Abstract 15989: Loss of PLA2g6-dependent Store-operated Ca2+ Entry Protects Against Arterial Stiffening
Introduction: Arterial stiffness is strongly associated with cardiovascular disease, but the mechanism and the role of vascular smooth muscle cell (SMC) in stiffening of the arteries in aging humans are not well understood. We have previously shown that phospholipase A2 group 6 (PLA2g6)-dependent store-operated Ca2+ entry (SOCE) is involved in proliferation, migration and agonist-induced constriction of SMC.
Hypothesis: Here we tested the hypothesis that PLA2g6-dependent SOCE could be a previously unknown determinant of arterial stiffness.
Methods: A wild type (WT) and new transgenic PLA2g6ex2KO mouse model with constitutively impaired SOCE function were used for in vivo and in vitro studies. Arterial stiffness was determined by pulse wave velocity (PWV), and compared in 8 and 24 month-old (m/o) males. Aortic vasoconstriction (isometric force) was measured using organ chambers; aortic media thickness was quantified using Picrosirius red staining, and SMC layer was evaluated by immunohistochemistry. Intracellular Ca2+ was recorded in primary aortic SMC using Fura-2 imaging.
Results: Analysis of SOCE confirmed that it is significantly impaired in SMC from PLA2g6ex2KO mice: Ca2+ influx triggered by thapsigargin-induced depletion of ER Ca2+ stores was 0.71±0.04 (ΔF340/F380±SE) in PLA2g6ex2KO, and 2.67±0.14 in WT SMCs (p<0.001). Phenylephrine, but not depolarization (60mM KCl)-induced constriction of aortic rings was significantly impaired in PLA2g6ex2KO mice compared to WT (0.73±0.03g vs 1.54±0.14g; p<0.01). Arterial stiffness significantly increased with age in WT mice (3.2±0.6 m/s in 8 m/o vs 9.7±1.8 m/s in 24 m/o mice; p<0.05). Importantly, we discovered that PWV did not increase in aged PLA2g6ex2KO mice (PWV was 4.2±0.4 m/s in 8 m/o and 3.3±0.5 m/s in 24 m/o; p=0.19). At 24 m/o, PLA2g6ex2KO animals had significantly lower PWV than WT (3.3±0.5 vs 9.7±1.8m/s; p<0.05). We also found that the medial (SMC) layer of the aorta from 24 m/o PLA2g6ex2KO mice was significantly thinner than that of WT mice (49.2±2.9 vs 63.8±4.5 μm; p<0.01).
Conclusions: Our results demonstrate that impairment of SOCE in vascular SMC of PLA2g6ex2KO mice can protect these animals from age-induced arterial stiffness, suggesting its important role in this pathological process.
Author Disclosures: J.W. Shim: None. R.M. Weisbrod: None. F. Seta: None. V.M. Bolotina: None.
- © 2016 by American Heart Association, Inc.