Different effects of baclofen and GTP gamma S on voltage-activated Ca2+ currents in rat hippocampal neurons in vitro.
Reduction of voltage-activated Ca2+ currents by intracellular application of guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) through ultraviolet (UV) photolysis of the caged compound, is followed by a re-augmentation to control levels within 10 min, independently of the divalent cation used. The Ca2+ current inhibition by the gamma-aminobutyric acid type B (GABAB) receptor agonist baclofen, which is also thought to be mediated by a GTP-binding protein (G-protein), is potentiated when GTP gamma S is uncaged during agonist superfusion. The authors suggest that GTP gamma S activates G-protein-dependent pathways that are not activated by the baclofen receptor.
Frank
C
C
Department of Pharmacology, Istituto Superiore di Sanitá, Rome, Italy. frank@irmiss.bitnet.it
Engert
F
F
Tokutomi
N
N
Lux
H D
HD
D000818:Animals; D001418:Baclofen / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology*; D006624:Hippocampus / Q000187:drug effects*; D066298:In Vitro Techniques; D007700:Kinetics; D051381:Rats
D015220:Calcium Channels; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D001418:Baclofen