Inhibition of calcium channels in rat hippocampal CA1 neurons by conantokin-T.
Effects of conantokin-T, a 21 amino acid peptide toxin isolated from the fish-hunting cone snail Conus tulipa, on the high-voltage-activated Ca2+ channel currents were studied in acutely dissociated rat hippocampal CA1 neurons using whole-cell voltage clamp-recording technique with 5 mM Ba2+ as the charge carrier. Conantokin-T inhibited the whole-cell Ba2+ current (IBa) in a concentration-dependent manner. The nimodipine (20 microM) and omega-agatoxin-IVA (0.2 microM) block of IBa were abolished in the presence of conantokin-T (3 microM); however, conantokin-T (3 microM) did not affect the block of IBa induced by 3 microM omega-conotoxin-GVIA. These results indicate that conantokin-T is a potent but wide-spectrum Ca2+ channel antagonist.
Hsu
K S
KS
Department of Pharmacology, College of Medicine, National Cheng-Kung University, Tainan, Taiwan, ROC. richard@ncku.edu.tw
Huang
C C
CC
Lyu
P C
PC
D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020916:Conotoxins; D006624:Hippocampus / Q000166:cytology / Q000502:physiology*; D036341:Intercellular Signaling Peptides and Proteins; D008564:Membrane Potentials / Q000502:physiology*; D008978:Mollusk Venoms / Q000494:pharmacology*; D009553:Nimodipine / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020866:omega-Conotoxin GVIA
D002121:Calcium Channel Blockers; D020916:Conotoxins; D036341:Intercellular Signaling Peptides and Proteins; D008978:Mollusk Venoms; D010455:Peptides; C063571:conantokin-T; D009553:Nimodipine; D020866:omega-Conotoxin GVIA