Molecular characterization of Kv2.1 channels in sheep vasculature: Role of Kv channels in regulating vascular tone

The voltage‐gated potassium channel 2.1 (Kv2.1) is regarded as one of the primary oxygen sensitive potassium channels in the pulmonary circulation. The dilator function of Kv2.1 is enhanced in isolated sheep conduit compared to resistance pulmonary arteries, and may be increased during development of the same animal. However, neither the functional role nor distributions of Kv2.1 in other vasculatures have been described in detail. Thus, the goal of this study was to use RT‐PCR and tension‐recording to compare the transcript expression and dilator influence of Kv2.1 channels between isolated sheep conduit and resistance pulmonary, coronary and renal arteries. Using human Kv2.1 channel primers, we demonstrated the expression of Kv2.1 channel mRNA in all vascular preparations. 4‐Aminopyridine (4‐AP) (0.001–3 mM), a nonspecific blocker of Kv channels, produced concentrationdependent contractions of conduit pulmonary and renal arteries. On the other hand, 4‐AP had no significant effect on the basal tone of isolated sheep resistance artery and coronary arteries. These results suggest that Kv channels may play an important role in regulating the tone of sheep conduit and renal arteries, but they do not appear to contribute to the regulation of basal tone in resistance pulmonary arteries and coronary arteries. The latter observation raises the possibility that Kv2.1 channels are not the primary contributor to hypoxic pulmonary vasoconstriction in sheep. IVRI research support, India.