Kv7 channels modulate adrenoceptor‐mediated activity in rat renal artery

Abstract

KCNQ‐encoded voltage‐dependent potassium channels (Kv7) regulate vascular smooth muscle contractility. This study examines the contribution of Kv7 channels to physiological vascular reactivity in the rat renal artery. Recordings of isometric tension were made in response to various vasoconstrictors and dilators in the presence and absence of the Kv7 channel blocker linopirdine. Contractions in response to the α‐adrenoceptor agonist methoxamine were enhanced in the presence of linopirdine (1 μM; pEC50, 6.2±0.1 vs 5.6±0.03 vehicle control; n=5–7). However, linopirdine had no effect on contractions to the thromboxane‐mimetic U46619. In pre‐constricted renal arteries, β‐adrenoceptor‐mediated vasodilation to isoproterenol was attenuated in the presence of linopirdine (10 μM; Emax, 50.2±18.7% vs 95.7±5.8% vehicle control; n=4), but was unaffected by the non‐selective Kv1 channel blocker 4‐aminopyridine (1 mM). Dilation to the nitric oxide donor sodium nitroprusside was unaltered by linopirdine. The present data suggest that Kv7 channels may play a physiological role in α and β‐adrenoceptor‐mediated vascular activity. Supported by the British Heart Foundation.