Inhibitory action of acetylcholine, baclofen and GTP-gamma-S on calcium channels in adult rat sensory neurons.
High- and low-voltage activated calcium channel currents (HVA and LVA) were inhibited by acetylcholine (10-100 microM) and baclofen (10 microM) in adult rat sensory neurons. This modulatory effect was present on dihydropyridine (nifedipine 1 microM) and/or omega-conotoxin (3.2 microM, 2-5 h incubation) insensitive components and was insensitive to holding potentials (Vh -50 to -90 mV). GTP-gamma-S (100 microM) prolonged calcium channel current activation in a time- and voltage-dependent manner. On the other hand, the current amplitude reduction induced by muscarinic and GABAB receptor activation, was not relieved by a 50-ms conditioning prepulse to +50 mV. This suggests the possibility of an alternative voltage-independent modulation mechanism.
Formenti
A
A
Institute of Human Physiology II, Milan, Italy.
Sansone
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V
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D001418:Baclofen / Q000494:pharmacology*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D004594:Electrophysiology; D005727:Ganglia, Spinal / Q000166:cytology / Q000187:drug effects; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology*; D006719:Homovanillic Acid / Q000378:metabolism; D009475:Neurons, Afferent / Q000187:drug effects*; D010456:Peptides, Cyclic / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D020960:omega-Conotoxins
D002121:Calcium Channel Blockers; D010456:Peptides, Cyclic; D020960:omega-Conotoxins; C053423:Conus magus toxin; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D001418:Baclofen; D000109:Acetylcholine; D006719:Homovanillic Acid