THE PHYSIOLOGICAL AND BIOLOGICAL SIGNIFICANCES OF HUMAN ATRIAL-NATRIURETIC-PEPTIDE IN NEONATES

The purpose of our study was to analyze the physiological and biological significances of the high human atrial natriuretic peptide (hANP) levels during early post-natal period. The absolute values or changes of plasma hANP concentrations did not correlate with the absolute values or changes of body weight, blood pressure, urinary sodium/creatinine and urinary aldosterone/creatinine ratios. Gel permeation chromatography of samples from two neonates revealed the presence of two molecular forms of hANP, α and β, both in the plasma and urine. In the plasma, the β-hANP was predominant on the 3rd day of life and the α-hANP on the 6th day of life. The change from one form to another was independent of the absolute value of hANP. We obtained no evidence suggestive of a physiological role of the high plasma hANP concentration during the early post-natal period. However, because of biological differences between these two fractions, their distribution must be taken into account when attempting to interpret the high hANP values observed in neonates.