Differential effects of angiotensin II and noradrenaline on tubular rejection of sodium produced by ANP in rats.

The effect of Atrial Natriuretic Peptide (ANP) on renal tubular sodium handling (FENa) in the presence of converting enzyme inhibition (CEI), the AII antagonist Saralasin (SAR), noradrenaline (NA) and angiotensin II (AII) infusions was investigated. FENa and increases in FENa produced by ANP were significantly lower with CEI (p 0.66) whereas without CEI but with ANP (MAP 113±2 mmHg) FENa was significantly increased by NA (2.34%±0.36, p < 0.02). With AII+CEI+ANP, MAP was restored to 110±5 mmHg, and FENa was highly significantly increased (0.99%±0.20 to 3.04%±0.39, p < 0.0003) in excess of that expected due to pressure effects alone. It is concluded the additional effect of All on FENa (3.04 versus 1.25% with NA) at equivalent perfusion pressures are due to a separate additive phenomen...