[A study on dynamics of human atrial natriuretic polypeptide based on loading tests with angiotensin-II and NaCl in...

In order to investigate the regulating mechanism of Atrial Natriuretic Polypeptide (ANP) in women with Pregnancy Induced Hypertension (PIH), we measured plasma ANP levels with or without loading tests such as Angiotensin-II loading test or NaCl loading test. Plasma ANP in normal pregnancy gradually increased with advancing gestation, and decreased immediately after parturition. In PIH cases the ANP concentration was significantly higher (mild PIH 156.7 +/- 9.9 pg/ml, severe PIH 165.8 +/- 12.2 pg/ml) than in normal pregnancy cases (138.2 +/- 3.2 pg/ml). In Angiotensin-II loading, a significant positive correlation (r = 0.68, p less than 0.01) between the variance of mean arterial blood pressure (delta MAP) and that of ANP (delta ANP) was observed in normal pregnant women of third trimester, whereas in mild PIH cases a significant negative correlation (r = -0.59, p less than 0.01) was noted between them, and in severe PIH cases there existed no significant correlation. In normal pregnancy and in mild PIH, plasma ANP showed a 15.2% increase at fifteen minutes after 5% NaCl loading. In severe PIH there were no significant change in plasma ANP during and at fifteen minutes after NaCl loading test. From these results, it is suggested that the onset, the duration or the aggravation of hypertension in pregnancy may be partly due to the abnormality of ANP secretion.