Abstract
Pulmonary hypertension (PH) carries significant associated morbidity and mortality and the underlying molecular mechanisms of PH are not well understood. Loss-of-function mutations in TASK-1 potassium channels are associated with PH in humans. Although TASK-1 has been considered in the development of PH for over a decade, characterization of TASK-1 knockout mice has been limited to in vitro studies or in vivo studies in room air at isolated time points. The purpose of this study was twofold. First, we sought to determine if TASK-/- male and female mice developed PH over the span of one year. Second, we sought to determine the effect of chronic hypoxia, a stimulus for PH, and its recovery on PH in TASK-1-/- mice. We measured right ventricular systolic pressure (RVSP) and vascular remodeling in male and female C57BL/6 WT and TASK-1-/- mice at separate time points: 20-24 weeks and 1 year of age. Additionally, we measured RVSP and vascular remodeling in TASK-1-/- and wild-type mice between 13 and 16 weeks of age exposed to 10% hypoxia for 3 weeks followed by recovery to room air conditions for an additional 6 weeks. RVSP was similar between WT and TASK-/- mice. Male and female WT and TASK-1-/- mice all demonstrated age-related increases in RVSP, which correlated to age-related vascular remodeling in male mice but not in female mice. Male TASK-1-/- and WT mice exposed to chronic hypoxia demonstrated increased RVSP, which decreased following room air recovery. WT and TASK-1-/- male mice demonstrated vascular remodeling upon exposure to hypoxia that persisted in room air recovery. Female and male TASK-1-/- mice do not develop hemodynamic or vascular evidence for PH, but RVSP rises in an age-dependent manner independent of genotype. TASK-1-/- and WT male mice develop hypoxia-induced elevations in RVSP that decrease to baseline after recovery in room air. TASK-1-/- and WT male mice demonstrate vascular remodeling after exposure to hypoxia that persists despite recovery to room air conditions and does not correlate with RVSP normalization.
Highlights
Pulmonary hypertension (PH) affects both children and adults through various etiologies of disease but with a large associated mortality [1]
right ventricular systolic pressures (RVSP) Measurements At 20 weeks of age, there were no differences between wild-type and TWIK-related acid-sensitive K+ channels (TASK)-1−/− (C57BL/6) male mice with regards to RVSP
The K2P channel TASK-1 has been implicated in PH in human studies, but recent mouse studies have failed to show a clear role for TASK-1 in the development of PH
Summary
Pulmonary hypertension (PH) affects both children and adults through various etiologies of disease but with a large associated mortality [1]. One hypothesis surrounding the mechanisms of pulmonary vascular hypercontractility in PH involves inhibition or downregulation of potassium channels in pulmonary artery vascular smooth muscle cells (PAVSMC) [5,6,7]. Inhibition of potassium channel activity would depolarize the cell and increase intracellular Ca2+ in PAVSMCs, activating the cellular contractile machinery and subsequent increase in vascular tone [6, 7]. A role for the K2P channels in PH remained only speculation until Ma and colleagues reported that loss-of-function mutations in the TWIK-related acid-sensitive K+ channels (TASK; gene KCNK3) was identified in connection with familial PH [10]. The TASK-1 mutation was inherited in an autosomal dominant manner with incomplete penetrance, as not all family members with the mutation had evidence of disease and the carriers were unaffected
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