T-type Ca²⁺ channels in cerebral arteries: approaches, hypotheses, and speculation.

Cerebral blood flow is controlled by a network of resistance arteries that dilate and constrict to mechanical and chemical stimuli. Vasoactive stimuli influence arterial diameter through alterations in resting membrane potential and the influx of Ca²⁺ through voltage-gated Ca²⁺ channels. Historically, L-type Ca²⁺ channels were thought to be solely expressed in cerebral arterial smooth muscle. Recent studies have, however, challenged this perspective, by providing evidence of T-type Ca²⁺ channels in vascular tissues. This perspective piece will introduce T-type Ca²⁺ channels, their electrophysiological properties, and potential roles in arterial tone development. We begin with a brief overview of Ca²⁺ channels and a discussion of the approaches used to isolate this elusive conductance. We will then speculate on how the two T-type Ca²⁺ channels expressed in cerebral arterial smooth muscle might differentially influence arterial tone. This discovery of T-type Ca²⁺ channels alters our traditional understanding of Ca²⁺ dynamics in vascular tissue and fosters new avenues of research and insight into the basis of arterial tone development.