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\subsection*{Electrophysiological recordings and data analysis} \subsection*{Electrophysiology}  Ba\textsuperscript{2+} (or Ca\textsuperscript{2+}) currents through T-type channels expressed in oocytes were measured at room temperature 4 to 5 days after cRNA injection using a two-electrode voltage-clamp amplifier (OC-725C, Warner Instruments, Hamden, CT, USA).  Microelectrodes were pulled fromthe  capillaries \textcolor{red}{Which capillaries?}  (Warner Instruments, Hamden, CT, USA) using a pipette puller and filled with 3 M KCl and the electrode resistance was 0.5-1.1 M$\Omega$. KCl.  All electrodes used measured 0.5--1.1 M$\Omega$ of resistance.  The 10 mM Ba\textsuperscript{2+} (or Ca\textsuperscript{2+}) recording solution contained (in mM): contained:  10 Ba(OH)2 mM Ba(OH)\textsubscript{2}  (or Ca(OH)2), Ca(OH)\textsubscript{2}),  90 mM  NaOH, 1 mM  KOH, 5 mM  HEPES (pH 7.4 7.4,  adjusted with methanesulfonic acid). To get rid of remove any  contamination of from  Ca\textsuperscript{2+}-activated chloride currents, we injected the oocytes with  50 nl nL  of 50 mM BAPTA (1,2-bis$[$o-aminophenoxy$]$ ethane -N,N,N\textquoteright,N\textquoteright-tetraacetic acid) into oocytes 30-60 30--60  min before recordings, prior to recording.  This was  especially for important while  recording Ca\textsuperscript{2+} currents from oocytes.  The currents currents.  Currents  wereusually  sampled at 5 kHz and low pass filtered at 1 kHz using the pClamp system (Digidata 1320A and pClamp 8; Axon instruments, Foster City, CA, USA).   For recordings of tail currents of DmCa\textsubscript{v}3, we employed whole cell patch clamp recordings in the HEK-293 cells transiently transfected with DmCa\textsubscript{v}3.   Recordings were obtained at room temperature using an Axopatch 200A amplifier, which was connected to a computer through a Digidata 1300 A/D converter, and controlled using pCLAMP 9.2 software.   Currents were recorded in a 10 mM Ba\textsuperscript{2+} solution (in mM): 140 TEACl, 2.5 CsCl, 10 BaCl2, 1 MgCl2, 10 HEPES, 10 glucose, pH = 7.3 adjusted with TEAOH. The pipette solution contained the following (in mM): 130 CsCl, 10 HEPES, 10 EGTA, 5 MgATP, 1 NaGTP, pH = 7.4 adjusted with CsOH.   Recording pipettes were prepared from TW-150-3 capillary (World Precision Instruments, Inc., Sarasota, FL).  The pipette resistance was 2.0$\sim$3.0 M$\Omega$. Access resistance was compensated 70-80\%{} using the compensation circuit and series resistance prediction.   Data for tail currents were filtered at 10 kHz and digitized at 20 kHz.   Peak currents and exponential fits to currents were analyzed using Clampfit software (Axon instruments, Foster City, CA, USA).   Activation and inactivation time constants of T-type channel currents elicited by step pulses were estimated by fitting individual current traces with a double exponential function: $A1(1-exp(-t/\tau1)) + A2(1-exp(-t/\tau2))$ where $A1$ and $A2$ are the coefficients for the activation and inactivation exponentials, $t$ is time, and $\tau1$ and $\tau2$ are the activation and inactivation time constants, respectively.  The smooth curves for channel activation and steady-state inactivation were from fitting data with a Boltzmann equation: $1/\{1+exp[(V_{50}-V)/S_{act}]\}$, where $V_{50}$ is the potential for half-maximal activation and $S_{act}$ is the slope conductance.  Dose-response curves for Ni\textsuperscript{2+} inhibition of T-type channel currents were derived by fitting the data using a Hill equation: $B = 1/(1 + \textrm{IC}_{50}/[\textrm{Ni}^{2+}]^n)$, where $B$ is the normalized block, $\textrm{IC}_{50}$ is the concentration of $\textrm{Ni}^{2+}$ giving half maximal blockade, and $n$ is the Hill coefficient. USA) unless otherwise noted.  We used whole cell patch clamp recordings from HEK-293 cells transiently transfected with DmCa\textsubscript{v}3 to measure tail currents.   These recordings were obtained at room temperature using an Axopatch 200A amplifier connected to a computer through a Digidata 1300 A/D converter and controlled with the pCLAMP 9.2 software.  Tail currents were recorded in a 10 mM Ba\textsuperscript{2+} solution containing the following: 140 mM TEACl, 2.5 mM CsCl, 10 mM BaCl\textsubscript{2}, 1 mM MgCl\textsubscript{2}, 10 mM glucose, and 10 mM HEPES (pH 7.3, adjusted with TEAOH).  The pipette solution contained the following: 130 mM CsCl, 10 mM EGTA, 5 mM MgATP, 1 mM NaGTP, and 10 mM HEPES (pH 7.4, adjusted with CsOH).   Recording pipettes were prepared from TW-150-3 capillaries (World Precision Instruments, Inc., Sarasota, FL).  The pipette resistance was 2.0$\sim$3.0 M$\Omega$.  Access resistance was compensated 70-80\% using the compensation circuit and series resistance prediction. \textcolor{red}{What does this mean? I can't find any paper that explains it like this.}  Tail current data were filtered at 10 kHz and digitized at 20 kHz.  Peak currents and exponential fits were analyzed using the Clampfit software package (Axon instruments, Foster City, CA, USA).  The activation and inactivation time constants for the T-type currents elicited by step pulse protocols were estimated by fitting individual current traces with double exponential functions: $A1(1-exp(-t/\tau1)) + A2(1-exp(-t/\tau2))$ where $A1$ and $A2$ are the coefficients for the activation and inactivation exponentials, $t$ is time, and $\tau1$ and $\tau2$ are the activation and inactivation time constants, respectively.  The smooth curves for channel activation and steady-state inactivation were obtained by fitting the data with a Boltzmann equation: $1/\{1+exp[(V_{50}-V)/S_{act}]\}$, where $V_{50}$ is the potential for half-maximal activation and $S_{act}$ is the slope conductance.  Dose-response curves for Ni\textsuperscript{2+} inhibition of T-type channel currents were derived by fitting the data using a Hill equation: $B = 1/(1 + \textrm{IC}_{50}/[\textrm{Ni}^{2+}]^n)$, where $B$ is the normalized block, $\textrm{IC}_{50}$ is the concentration of $\textrm{Ni}^{2+}$ giving half maximal blockade, and $n$ is the Hill coefficient.