Intercellular Electrical Coupling in Vascular Cells Present in Rat Intact Cerebral Arterioles

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Abstract
Using arterioles dissected from rat cerebral pial membrane, we investigated cell-to-cell communication by means of the amphotericin-B-perforated whole-cell patch clamp technique. During a brief voltage step or ramp in voltage clamp mode, the leak current through the membrane of a smooth muscle cell in situ in an arteriole was attenuated by different types of gap junction inhibitors. Macroscopic current recording via two electrodes attached to adjacent smooth muscle cells or to a smooth muscle cell and a nearby endothelial cell revealed transjunctional current flow between cells of the same or different types. The pseudo-junctional conductance-voltage relationship obtained from adjacent smooth muscle cells differed from that obtained from a smooth muscle cell and an endothelial cell (symmetrical for the former and asymmetrical for the latter). Single- or multiple-channel events could be recorded from weakly coupled cells of the two types: simultaneous, equal-sized events in opposite directions were recorded via two electrodes, demonstrating electrical coupling directly between cell pairs. The single-channel conductance observed most frequently varied: 200–230 pS for pairs of two smooth muscle cells and 240–260 pS for mixed pairs. These data suggest the existence of differential patterns of electrical communication in vascular cells present in rat intact cerebral arterioles.

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