Overexpression of GRK2 in vascular smooth muscle leads to inappropriate hypertension and acute heart failure as in clinical scenario 1

Figures

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  Figure 1. Expression of the GRK2 transgene. (A) Expression of the Grk2 transgene was determined by real-time PCR in the control (n = 12) and GRK2 groups (n = 11). (B) Representative immunohistochemical staining images of in vivo protein GRK2 levels in aortas from mice in both groups. Results are expressed as mean ± SEM. GRK2 G protein-coupled receptor kinase 2, rRNA ribosomal RNA, ns not significant. *P < 0.05, ***P < 0.001.

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  Figure 2. Baseline blood pressure and heart rate. (A) and (B) Baseline resting SBP, MAP, DBP and HR in the control (n = 13) and GRK2 (n = 12) groups. Results are expressed as mean ± SEM. Comparisons of parameters were performed using the 2-tailed Student t test or Welch test. DBP diastolic blood pressure, GRK2 G protein-coupled receptor kinase 2, HR heart rate, MAP mean arterial pressure, SBP systolic blood pressure, ns not significant. *P < 0.05.

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  Figure 3. Blood pressure and heart rate pre and post either epinephrine or saline injection. SBP (A), MAP (B), DBP (C) and HR (D) in the control (n = 13) and GRK2 (n = 12) groups. (E) Ratio of pulmonary edema to body weight (Fluid in the lungs/BW) in the control (n = 12) and GRK2 (n = 11) groups. Results are expressed as mean ± SEM. Comparisons of parameters were performed using either the 2-tailed Student t test or Welch test, and repeated-measures 2-way ANOVA was used for multiple comparisons. BW body weight, DBP diastolic blood pressure, GRK2 G protein-coupled receptor kinase 2, HR heart rate, MAP mean arterial pressure, rRNA ribosomal RNA, SBP systolic blood pressure, ns not significant. *P < 0.05, **P < 0.01, ***P < 0.001.

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  Figure 4. Elevation of Nppb and LVEF was preserved in GRK2 overexpressing mice after epinephrine injection. (A) Left ventricular Nppb mRNA expression levels in the control (n = 10) and GRK2 (n = 7) groups. (B) Ratio of heart weight to body weight (HW/BW) in the control (n = 10) and GRK2 (n = 7) groups. (C) Percentage of LVEF in the control (n = 10) and GRK2 (n = 7) groups. (D) Representative Masson’s trichrome stain images in small coronary arteries in the myocardium of the left ventricle from mice in both groups. Results are expressed as mean ± SEM. Comparisons of parameters were performed using the 2-tailed Student t test or Welch test. Nppb natriuretic peptide B, BW body weight, GRK2 G protein-coupled receptor kinase 2, HW heart weight, LVEF left ventricular ejection fraction, rRNA ribosomal RNA, ns not significant. *P < 0.05.

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  Figure 5. GRK2 overexpression inhibited vasodilation at the molecular level. The control (n = 13) and the GRK2 (n = 12) groups were exposed to saline or epinephrine respectively. (A) Schematic representation of the underlying mechanism of VSM contraction induced by epinephrine administration in the control and GRK2 groups. (B) Expression of the Mlc2 transgene determined by real-time PCR. (C) Representative images of pMLC2 immunofluorescent staining in the descending aorta. Scale bar = 100 μm. (D) Quantification of pMLC2 positive areas. Data are represented as means ± SEM. α-AR alpha-adrenergic receptor, β-AR beta-adrenergic receptor, cAMP cyclic adenosine monophosphate, GRK2 G protein-coupled receptor kinase 2, IP3 inositol triphosphate, MLC2 myosin light chain 2, MLCK myosin light chain kinase, MLCP myosin light chain phosphatase, PKA protein kinase A, pMLC2 phosphorylated myosin light chain 2, rRNA ribosomal RNA, VSM vascular smooth muscle, ns not significant. **P < 0.01.