ISSN:
1432-2013
Schlagwort(e):
Nifedipine
;
Ca2+ channels
;
Acetylcholine release
;
Synapse
;
Aplysia
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Medizin
Notizen:
Abstract The effects of the dihydropyridine (DHP) Ca2+ channel antagonist, nifedipine, were studied on the cholinergic synapse between the presynaptic neurones B4/B5 and the postsynaptic neurones B3/B6 located in the buccal ganglion of Aplysia californica. Nifedipine (10 μM) decreased the presynaptic Ca2+ current by 30%–40%. Blockade of DHP-sensitive Ca2+ channels, however, did not affect quantal transmitter release from the presynaptic neurones. Thus, at this synapse, DHP-sensitive Ca2+ channels appear not to be involved in acetylcholine (ACh) release. The postsynaptic response to an ionophoretic application of ACh was decreased by nifedipine, pointing to a blocking action of the drug on the postsynaptic receptor/channel complex. Nifedipine was also found to activate protein kinase C, which in turn induces an increase in the nifedipine-resistant presynaptic Ca2+ influx and in the number of released ACh quanta. These effects of nifedipine could be prevented by a previous application of 1, 5-(isoquinolinylsulfonyl)-2-methyl-piperazine (H-7), a protein kinase blocker.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00370420
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