Effect of dietary sodium on platelet alpha 2-adrenergic receptors in essential hypertension.
To study the aggregation, adhesion, and specific binding of an alpha 2-antagonist, [3H]rauwolscine, to the platelet membrane fractions, platelets were obtained from 30 patients with essential hypertension and nine normotensive subjects fed a high sodium diet (NaCl, 16-18 g/day) for 7 days and thereafter a low sodium diet (NaCl, 1-3 g/day) for 7 days. The patients with essential hypertension were classified as either salt responders (all those who had greater than 7% decrease in mean arterial pressure from the high to low sodium period) or salt nonresponders (all others). In salt responders, the number of alpha 2-adrenergic receptors on platelet membrane fraction was increased from 523.4 +/- 55.4 fmol/mg of protein in the high sodium period to 669.4 +/- 84.0 fmol/mg of protein in the low sodium period (p less than 0.01), whereas it did not change in salt nonresponders. In contrast, the epinephrine-induced platelet aggregation through alpha 2-adrenergic receptors was decreased in nonresponders, from 47.3 +/- 7.4% in the high sodium period to 24.5 +/- 9.3% in the low sodium period (p less than 0.05), while it did not change in responders. No significant change in the number of alpha 2-adrenergic receptors or epinephrine-induced platelet aggregation was observed in the normotensive subjects.
D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010973:Platelet Adhesiveness / Q000187:drug effects; D010974:Platelet Aggregation / Q000187:drug effects; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects* / Q000378:metabolism; D012964:Sodium / Q000008:administration & dosage*
D011942:Receptors, Adrenergic, alpha; D012964:Sodium