Ontogeny of atrial natriuretic polypeptide in the human heart.

To elucidate the developmental changes of atrial natriuretic polypeptide in the human heart, we studied alpha-human atrial natriuretic polypeptide (alpha-hANP)-like immunoreactivity (alpha-hANP-LI) in the extracts from the hearts of three foetuses of 10, 14 and 22 weeks' gestation, a 1-day-old premature infant of 33 weeks' gestation, and two adults, alpha-hANP-LI levels in the atria of the three foetuses of 10, 14 and 22 weeks' gestation and the premature infant (31.4, 12.2, 9.25 and 15.3 nmol/g, respectively) were comparable to those in two adult atria (16.9 and 13.6 nmol/g). The ventricles also contained alpha-hANP-LI (0.763----0.0818 nmol/g with descending values with increasing gestational age) in the three foetuses and the premature infant although it was undetectable (less than 0.0162 nmol/g) in two adult ventricles. The highest alpha-hANP-LI concentration was observed in the auricles in all the hearts except in the premature infant. The concentration in the right auricle was higher than in the left during foetal life, whereas that in the left was the higher one after birth. High performance gel permeation chromatography coupled with radioimmunoassay revealed that alpha-hANP-LI in the atria and apexes of the foetuses and the premature infant consisted of gamma-hANP, beta-hANP and alpha-hANP, with gamma-hANP being the predominant form. Essentially similar gel filtration patterns were observed in the two adult atria. These results indicate that: ANP appears in human heart tissue early in foetal life; cardiac ventricles also contain ANP in the foetus, and there is probably no difference in posttranslational processing of the precursor molecule in foetal and adult hearts.