In Vitro: PF-543 (10-1000 nM; 24?hours; PASM cells) treatment abolishes SK1 expression at nM concentrations. ?PF-543 (0.1-10 μM; 24 hours; PASM cells) treatment induces caspase-3/7 activity. ?PF-543 inhibits C17-S1P formation in 1483 cells with an IC50 of 1.0 nM. ?SphK1 inhibition by PF-543 causes a dose-dependent depletion of the intracellular level of S1P with EC50 concentration of 8.4 nM and a concomitant elevation of the intracellular level of sphingosine in 1483 cells. The level of endogenous S1P in 1483 cells after a 1 h treatment with 200 nM PF-543 is decreased 10-fold, producing a proportional increase in the level of sphingosine.
In Vivo: PF-543 (1 mg/kg; intraperitoneal injection; every second day; for 21 days; female C57BL/6 J mice) treatment has no effect on vascular remodelling but reduces right ventricular hypertrophy. The protection involves a reduction in the expression of p53 and an increase in the expression of anti-oxidant nuclear factor Nrf-2. ?Mice are initially dosed (ip) with 10 mg/kg or 30 mg/kg of PF-543 for 24 h and the T1/2 is 1.2 h in blood samples. Administration of 10 mg/kg PF-543 for 24 h to mice induces a decrease in SK1 expression in pulmonary vessels.