title: An anticalmodulin drug, W-7, inhibits the voltage-dependent calcium current in Paramecium caudatum.
abstract: The anticalmodulin drug, W-7 [N-(6 aminohexyl)-5-chloro-1-naphthalenesulphonamide] specifically inhibits the voltage-dependent Ca-current of Paramecium as well as the behavioural consequence of Ca2+ influx, backward swimming. The dechlorinated analogue, W-5, is four to five times less effective. Analysis of membrane currents under voltage clamp shows that W-7 not only reversibly inhibits the voltage-dependent Ca-current but also shifts the voltage sensitivity of this Ca-current towards less negative voltages in a concentration-dependent manner. We suggest that Paramecium can be used as a system to screen behaviourally for other Ca-channel blockers as well as to study the mechanism of action of these drugs.
mesh_terms: D000818:Animals; D002118:Calcium / Q000502:physiology*; D002147:Calmodulin / Q000037:antagonists & inhibitors*; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D008124:Locomotion / Q000187:drug effects; D008564:Membrane Potentials; D010247:Paramecium / Q000187:drug effects*; D013449:Sulfonamides / Q000494:pharmacology*
chemical_list: D002147:Calmodulin; D013449:Sulfonamides; C017967:W 7; D002118:Calcium