Lack of renal vasodilation during intrarenal infusion of synthetic atriopeptin II in conscious intact SHR.

Synthetic atriopeptin II (APII) was infused directly into the right renal artery of intact conscious SHR at rates of 0.25-1 microgram/kg/min, while simultaneously measuring blood pressure (MAP) and selected regional blood flows. The latter were measured using chronically implanted miniaturized Doppler flowprobes that were placed on the right and left renal artery, superior mesenteric artery and abdominal aorta. The effects of intrarenally (i.r.) infused APII on these vascular beds were compared to the effects of the same amounts of APII given intravenously (i.v.) in the same SHR. I.r. and i.v. infusions caused similar reductions of MAP and all four blood flows. Also effects on calculated resistances were comparable, implying that resistance increased most in the mesentery and least in the two kidneys. The increase in right renal resistance during i.v. infusions of APII was not different from the effect during i.r. infusions. Also, during i.r. infusions into the right kidney, effects on the left and right kidney were not different. Our observations suggest that synthetic APII has no direct effects on the renal vasculature of intact conscious SHR.