The relationship between single-channel and whole-cell conductance in the T-type Ca2+ channel Cav3.1

Abstract

In T-type Ca2+ channels, macroscopic IBa is usually smaller than ICa, but at high Ca2+ and Ba2+, single-channel conductance (γ) is equal. We investigated γ as a function of divalent concentration and compared it to macroscopic currents using Cav3.1 channels studied under similar experimental conditions (TEAo and Ki). Single-channel current-voltage relationships were nonlinear in a way similar to macroscopic open-channel I/Vs, so divalent γ was underestimated at depolarized voltages. To estimate divalent γ, concentration dependence, iDiv, was measured at voltages,