Salt Sensitivity and Central Dopaminergic Activity in Patients With Essential Hypertension

The pathophysiological role of the central dopaminergic mechanism in human essential hypertension (EHT) is still unknown, so we investigated a possible relationship between the central dopaminergic activity and salt sensitivity to blood pressure in patients with EHT. We divided 22 inpatients with EHT into salt-sensitive (SS, n = 11) and nonsalt-sensitive (NSS, n = 11) groups according to an 8% increase of mean blood pressure (MBP) when dietary salt intake was increased from 2 g/day to 20 g/day for two periods of 7 days each. The change of central dopaminergic activity by salt load was evaluated as the percentage change of plasma prolactin (PRL) response to a small dose (25 μg of thyrotropin-releasing hormone (TRH) administered intravenously. The mean percentage change of PRL response by salt load in the SS group was −9.4 ± 8.5% (mean ± SEM), which was remarkably lower than the 26.8 ± 5.5% in the NSS group (P