Intracellular injection of PEP-22 elicited an increase in delayed rectifier K+ current in cultured rat neurons similar to ANG II, an effect abolished by pertussis toxin and okadaic acid.
This study provides direct evidence linking the cloned AT2 receptor to the modulation of delayed rectifier K+ current in neurons via Gi protein and PP2A.
Angiotensin II (ANG II) stimulates the delayed rectifier K+ current (IK) in neurons cultured from rat hypothalamus and brain stem via AT2 receptors, and this effect involves activation of a Gi protein and protein phosphatase 2A (PP2A). However, there was no evidence that the AT2 receptor involved in this response was the same as the recently cloned AT2 receptor. In the present study, intracellular injection of a 22-amino acid peptide (PEP-22) corresponding to the putative third intracellular loop of the cloned AT2 receptor elicited an increase in IK in cultured neurons that was similar to the effect produced by ANG II. Furthermore, this effect of PEP-22 was abolished by pertussis toxin (200 ng/ml, 24 h) pretreatment and also by superfusion of the PP2A inhibitor okadaic acid (10 nM), suggesting the involvement of Gi protein and PP2A, respectively. Intracellular injection of a random peptide or normal pipette solution did not affect neuronal IK. This is direct evidence to link the cloned AT2 receptor to a defined response elicited by ANG II.
Kang et al. (Sun,) conducted a other in Neurons cultured from rat hypothalamus and brain stem. Intracellular injection of PEP-22 (22-amino acid peptide) vs. Random peptide or normal pipette solution was evaluated on Delayed rectifier K+ current (IK). Intracellular injection of PEP-22 elicited an increase in delayed rectifier K+ current in cultured rat neurons similar to ANG II, an effect abolished by pertussis toxin and okadaic acid.