Renal effects of atrial natriuretic peptide infusion in young and adult rats

• Published in: Pediatric research Vol. 24; no. 3; pp. 333 - 337
• Main Authors: CHEVALIER, R. L, ARIEL GOMEZ, R, CAREY, R. M, PEACH, M. J, LINDEN, J. M
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD Lippincott Williams & Wilkins 01.09.1988
• Subjects: Aging; Animals; Atrial Natriuretic Factor - administration & dosage; Atrial Natriuretic Factor - pharmacology; Biological and medical sciences; Blood Pressure - drug effects; Body Weight - drug effects; Cyclic GMP - urine; Fundamental and applied biological sciences. Psychology; Glomerular Filtration Rate - drug effects; Hematocrit; Infusions, Intra-Arterial; Kidney - drug effects; Kidney - growth & development; Kidney - physiology; Natriuresis - drug effects; Organ Size - drug effects; Rats; Rats, Inbred Strains; Reference Values; Vertebrates: urinary system
• ISSN: 0031-3998; 1530-0447
• DOI: 10.1203/00006450-198809000-00012

The immature kidney appears to be less responsive to atrial natriuretic peptide (ANP) than the mature kidney. It has been proposed that this difference accounts for the limited ability of the young animal to excrete a sodium load. To delineate the effects of age on the renal response to exogenous ANP, Sprague-Dawley rats were anesthetized for study at 31-32 days of age, 35-41 days of age, and adulthood. Synthetic rat ANP was infused intravenously for 20 min at increasing doses ranging from 0.1 to 0.8 microgram/kg/min, and mean arterial pressure, glomerular filtration rate, plasma ANP concentration, urine flow rate, and urine sodium excretion were measured at each dose. Since cyclic GMP acts as a second messenger for ANP action, urinary cyclic GMP excretion also was measured. Increasing doses of ANP caused a similar decrease in MAP at all ages studied, and increased glomerular filtration rate in adult but not young rats. Increasing the dose of ANP from 0.1 to 0.4 microgram/kg/min caused a greater rise in urine flow and urinary cyclic GMP excretion in adult than young rats, and urine sodium excretion increased more in adults at all doses (p less than 0.05). However, the rise in plasma ANP concentration also was greater in adults than in young rats (p less than 0.05), indicative of greater systemic clearance of ANP in young animals. Increasing levels of plasma ANP concentration were correlated with a greater rise in urine flow in adult than young (31-32 day old) rats (p less than 0.05), but there was no differential effect on urinary cyclic GMP excretion.