Pharmacological Alteration of Cellular Mechanical Properties in Pulmonary Arterial Smooth Muscle Cells of Idiopathic Pulmonary Arterial Hypertension.

BACKGROUND: Idiopathic pulmonary arterial hypertension (IPAH) is a progressive disease caused by vascular remodeling of the pulmonary arteries with elevated pulmonary vascular resistance. Recently, various pulmonary vasodilator drugs have become available in the clinical field, and have dramatically ameliorated the prognosis of IPAH. However, little is known about how the mechanical properties of pulmonary arterial smooth muscle cells (PASMCs) are altered under drug supplementation. METHODS: Atomic force microscopy (AFM) was used to investigate the mechanical properties of PASMCs derived from a patient with IPAH (PAH-PASMCs) and a healthy control (N-PASMCs) which received the supplementation of clinically used drugs for IPAH: sildenafil, macitentan, and riociguat. RESULTS: PASMCs derived from PAH-PASMCs were stiffer than those derived from N-PASMCs. With sildenafil treatment, the apparent Young's modulus (E 0) of cells significantly decreased in PAH-PASMCs but remained unchanged in N-PASMCs. The decrease in E 0 of PAH-PASMCs was also observed in macitentan and riociguat treatment. The stress relaxation AFM revealed that the decrease in E 0 of PAH-PASMCs resulted from a decrease in the cell elastic modulus and/or increase in cell fluidity. The combination treatment of macitentan and riociguat showed an additive effect on cell mechanical properties, implying that this clinically accepted combination therapy for IPAH influences the intracellular mechanical components. CONCLUSIONS: Pulmonary vasodilator drugs affect the mechanical properties of PAH-PASMCs, and there exists a mechanical effect of combination treatment on PAH-PASMCs.

Characterization of zinc uptake by mouse primary cultured astrocytes and microglia.

To elucidate the regulatory mechanism for extracellular zinc in the CNS, we examined the zinc uptake characteristics in mouse astrocytes and microglia. Zinc was taken up into the two cell types time-dependently, and the cell-to-medium concentration (C/M) ratio in the initial uptake phase in astrocytes was significantly smaller than that in microglia, while in the steady state phase, there was no difference in their C/M ratios. In both astrocytes and microglia, the zinc uptake was mediated, at least in part, by high- and low-affinity systems. There were no differences for both in the Km values for zinc uptake between astrocytes and microglia, and those for the low-affinity system in both cell types were the same as that for mouse ZIP1 reported previously. On the other hand, the Vmax values for both systems were greater in microglia than in astrocytes. Among ZIP isoforms, expression of ZIP1 was high in astrocytes and microglia. Nickel, a competitive inhibitor of ZIP1, and ZIP1 knock-down decreased zinc uptake by both types of cells. Overall, it is demonstrated that astrocytes and microglia had a similar uptake system for zinc including ZIP1, and the differences found in their uptake profiles imply that they play different roles in the regulation of extracellular zinc to maintain brain homeostasis.