Temperature dependence of T-type calcium channel gating.
T-type calcium channel isoforms are expressed in a multitude of tissues and have a key role in a variety of physiological processes. To fully appreciate the physiological role of distinct channel isoforms it is essential to determine their kinetic properties under physiologically relevant conditions. We therefore characterized the gating behavior of expressed rat voltage-dependent calcium channels (Ca(v)) 3.1, Ca(v)3.2, and Ca(v)3.3, as well as human Ca(v)3.3 at 21 degrees C and 37 degrees C in saline that approximates physiological conditions. Exposure to 37 degrees C caused significant increases in the rates of activation, inactivation, and recovery from inactivation, increased the current amplitudes, and induced a hyperpolarizing shift of half-activation for Ca(v)3.1 and Ca(v)3.2. At 37 degrees C the half-inactivation showed a hyperpolarizing shift for Ca(v)3.1 and Ca(v)3.2 and human Ca(v)3.3, but not rat Ca(v)3.3. The observed changes in the kinetics were significant but not identical for the three isoforms, showing that the ability of T-type channels to conduct calcium varies with both channel isoform and temperature.
Iftinca
M
M
Department of Physiology and Biophysics, University of Calgary, 3330 Hospital Drive Northwest, Calgary, Canada T2N 4N1.
McKay
B E
BE
Snutch
T P
TP
McRory
J E
JE
Turner
R W
RW
Zamponi
G W
GW
D000818:Animals; D001831:Body Temperature / Q000502:physiology*; D020747:Calcium Channels, T-Type / Q000235:genetics*; D020013:Calcium Signaling / Q000235:genetics*; D002460:Cell Line; D002462:Cell Membrane / Q000235:genetics*; D006801:Humans; D015640:Ion Channel Gating / Q000235:genetics*; D007700:Kinetics; D008564:Membrane Potentials / Q000235:genetics; D026901:Membrane Transport Proteins / Q000235:genetics; D009420:Nervous System / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D018408:Patch-Clamp Techniques; D020033:Protein Isoforms / Q000235:genetics; D051381:Rats
C121855:CACNA1G protein, human; C479952:CACNA1H protein, human; C469757:CACNA1I protein, human; D020747:Calcium Channels, T-Type; D026901:Membrane Transport Proteins; D020033:Protein Isoforms