[Enhancement of potential-dependent inactivation of calcium channels of mollusk neurons by tolbutamide].
A two-microelectrode voltage-clamp method was used to measure a potential-dependent Ca-current (ICa) on isolated snail neurons. Tolbutamide (1-5 mmol/l) and H-8 (1-30 mumol/l), inhibitors of kinase A, caused a decrease in the peak amplitude and an acceleration of the ICa decay during a depolarizing step. In the presence of tolbutamide a slow (tau 2) time constant of the ICa decay has grown 2-3 times stronger than fast (tau 1) time constant. Curves of inactivation obtained in double-pulse experiments have shown that after tolbutamide application an inactivation of the ICa enhanced when prepulses were to +30(-)+70 mV. The results suggest that dephosphorylation of Ca(2+)-channels enhances a potential-dependent component of the ICa inactivation.
Solntseva
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D000818:Animals; D015220:Calcium Channels / Q000187:drug effects*; D006372:Helix, Snails / Q000187:drug effects*; D066298:In Vitro Techniques; D007546:Isoquinolines / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects*; D010770:Phosphotransferases / Q000037:antagonists & inhibitors*; D014044:Tolbutamide / Q000494:pharmacology*
D015220:Calcium Channels; D007546:Isoquinolines; C053177:N-(2-(methylamino)ethyl)-5-isoquinolinesulfonamide; D014044:Tolbutamide; D010770:Phosphotransferases
Usilenie potentsialzavisimoĭ inaktivatsii kal'tsievykh kanalov neĭronov molliuska tolbutamidom.