Nootropic agent vinpocetine blocks delayed rectified potassium currents more strongly than high-threshold calcium currents.
A two-microelectrode potential clamping method was used on isolated common snail neurons to measure high-threshold Ca2+ and delayed rectified K+ currents. Addition of the nootropic agent vinpocetine (VPC) to the bathing solution rapidly and reversibly inhibited both types of current. The effects of VPC were dose-dependent and were independent of the test stimulus voltage. Maximum blockade of the Ca2+ current averaged 27% at a VPC concentration of 600 microM. Maximum blockade of the K+ current averaged 76% at a VPC concentration of 30 microM. It is concluded that K+ channels are more likely targets of VPC than Ca2+ channels.
Bukanova YuV
Science Research Institute of the Brain, Russian Academy, Medical Sciences, Moscow.
Solntseva
E I
EI
D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D004594:Electrophysiology; D006372:Helix, Snails / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D018697:Nootropic Agents / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers; D014748:Vinca Alkaloids / Q000494:pharmacology*
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D018697:Nootropic Agents; D026902:Potassium Channel Blockers; D014748:Vinca Alkaloids; C013983:vinpocetine