Table 1.

Glossary of symbols and parameters. We also denote a (machine or post-processing) estimate of a parameter X as X*, and the error in the estimate of the same parameter as $X^{†}$. The range of typical values are taken from [18,20–22], unless otherwise specified.

symbol	typical values	description
general
t	—	time variable
capacitance
Cf	0.3 pF	feedback shunt capacitance
Cm	5–20 pF	membrane capacitance. These are typical values for the CHO cells used in this study [14]; 100–400 pF has been measured for individual cardiomyocytes in various species [23] (∼ 190 pF for human [24]); and can be as high as 100 nF for large cells such as Xenopus oocytes [25].
Cp	3–5 pF	parasitic capacitance at the pipette/well plate; also known as ‘pipette capacitance’ in manual patch
current
Iin	—	voltage-clamp current
Iinj	—	injection current
Iion	$\mathcal{O}(1)$ nA	whole-cell ion channel current (can reach $\mathcal{O}(1)$ μA for Xenopus oocytes [25])
Ileak	—	leakage current through imperfect seal
Im	—	membrane current
Iout	—	recorded current
Ip	—	current drawn by parasitic capacitance of the pipette/well plate
Ipost	—	post-processed (leak subtracted) current
resistance
Rf	25 M$\mathrm{\Omega }$	feedback resistance
Rs	5–20 M$\mathrm{\Omega }$	series resistance between the pipette electrode and the cell
Rseal	0.5–10 G$\mathrm{\Omega }$	seal resistance of the pipette tip
time constant
τa	50–2000 μs	membrane access time constant, τa = RsCm
τsum	5–70 μs	response time of the summing amplifier
τclamp	0.8 μs	voltage-clamp time constant
τz	7.5 μs	transconductor time constant, τz = Rf Cf
voltage
Vcmd	$\mathcal{O}(100)$ mV	command voltage; follows the voltage-clamp protocols
Vclamp	$\mathcal{O}(100)$ mV	clamp voltage
Vm	$\mathcal{O}(100)$ mV	membrane potential
Voff	$\mathcal{O}(10)$ mV	offset voltage, such as amplifier offsets, electrode offsets, junction potentials, etc.
Vout	$\mathcal{O}(100)$ mV	recorded voltage, Vout = IoutRf
Vp	$\mathcal{O}(100)$ mV	pipette potential