Atrial natriuretic peptide blocks the renal vasoconstrictor response to hypertonic saline in the dog

The role of atrial natriuretic peptide to modulate the renal tubuloglomerular feedback response was examined in the dehydrated anesthetized dog using an infusion of hypertonic sodium chloride to increase renal plasma sodium concentration by 30 mEq/l as the stimulus to activate the tubuloglomerular feedback. Two sequential infusions of hypertonic sodium chloride into the renal artery for 10 min were separated by 90 min, and various interventions were introduced before the second hypertonic saline infusion. In the first group of dogs, the first infusion of hypertonic saline resulted in a significant decrease in renal blood flow from 234 +/- 36 to 199 +/- 31 ml/min, but when atriopeptin III (APIII) was infused into the renal artery at 3 x 10(-10) mol/min, the repeat infusion of hypertonic saline resulted in a significant increase in blood flow from 221 +/- 28 to 269 +/- 35 ml/min that was maintained throughout the 10 min of hypertonic saline. In the second group of dogs only the vehicle for APIII was infused during the second hypertonic saline infusion. In these dogs, renal blood flow decreased significantly the first time from 201 +/- 17 to 170 +/- 16 ml/min, and the second time from 232 +/- 22 to 177 +/- 20 ml/min. In a third group of dogs, the vasodilator sodium nitroprusside, a stimulator of smooth muscle soluble guanylate cyclase, was infused into the renal artery during the second hypertonic saline infusion.(ABSTRACT TRUNCATED AT 250 WORDS)