Inward rectifier potassium channels properties

The molecular structure of the smooth muscle Kjr channel is unknown, although, based on its properties, it is likely to be a member of the IRK family. Inward rectifier potassium currents have been identified in small cerebral, coronary (see Fig. 2A), and mesenteric arterioles (<200 i.m diameter). The presence of K[r channels may be a common feature in small arteries that determine in large part peripheral vascular resistance. It is not known if Kjr channels are exclusively present in small arteries, although they have not yet been reported in larger vessels. Innervation of this size artery (<100-200 j.m) is usually sparse and therefore small arteries may be more prone to respond to metabolic demand from the tissue, as reflected by potassium efflux. Thus, the appearance of K,r channels may reflect a transition of blood flow regulation to local (tissue) control. This is an intriguing hypothesis that remains to be tested. It will be important to study systematically the distribution of the K r channel within a vascular bed, as this may have physiological consequences. Kir channels, like K and K jp channels. 

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