Four-hour infusions of synthetic atrial natriuretic peptide in normal volunteers.
Two doses of synthetic atrial natriuretic peptide (0.5 and 5.0 micrograms/min) and its vehicle were infused intravenously for 4 hours in eight salt-loaded normal volunteers, and the effect on blood pressure, heart rate, renal hemodynamics, solute excretion, and secretion of vasoactive hormones was studied. The 0.5 micrograms/min infusion did not alter blood pressure or heart rate, whereas the 5.0 micrograms/min infusion significantly reduced the mean pressure by 20/9 mm Hg after 2.5 to 3 hours and increased the heart rate slightly. Inulin clearance was not significantly changed, but the mean p-aminohippurate clearance fell by 13 and 32% with the lower and higher doses, respectively. Urinary excretion of sodium and chloride increased slightly with the lower dose. With the higher dose, a marked increase in urinary excretion of sodium, chloride, and calcium was observed, reaching a peak during the second hour of the infusion. Potassium and phosphate excretion did not change significantly. A brisk increase in urine flow rate and fractional water excretion was seen only during the first hour of the high-dose infusion. Signs and symptoms of hypotension were observed in two subjects. No change in plasma renin activity, angiotensin II, or aldosterone was observed during either infusion, but a marked increase occurred after discontinuation of the high-dose infusion. In conclusion, the 5 micrograms/min infusion induced a transient diuretic effect, delayed maximal natriuretic activity, and a late fall in blood pressure, with no change in inulin clearance but a dose-related decrease in p-aminohippurate clearance. Despite large amounts of sodium excreted and blood pressure reduction, no counterregulatory changes were observed in the renin-angiotensin-aldosterone system or plasma vasopressin levels during the infusion.
D000328:Adult; D000450:Aldosterone / Q000097:blood; D000804:Angiotensin II / Q000097:blood; D009320:Atrial Natriuretic Factor / Q000009:adverse effects / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D001834:Body Water / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D005919:Glomerular Filtration Rate / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007668:Kidney / Q000187:drug effects; D008297:Male; D008657:Metabolic Clearance Rate; D009318:Natriuresis / Q000187:drug effects; D010710:Phosphates / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D012083:Renin / Q000097:blood; D012964:Sodium / Q000378:metabolism; D010130:p-Aminohippuric Acid / Q000378:metabolism
D002712:Chlorides; D010710:Phosphates; D000804:Angiotensin II; D000450:Aldosterone; D009320:Atrial Natriuretic Factor; D012964:Sodium; D012083:Renin; D011188:Potassium; D002118:Calcium; D010130:p-Aminohippuric Acid