title: The sensitivity of human blood platelets to the aggregating agent ADP during different dietary sodium intakes in healthy men.
abstract: We have investigated the effect of varying sodium intake on the renin-angiotensin system, ADP-induced platelet aggregation in vitro, and blood 5-HT concentrations in 9 male volunteers. Systolic blood pressure was slightly reduced during a low sodium diet, whereas the diastolic pressure remained unchanged. Plasma renin activity and aldosterone concentration both fell significantly when sodium intake was increased; plasma angiotensin II concentration also fell, but not significantly. There was a significant fall in haematocrit after an increased sodium intake, but there was no change in the whole-blood platelet count after correcting for this. There were no significant changes in either total (i.e. PRP) or platelet 5-HT concentrations. The extent of platelet aggregation induced by 5 and 20 mumol.l-1 of ADP increased significantly when dietary sodium intake was increased. When compared with low or normal sodium intakes, lower concentrations of ADP were required to produce 50% of maximum aggregation after a high sodium intake. The 5-HT2 receptor antagonist ketanserin (1 mumol.l-1 in vitro) reduced the extent of aggregation induced by 5 mumol.l-1 ADP after the volunteers had taken a high sodium diet, whereas the angiotensin II receptor antagonist saralasin (1 nmol.l-1) increased the rate of aggregation after the low sodium diet. Thus, during a high sodium intake, human platelets become more sensitive to the aggregating agent ADP. It is possible that this effect is mediated via platelet 5-HT2 receptors, since ketanserin abolished the increase in salt-induced aggregation seen with 5 mumol.l-1 ADP.
authors.affiliation: Department of Medicine, Western General Hospital, Edinburgh, UK.
authors.forename: I F
authors.initials: IF
authors.lastname: Gow
authors.forename: M
authors.initials: M
authors.lastname: Dockrell
authors.forename: C R
authors.initials: CR
authors.lastname: Edwards
authors.forename: A
authors.initials: A
authors.lastname: Elder
authors.forename: J
authors.initials: J
authors.lastname: Grieve
authors.forename: G
authors.initials: G
authors.lastname: Kane
authors.forename: P L
authors.initials: PL
authors.lastname: Padfield
authors.forename: C J
authors.initials: CJ
authors.lastname: Waugh
authors.forename: B C
authors.initials: BC
authors.lastname: Williams
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology*; D001792:Blood Platelets / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D006801:Humans; D007650:Ketanserin / Q000494:pharmacology; D008297:Male; D010974:Platelet Aggregation / Q000187:drug effects*; D012083:Renin / Q000097:blood / Q000187:drug effects; D012084:Renin-Angiotensin System / Q000187:drug effects; D012504:Saralasin / Q000494:pharmacology; D012701:Serotonin / Q000097:blood; D012982:Sodium, Dietary / Q000008:administration & dosage* / Q000652:urine
chemical_list: D012982:Sodium, Dietary; D012701:Serotonin; D000244:Adenosine Diphosphate; D007650:Ketanserin; D012083:Renin; D012504:Saralasin