Calcium release from InsP3-sensitive internal stores initiates action potential in Chara.
Neomycin and U73122 are known to suppress inositol 1,4,5-trisphosphate (InsP3) production by inhibition of phospholipase C. We studied the effects of these inhibitors on the excitatory currents, Iex, in Chara corallina under voltage-clamp conditions. Computer simulations of the experimental effects by a minimum model for the excitatory reaction pathway allow the assignment of the inhibitory effects to one specific reaction step, i.e. the release of Ca2+ from InsP3-sensitive internal stores. In contrast, the inhibitory effect of La3+ on Iex suggests inactivation of Cl- channels. Furthermore, ryanodine-sensitive Ca2+ stores seem to be irrelevant for electrical excitation in Chara.
Albrecht-von-Haller-Institut für Pflanzenwissenschaften, Abteilung Biophysik der Pflanze, Universität Göttingen, Germany.
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Biskup
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Gradmann
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Thiel
D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D000460:Chlorophyta / Q000502:physiology*; D004553:Electric Conductivity; D004963:Estrenes / Q000494:pharmacology; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism* / Q000494:pharmacology; D007811:Lanthanum / Q000494:pharmacology; D008564:Membrane Potentials; D008954:Models, Biological; D009355:Neomycin / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D012433:Ryanodine / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
D002121:Calcium Channel Blockers; D004963:Estrenes; D011760:Pyrrolidinones; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D012433:Ryanodine; D007811:Lanthanum; D015544:Inositol 1,4,5-Trisphosphate; D010738:Type C Phospholipases; D009355:Neomycin; D002118:Calcium