Effect of dopamine and dopamine-antagonist infusion on blood platelet count, size and release reaction in hypertensive and normotensive subjects

Abstract

To examine the effect of dopamine on in vivo platelet function and a possible platelet contribution to the clearance of dopamine we measured platelet count, platelet size and plasma concentration of the platelet specific protein p¹-thromboglobulin (BTG) in groups of 40 year old untreated hypertensive and normotensive men. One hypertensive (n=10) and one normotensive (n=10) group received dopamine infusion at doses from 0.5 to 2.0 μg/kg/min which increased plasma dopamine 100-fold from baseline. Two other groups of hypertensive (n — 10) and normotensive (n= 11) subjects received 10 mg of the dopamine antagonist metoelopramide intravenously, upon which serum prolactin concentration increased 10-fold. No significant effect on platelet function in any group was observed during these interventions. Platelet phenol-sulphotransfcrase may contribute to dopamine conjugation. However, the selected platelet parameters correlated only weakly with dopamine kinetics timing the infusion.

Neither dopamine nor a dopamine antagonist altered the selected platelet parameters, nor did these parameters influence the clearance of dopamine during a short-lasting pharmacological infusion.

Key Words:

• β-thromboglobulin
• metoelopramide