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 non-salt-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 micrograms) 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 less than .01). There was a significant negative correlation between the percentage change of PRL response and that of MBP by salt load (r = -0.456, P less than .05). These results suggest that a lack of activation of the central dopaminergic system by salt load may contribute in part to a rise in blood pressure in SS patients with EHT.
Department of Internal Medicine III, Kumamoto University Medical School, Japan.
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Hamasaki
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Umeda
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Sato
D000328:Adult; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D015259:Dopamine Agents / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D011388:Prolactin / Q000097:blood; D012964:Sodium / Q000494:pharmacology*; D013973:Thyrotropin-Releasing Hormone / Q000008:administration & dosage / Q000494:pharmacology
D015259:Dopamine Agents; D013973:Thyrotropin-Releasing Hormone; D011388:Prolactin; D012964:Sodium