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Cholestyramine treatment of type IIa hypercholesterolaemia normalizes platelet reactivity against prostacyclin
P Löbel1, E Steinhagen-Thiessen, K Schrör
1Institut für Pharmakologie der Universität Düsseldorf, FRG.
Insights
Cholestyramine treatment for familial hypercholesterolaemia (FH) normalized platelet sensitivity to prostacyclin, despite not altering platelet hyperreactivity or thromboxane formation. This normalization may help prevent blood clot complications in FH patients.
Area of Science:
- Cardiovascular Medicine
- Hematology
- Pharmacology
Background:
- Familial hypercholesterolaemia (FH) is a genetic disorder characterized by high LDL cholesterol.
- Platelet hyperreactivity and altered thromboxane (TX) formation are observed in untreated FH patients.
- Prostacyclin sensitivity is reduced in platelets from FH patients.
Purpose of the Study:
- To investigate the effects of lowering plasma cholesterol with cholestyramine on platelet function in FH patients.
- To assess changes in platelet aggregation, TX formation, and sensitivity to prostacyclin (iloprost) ex vivo.
- To determine if cholestyramine treatment can normalize platelet abnormalities in FH.
Main Methods:
- Seven FH patients received cholestyramine (12 g/day) for 8-11 months.
- Platelet function was studied ex vivo in platelet-rich plasma.
- Comparisons were made between treated FH patients, untreated FH patients, and healthy controls.
Main Results:
- Untreated FH patients showed increased platelet aggregation and TX formation compared to controls.
- FH platelets exhibited reduced sensitivity to prostacyclin inhibition.
- Cholestyramine reduced total and LDL cholesterol by 21% but did not alter platelet hyperreactivity or TX formation.
- Cholestyramine treatment normalized platelet sensitivity to iloprost in FH patients.
Conclusions:
- Lowering plasma cholesterol with cholestyramine normalizes reduced platelet sensitivity to prostacyclin in FH.
- This normalization of platelet function may contribute to preventing thromboembolic complications in FH patients.
- The findings suggest a link between lipid levels and platelet responsiveness in atherosclerosis.
Abstract:
The effect of lowering total plasma and low density lipoprotein (LDL) cholesterol in heterozygous familial hypercholesterolaemia type IIa (FH) on platelet function, thromboxane (TX) formation and platelet sensitivity against iloprost, a stable prostacyclin mimetic, was studied in platelet-rich plasma ex vivo. Seven FH patients were treated with cholestyramine (12 g day 1) for 8-11 months and were compared with eight untreated FH patients and 11 healthy control subjects. In comparison with platelets from healthy controls, platelets from untreated FH patients exhibited a significantly increased aggregation response and TX formation, and a reduced reactivity against inhibition of platelet aggregation by prostacyclin. Treatment with cholestyramine for 8-11 months resulted in a 21% reduction in total serum and LDL-cholesterol. This was not accompanied by any change in platelet hyperreactivity or TX formation. However, cholestyramine treatment normalized the platelet reactivity of FH patients against iloprost, being no more different from healthy controls. It is concluded that reduction in plasma cholesterol by cholestyramine results in normalization of the reduced platelet sensitivity against prostacyclin. This might contribute to beneficial effects of cholestyramine treatment in preventing thromboembolic complications of atherosclerosis.