[Temperature dependence of the conductivity of individual potential-dependent K+-channels in mollusk neurons].
Using the patch-clamp method temperature dependences of the chord conductance of single potential--dependent slow and fast K+ channels in mollusk neurons were studied. Under control conditions (20 degrees C, 0 mV, [K+]o = 1.5 mM and [K+]i = 100 mM) the conductances of the fast and slow K+ channels were equal to 20-25 pS and 30-40 pS, respectively. Besides, the temperature dependences of the currents through the K+ channels of lesser conductance (5-20 pS) were studied. Some of these channels may be regarded as subtypes of the fast and slow K+ channels named above. It was found that for the channels of all types single channel currents arise with temperature. However, in the range of 10-20 degrees C an anomalous conductance decrease at temperature elevation was observed. For all channels except for the fast one at temperatures above 20 degrees C activation energy (delta Ea) calculated from the Arrhenius plots of the currents was about 4 kcal/mol. At the temperatures below 10 degrees C delta Ea was equal to about 12 kcal/mol. In this temperature range delta Ea had a pronounced potential dependency. Temperature dependences of the fast K+ channel conductance were opposite to those of the slow K+ channel to some extent.
Tseeb
V E
VE
Geletiuk
V I
VI
Kazachenko
V N
VN
D000818:Animals; D004553:Electric Conductivity; D008195:Lymnaea; D008564:Membrane Potentials; D009474:Neurons / Q000502:physiology*; D015221:Potassium Channels / Q000502:physiology*; D013696:Temperature
D015221:Potassium Channels
Temperaturnye zavisimosti provodimosti odinochnykh potentsialozavisimykh K+-kanalov v neĭronakh molliuska.