Inhibition of platelet aggregation by capsaicin is not mediated by the TRPV1 receptor

Capsaicin is an agonist of the TRPV1 receptor which appears to play a role in the integration of the nociceptive response to a variety of noxious stimuli. In addition to neuronal effects, capsaicin can affect non‐neuronal tissue. Previous in vitro studies have demonstrated that capsaicin can inhibit the platelet aggregation response induced by collagen. However, these studies have not investigated if this occurs through the TRPV1 receptor. The purpose of the present study was to investigate if capsaicin induced platelet aggregation could be inhibited with A‐993610, a selective TRPV1 antagonist. Methods Venous blood obtained from dogs was incubated with vehicle, capsaicin, and/or A‐993610 for 10 minutes followed by the application of collagen (2 µg/ml). An aggregometer was used to quantify the platelet response. Results Capsaicin caused a significant inhibition of the collagen‐induced platelet aggregation at concentrations of 10 & 30 µg/ml. A‐993610 alone had no effect on platelet aggregation. In addition, A‐993610 did not have an effect on the inhibition of platelet aggregation by capsaicin. Discussion The current results agree with previous findings demonstrating that capsaicin inhibits platelet aggregation. However, the effects of capsaicin on platelet aggregation are not mediated via the TRPV1 receptor since the inhibition could not be blocked by a specific TRPV1 antagonist.