Low-temperature induced transmembrane potential changes in the liverwort Conocephalum conicum.
Intracellular microelectrode measurements revealed that the liverwort Conocephalum conicum generates all-or-none action potentials (APs) in response to a sudden temperature drop. In plants with anion and potassium conductance blocked, dose-dependent voltage transients (VTs) were evoked by cold stimuli. These VTs did not propagate. When the external concentration of Ca(2+) was decreased or calcium channel inhibitors (La(3+), Gd(3+), verapamil, Mg(2+), Mn(2+)) were used, inhibition of VTs was observed. Amplitudes of both APs and VTs grew when Sr(2+) ions, known to release calcium from internal stores, were added to the medium. Neomycin, which suppresses phospholipase C and indirectly affects inositol triphosphate formation, caused substantial inhibition of both APs and VTs. It is concluded that a temperature drop elucidated membrane potential changes due to calcium influx both from external and internal stores.
Krol
Elzbieta
E
Department of Biophysics, Institute of Biology, Maria Curie-Sklodowska University, Akademicka 19, 20-033 Lublin, Poland. krolik@biotop.umcs.lublin.pl
Dziubinska
Halina
H
Trebacz
Kazimierz
K
D000222:Adaptation, Physiological / Q000187:drug effects / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology*; D003080:Cold Temperature; D005682:Gadolinium / Q000494:pharmacology; D035926:Hepatophyta / Q000187:drug effects / Q000502:physiology*; D007811:Lanthanum / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D009355:Neomycin / Q000494:pharmacology; D013324:Strontium / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D008345:Manganese; D007811:Lanthanum; D005682:Gadolinium; D014700:Verapamil; D009355:Neomycin; D008274:Magnesium; D002118:Calcium; D013324:Strontium