibited by 4 beta-phorbol 12,13-dibutyrate and 4 beta-phorbol 12-myristate 13-acetate. These results suggest that, in Xenopus oocytes, the muscarinic inhibition of purinergic and cAMP responses is mediated through the activation of the phospholipid-dependent, Ca-activated protein kinase (protein kinase C).
Dascal
N
N
Lotan
I
I
Gillo
B
B
Lester
H A
HA
Lass
Y
Y
D000109:Acetylcholine / Q000494:pharmacology*; D000241:Adenosine / Q000037:antagonists & inhibitors*; D000818:Animals; D000242:Cyclic AMP / Q000037:antagonists & inhibitors*; D004553:Electric Conductivity; D005260:Female; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D010703:Phorbol Esters / Q000494:pharmacology*; D010704:Phorbols / Q000494:pharmacology*; D011188:Potassium / Q000502:physiology*; D011493:Protein Kinase C; D011494:Protein Kinases / Q000502:physiology; D011956:Receptors, Cell Surface / Q000187:drug effects; D011983:Receptors, Purinergic; D014982:Xenopus laevis
D010703:Phorbol Esters; D010704:Phorbols; D011956:Receptors, Cell Surface; D011983:Receptors, Purinergic; D000242:Cyclic AMP; D011494:Protein Kinases; D011493:Protein Kinase C; D000241:Adenosine; D000109:Acetylcholine; D011188:Potassium