Effect of avermectins on Ca2+-dependent Cl- currents in plasmalemma of Chara corallina cells.
A natural complex of avermectins, aversectin C, and a component of this complex, avermectin A1, were shown to change the conductivity of Ca2+-dependent Cl- channels of plasmalemma of Chara corallina cells by acting from the outer side of the cellular membrane. Low concentrations of aversectin C and avermectin A1 increased the Cl- current: K1/2 = 35 ng/ml for the whole complex and K1/2 = 21 pg/ml for A1. Relatively high concentrations of the compounds suppressed the Cl- current: K1/2 = 2.2 microg/ml for aversectin C and K1/2 = 4.2 ng/ml for A1. The Hill coefficient for the interaction of avermectin A1 with the corresponding targets was identical for stimulation and suppression of the Cl- current: 2.8 and 2.5, respectively. Bicuculline, a nonspecific inhibitor of the GABAa receptors, did not influence stimulation of Cl- currents caused by low concentrations of avermectins, but at the same time blocked suppression of the Cl- currents by high concentrations of avermectins. Avermectins A2, B1, B2, abamectin and 22,23-dihydroavermectin B1 (ivermectin) did not affect the Cl- currents of Chara corallina cells.
Drinyaev
V A
VA
Pharmbiomed Research Centre of Biology, 12a Selskokhozyaistvennaya Street, Moscow, Russia, 129226.
Mosin
V A
VA
Kruglyak
E B
EB
Sterlina
T S
TS
Kataev
A A
AA
Berestovsky
G N
GN
Kokoz
Y M
YM
D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000502:physiology*; D018118:Chloride Channels / Q000187:drug effects* / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D056890:Eukaryota; D007559:Ivermectin / Q000031:analogs & derivatives / Q000494:pharmacology*; D018408:Patch-Clamp Techniques
D018118:Chloride Channels; D002712:Chlorides; D007559:Ivermectin; C019264:avermectin; D002118:Calcium