Plasma noradrenaline concentration and pressor response to infused noradrenaline in patients with borderline hypertension, and mild or moderate essential hypertension.

Abstract

In order to evaluate the significance of sympathetic nerve activity in the pathophysiology and pathogenesis of borderline hypertension or mild or moderate essential hypertension, plasma noradrenaline concentration (PNA) at supine rest and pressor response to infused noradrenaline (NA-R) were evaluated in these in-patients. A significantly positive correlation (r = 0.395, p less than 0.001) between PNA and age was found in normotensive subjects (NT), but not in essential hypertensives (EHT). In the young (below 40 years of age) group, the mean value of PNA in EHT was significantly higher (p less than 0.05) than that in NT. However no significant difference in PNA between NT and EHT was observed in the middle-age (40-59 years) and old-age (above 60 years) groups. PNA was highest in borderline hypertensives (BHT), second highest in EHT with WHO stage I (WHO-I), third in EHT with WHO stage II (WHO-II), and lowest in NT. Among these age-matched four groups, significant differences in the mean value of PNA were found between NT and BHT (p less than 0.001) or WHO-I (p less than 0.05), and between BHT and WHO-II (p less than 0.05). In a comparison of the age-matched NT, normal renin EHT (NRH) and low renin EHT (LRH), the mean value of PNA in NRH was significantly higher than that in NT (p less than 0.001) and LRH (p less than 0.001). Similar differences were observed in the peak value of PNA during 20 minutes when the head was tilted up. A close positive correlation between PNA and simultaneously measured mean arterial pressure (MAP) in the young EHT (r = 0.698, p less than 0.001) and WHO-I (r = 0.631, p less than 0.001), and a weak correlation in the middle-age EHT (r = 0.435, p less than 0.05) and NRH (r = 0.311, p less than 0.05) were demonstrated immediately after hospital admission. In the old-age EHT, WHO-II and LRH, however, no significant correlation was found between PNA and MAP. The mean value of NA-R in young (p less than 0.005) and middle-aged EHT (p less than 0.001) was significantly greater than that in respectively age-matched NT.(ABSTRACT TRUNCATED AT 250 WORDS)