Increased plasma concentrations of prostacyclin metabolite 6-keto-PGF1 alpha in essential hypertension. Influence of therapy with labetalol.
To evaluate the role of the vasoactive prostaglandins prostacyclin and thromboxane A2 in essential hypertension, the stable metabolites 6-keto-PGF1 alpha and thromboxane B2, respectively, were measured in plasma before and after therapy in 7 patients. During the placebo phase, plasma 6-keto-PGF1 alpha levels were significantly greater than normal. Plasma thromboxane B2 levels were not statistically different from those in normal subjects. After intravenous administration of labetalol to the point of blood pressure reduction, neither plasma 6-keto-PGF1 alpha nor thromboxane B2 values changed. With prolonged oral labetalol therapy and concurrent regulation of blood pressure, a significant decrease in plasma 6-keto-PGF1 alpha levels occurred while thromboxane B2 values remained unaltered. Elevation of plasma 6-keto-PGF1 alpha in untreated hypertensive subjects suggests that enhanced vessel wall prostacyclin synthesis may be a protective mechanism to prevent organ damage. As blood pressure is controlled this increase is no longer needed, and prostacyclin generation returns to normal.
D000284:Administration, Oral; D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000187:drug effects; D004983:Ethanolamines / Q000627:therapeutic use*; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D006973:Hypertension / Q000097:blood* / Q000188:drug therapy / Q000503:physiopathology; D007741:Labetalol / Q000008:administration & dosage / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D011460:Prostaglandins F / Q000097:blood*; D013929:Thromboxane B2 / Q000097:blood
D004983:Ethanolamines; D011460:Prostaglandins F; D013929:Thromboxane B2; D007741:Labetalol; C100006:prostaglandin F1