Fig. 3
From: The role of circulating thrombospondin-1 in patients with precapillary pulmonary hypertension
Locally linear non-parametric regression of circulating TSP-1 by PVRI and CI. The graph shows circulating TSP-1 levels based on a non-parametric regression model, which uses linear functions to fit the local data points. The model resembles a saddle form, suggesting a relative minimum of net TSP-1 production at normal CI and and increase of TSP-1 with both low and high CI. While TSP-1 increases with vascular resistance, extreme resistance might be due to loss of total vascular area and therefore reduction of TSP-1 producing cells. Hence, TSP-1 levels follow a reverse U-shape. This underlines the possible association of TSP-1 with shear stress at the pulmonary endothelium