Aspirin Attenuates Pulmonary Hypertension, Lowers Serotonin

[allblues]

Found this rat study. The main takeaway for me was the inhibition of serotonin release from platelets by inhibiting platelet aggregation. Perhaps this is a common beneficial mechanism for many "blood thinning" chemicals, steroids etc.

Aspirin attenuates pulmonary arterial hypertension in rats by reducing plasma 5-hydroxytryptamine levels.
Aspirin attenuates pulmonary arterial hypertension in rats by reducing plasma 5-hydroxytryptamine levels. - PubMed - NCBI

Pulmonary arterial hypertension (PAH) is characterized by increasing pulmonary pressure, right ventricular failure, and death. The typical pathological changes include medial hypertrophy, intimal fibrosis and in situ thrombosis. Serotonin (5-HT) and other factors contribute to the development of pathologic lesions. Aspirin (ASA), a platelet aggregation inhibitor, inhibits 5-HT release from platelets.

The degree of 5-HT reduction was associated with systolic PAP, right ventricular hypertrophy and wall thickness of pulmonary arterioles in rats. These results showed that ASA treatment effectively attenuated MCT-induced pulmonary hypertension, right ventricular hypertrophy, and occlusion of the pulmonary arteries. The effects of ASA was associated with a reduction of 5-HT.

Small human study where they used it alongside a calcium channel blocker;
[The use of aspirin in patients with primary pulmonary hypertension]. - PubMed - NCBI

A study with negative findings from the same year as the first study. I haven't read through it.
A Randomized Clinical Trial of Aspirin and Simvastatin for Pulmonary Arterial Hypertension: ASA-STAT