ABSTRACT

This chapter provides the most direct measure of hemichannel behavior at the single-channel level. It focuses on the technical aspects of performing high-quality recordings using an overexpression system as well as acutely dissociated adult cardiomyocytes expressing endogenous connexin 43 (Cx43). The chapter demonstrates the presence of single-channel plasma membrane currents in ventricular cardiomyocytes with biophysical behaviors that are typical for Cx43 hemichannels. The functional expression of Cx43 hemichannels in heterologous systems provides the easiest way for addressing the biophysical fingerprint of hemichannels. The chapter describes whole-cell patch clamp recordings in an overexpression system that establishes the signature of Cx43 hemichannels, which consists of their unitary conductance, their reversal potential, their Vm-sensitivity, and their activation kinetics. Cx43-expressing plasmid may include a fluorescent protein such as a GFP tagged to the Cx43CT for identifying successfully transfected cells. Cx43 hemichannels have emerged as active contributors to membrane conductance and cellular responses, with a broad spectrum of functional implications.