Angiotensin II AT2 receptors act as functional antagonist for the AT1 receptors in various tissues. We have previously reported that activation of the renal AT2 receptors promotes natriuresis and diuresis, however, the mechanism is not known. Present study was designed to investigate whether activation of AT2 receptors affects the activity of Na+, K+-ATPase (NKA), an active tubular sodium transporter, in the proximal tubules isolated from Sprague-Dawley rats. The AT2 receptor agonist CGP42112 (10-10- 10-7M) produced a dose dependent inhibition of the NKA activity (9-38%). The presence of the AT2 receptor antagonist PD123319 (1µM) shifted the inhibitory dose response curve to the right suggesting the involvement of the AT2 receptors. The AT1 receptor antagonist losartan (1µM) did not affect the CGP42112 (100nM)-induced inhibition of the NKA activity. The presence of guanylyl cyclase inhibitor ODQ (10µM) and the nitric oxide synthase inhibitor L-NAME (100nM) abolished the CGP42112 (100nM) induced NKA inhibition. CGP42112 also, in a dose dependent manner, stimulated NO production (~0-230%) and cGMP accumulation (~25-100%). The CGP42112 (100nanoM) induced NO and cGMP increases were abolished by the AT2 receptor antagonist PD123319, ODQ, and L-NAME. The data suggest that the activation of the AT2 receptor via stimulation of NO/cGMP pathway causes inhibition of NKA activity in the proximal tubules. This phenomenon provides a plausible mechanism responsible for the AT2 receptor mediated natriuresis/diuresis in rodents.