Other categories referring to A single-electrode voltage-clamp technique was employed on slices to examine slow AHP. This was achieved by using conventional procedures to evoke an AHP in current clamp, followed rapidly by a switch into voltage clamp (hybrid clamp). The AHP current showed a dependence on extracellular K+ close to that predicted by the Nernst equation. It could be blocked by Cd2+ or norepinephrine, showed a requirement for voltage-dependent Ca2+ entry, but did not show any clear intrinsic voltage dependence. Once activated, AHP current is not turned off by hyperpolarizing the membrane potential