Effect of angiotensin II type 1 receptor on delayed rectifier potassium current in catecholaminergic CATH.a cells

AIM: To study the modulatory effects of angiotensin Ⅱ (Ang Ⅱ) on the delayed rectifier potassium (Kv) current (IKv) and its underlying intracellular mechanism in the catecholaminergic system of rats. METHODS: AT1 and AT2 receptors of the differentiated and undifferentiated CATH.a cells were determined by radioligands binding assay. The IKv was recorded with the whole cell patch-clamp configuration in voltage clamp mode on CATH.a cells. RESULTS: The Ang Ⅱ receptor proteins including AT1 and AT2 receptors were expressed in CATH.a cells, and the number of the former was significantly more than the latter (P<0.01). The IKv of CATH.a cells was reduced by superfusion with the Ang Ⅱ (100 nmol/L) (P<0.05) in the presence of the AT2 receptor antagonist PD123319, but was not affected by only superfusion with PD123319. The effect of Ang Ⅱ on IKv in CATH.a cells was completely inhibited by addition of AT1 receptor antagonist losartan. Superfusion with Ang Ⅱ (100 nmol/L) plus U73122, an inhibitor of