L-type and T-type Ca2+ current in cultured ventricular guinea pig myocytes.
The aim of this investigation was to study L-type and T-type Ca(2+) current (I(CaL) and I(CaT)) in short-term cultured adult guinea pig ventricular myocytes. The isolated myocytes were suspended in serum-supplemented medium up to 5 days. Using whole-cell patch clamp techniques ICaL and ICaT were studied by applying voltage protocols from different holding potentials (-40 and -90 mV). After 5 days in culture the myocytes still showed their typical rod shaped morphology but a decline in cell membrane capacitance (26 %). The peak density of ICaT was reduced significantly between day 0 (-1.6+/-0.37 pA/pF, n=9) and day 5 (-0.4+/-0.13 pA/pF, n=11), whereas peak ICaL density revealed no significant differences during culturing. The I(CaT)/I(CaL) ratio dropped from 0.13 at day 0 to 0.05 at day 5. Compared with day 0 I(CaL) the steady state inactivation curve of day 1, day 3 and day 5 myocytes was slightly shifted to more negative potentials. Our data indicate that guinea pig ventricular L-type and T-type Ca(2+) channels are differently regulated in culture.
Zorn-Pauly
K
K
Institut für Mediziniche Physik und Biophysik, Universität Graz, Harrachgasse 21, A-8010 Graz, Austria.
Schaffer
P
P
Pelzmann
B
B
Bernhart
E
E
Lang
P
P
Koidl
B
B
D000818:Animals; D020746:Calcium Channels, L-Type / Q000502:physiology*; D020747:Calcium Channels, T-Type / Q000502:physiology*; D002478:Cells, Cultured; D006168:Guinea Pigs; D006352:Heart Ventricles / Q000166:cytology; D009206:Myocardium / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D016276:Ventricular Function
D020746:Calcium Channels, L-Type; D020747:Calcium Channels, T-Type