Smooth Muscle K+ Channels and the Modulation of Conduction in Cerebral Arteries

Abstract

Blood flow control is dependent upon the initiation of electrical signals and their conduction along the arterial wall. The distance over which electrical phenomena conduct is governed by gap junctions and membrane resistivity. The goal of this study was to determine whether modulating ion channel activity alters membrane resistivity sufficiently to limit electrical conduction. Hamster cerebral arteries were isolated, cannulated and subjected to a conduction protocol. Focal KCl stimulation elicited a vasoconstriction that conducted robustly along the arterial wall. Manipulating voltage-dependent K+ (BKCa, Kv) channels did not produce significant changes in conduction decay; nor did modification of ATP-sensitive KATP channels. In contrast, Ba2+ blockade of inwardly rectifying (KIR) channels augmented conduction decay, an effect attributed to the loss of negative slope conductance. Conduction experiments performed for the first time on human cerebral arteries also demonstrated a robust conducted constrictor response. This study shows that selective smooth muscle K+ conductance can tune electrical communication if it retains appropriate biophysical properties.