Cyclic AMP-dependent regulation of P-type calcium channels expressed in Xenopus oocytes.
Xenopus oocytes injected with rat cerebellum mRNA, express voltage-dependent calcium channels (VDCC). These were identified as P-type Ca2+ channels by their insensitivity to dihydropyridines and omega-conotoxin and by their blockade by Agelenopsis aperta venom (containing the funnel-web spider toxins: FTX and omega-Aga-IV-A). Coinjection of cerebellar mRNA and antisense oligonucleotide complementary to the dihydropyridine-resistant brain Ca2+ channel, named BI [Mori Y. et al. (1991) Nature 350:398-402] or rbA [Starr T. V. B. et al. (1991) Proc Natl Acad Sci USA 88:5621-5625], strongly reduced the expressed Ba2+ current suggesting that these clones encode a P-type VDCC. The macroscopic Ca2+ channel activity was increased by direct intraoocyte injection of cAMP. This increase in current amplitude was concomitant with a slowing of current inactivation, and was attributed to activation of protein kinase A, since it could be antagonized by a peptidic inhibitor of this enzyme. Positive regulation of P-type VDCC could be of importance in Purkinje neurons and motor nerve terminals where this channel is predominant.
Fournier
F
F
CRBM-C.N.R.S. UPR 9008, I.N.S.E.R.M. U249, Montpellier, France.
Bourinet
E
E
Nargeot
J
J
Charnet
P
P
D000818:Animals; D001464:Barium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D002531:Cerebellum / Q000737:chemistry; D000242:Cyclic AMP / Q000494:pharmacology*; D004594:Electrophysiology; D004789:Enzyme Activation; D005260:Female; D016376:Oligonucleotides, Antisense; D009865:Oocytes / Q000378:metabolism*; D010766:Phosphorylation; D011073:Polyamines / Q000494:pharmacology; D011494:Protein Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D013111:Spider Venoms / Q000494:pharmacology; D014162:Transfection; D014982:Xenopus laevis; D020867:omega-Agatoxin IVA
D002121:Calcium Channel Blockers; D015220:Calcium Channels; C071920:FTX, spider toxin; D016376:Oligonucleotides, Antisense; D011073:Polyamines; D012333:RNA, Messenger; D013111:Spider Venoms; D020867:omega-Agatoxin IVA; D001464:Barium; D000242:Cyclic AMP; D011494:Protein Kinases