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Coronary Vascular Cell Stiffness Influences Coronary Blood Flow
Author(s) -
Montgomery Kathlyene R.,
McCallinhart Patricia E.,
Trask Aaron J.
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.04260
Subject(s) - blood flow , cardiology , paraformaldehyde , medicine , artery , perfusion , vascular smooth muscle , actin , chemistry , anatomy , pathology , smooth muscle , biochemistry
Our laboratory has previously shown that type 2 diabetic (T2DM) coronary resistance microvessels (CRMs) undergo inward hypertrophic remodeling associated with reduced stiffness. Reduced T2DM CRM tissue stiffness is associated with decreased elastic modulus of coronary vascular smooth muscle cells (VSMCs). The goal of this study was to test the hypothesis that reducing or augmenting coronary vascular cell stiffness will increase or decrease coronary blood flow, respectively. Coronary blood flow was measured from hearts isolated from 16‐week‐old control Db/db and diabetic db/db mice and perfused on a Langendorff system at a constant pressure of 80 mmHg. Latrunculin B (1 μM final concentration; n=2 per group) was infused to depolymerize actin and reduce vascular cell stiffness and jasplakinolide (0.2 μM final concentration; n=4 per group) was infused to increase actin polymerization and increase vascular cell stiffness. After drug infusions, hearts were immediately transferred to an adjacent Langendorff apparatus and were perfusion fixed with 4% paraformaldehyde for 2 mins at 1 mL/min. Hearts were then placed in 4% PFA for 24–48 hours and were stored in 70% EtOH until embedding in paraffin and sectioning. Sections were evaluated for F‐ and G‐actin by immunofluorescence. In pooled Db/db and db/db analyses, Latrunculin B caused an increase in coronary blood flow over baseline (34.1 ± 15.0% above baseline, n=7), and jasplakinolide caused a 26.5 ± 4.1% reduction in coronary blood flow from baseline (n=8). Immunohistochemical analysis confirmed a decreased trend in F/G actin in the coronary microvessels of latrunculin B‐perfused hearts (1.00 vs. 0.82 ± 0.08, n=1–4 per group), while F/G actin tended to be increased in the CRMs of jasplakinolide‐perfused hearts (1.00 ± 0.00 vs. 1.50 ± 0.16, p =0.12, n=2–6 per group). Importantly, the F/G actin ratio in jasplakinolide‐treated hearts was not different measured in the myocardium 50–100 μm away from a CRM (1.00 ± 0.06 in vehicle‐perfused hearts vs. 1.01 ± 0.10 in jasplakinolide‐perfused hearts, p =0.96, n=2–6 per group), demonstrating that the drug was efficacious only in the peri‐vascular region. These data support the hypothesis that coronary blood flow increases as vascular cell stiffness is decreased and coronary blood flow decreases as vascular cell stiffness is increased. Collectively, these data suggest that coronary vascular cell stiffness can modulate coronary blood flow. Support or Funding Information KRM was supported by an American Heart Association Summer Undergraduate Research Fellowship (17UFEL33420025). NIH R00HL116769, R21EB026518, and S10OD023438 to AJT.