A: approximate area of the cardiac ventricles that was processed for immunohistochemistry analysis apical to the ligation (shaded area). B: areas within each individual section that were imaged. i, infarct; LV, left ventricle; 1, infarct border zone; 2, peri-infarct; 3, left ventricle (LV) free wall; 4, septum; 5, right ventricle free wall. C: sample image of tyrosine hydroxylase immunostaining obtained from the intact myocardium of the LV. Ci: image of the result from threshold analysis using ImageJ software, as performed on the image in C, in which the areas above the set threshold are shown in red. In sham myocardial infarction (MI) animals, the areas of the heart tissue that were imaged were similar to MI animals; however, there was no infarct. Scale bar in Ci applies also to C.
LV ejection fraction (left), diastolic area (middle), and systolic area (right) before renal denervation (RDx) or sham RDx surgery [pre-RDx, 4 wk postmyocardial infarction (MI) or sham MI surgery] and at 3 wk post-RDx or sham RDx surgery (post-RDx, 7 wk post-MI or sham MI surgery), as measured using echocardiography in the four groups. *Significant difference between MI-Sh group and sham MI groups, P < 0.05. +Significant difference between MI-RDx group and sham MI groups, P < 0.05. #Significant difference between MI-RDx group and MI-Sh group, P < 0.05. Values are expressed as means ± SE (n = 8–13). Sh-Sh, sham myocardial MI + sham RDx; MI-Sh, MI + sham RDx; Sh-RDx, sham MI + RDx; MI-RDx – MI + RDx.
Top left: Masson’s trichrome stained (MTS) section from a rat heart that underwent a MI and subsequent sham renal denervation (RDx); viable myocardium is stained red, and infarct (indicated by i) is stained blue. Top right: images of tyrosine hydroxylase (TH) immunostaining (red) in regions as indicated by A, B, C and D shown on the MTS section. A: sympathetic nerve fibers travel parallel to cardiomyocytes in the normal myocardium distant from the infarct. B: sympathetic fibers are minimally expressed in the normal myocardium of the peri-infarct region. C: sympathetic hyperinnervation was observed in the infarcted tissue of the infarct border-zone; D: sympathetic fibers were observed to penetrate deep into the infarct. E and F: wheat germ agglutinin (WGA) immunostaining (green) in the peri-infarct region of MI + sham RDx heart (E) and MI + RDx heart (F). Ei and Fi: TH immunostaining (red) in the peri-infarct region of MI + sham RDx heart (Ei) and MI + RDx heart (Fi). Eii and Fii: WGA and TH double labeling of peri-infarct region of MI + sham RDx heart (Ei) and MI + RDx heart (Fi). *Intact myocardium of the peri-infarct region; arrowhead indicates sympathetic hyperinnervation in the infarcted myocardium of the infarct border-zone. Scale bar in D applies also to A, B, and C. Scale bar in Fii applies to E, Ei, Eii, F and Fi. LV indicates left ventricle.
Sample images of TH (A–Aiii) and PGP 9.5 (B–Biii) immunostaining in the intact myocardium of the LV free wall remote from the infarct in rats that underwent a sham MI or MI and RDx or RDx. Sample images for sham MI + sham RDx (Sh-Sh: A and B), MI + sham RDx (MI-Sh: Ai and Bi), sham MI + RDx (Sh-RDx: Aii and Bii) and MI + RDx (MI-RDx: Aiii and Biii). Sympathetic innervation (TH; C) and total innervation (PGP 9.5; D) was quantified in the intact myocardium remote from the infarct in the left-ventricle (LV) free wall, septum, and right ventricle free wall as a percentage (%) of total area. Values are expressed as means ± SE. *Significantly different between groups, P = 0.01 < 0.05. **Significant difference between groups, P < 0.01. Scale bar: Biii applies to A, Ai, Aii, Aiii, B, Bi, and Bii.
Cardiomyocyte size and collagen content in the left ventricle (LV) in relation to treatment group. Hematoxylin and eosin (H&E)-stained cardiomyocytes (top left) and MTS-stained LV tissue (top right) for animals that underwent either sham MI or MI and sham RDx or RDx. Sample images for H&E staining for sham MI + sham RDx (Sh-Sh: A), MI + sham RDx (MI-Sh: Ai) sham MI + RDx (Sh-RDx: B) and MI + RDx (MI-RDx: Bi). Example images for MTS staining for sham MI + sham RDx (Sh-Sh: C), MI + sham RDx (MI-Sh: Ci) sham MI + RDx (Sh-RDx: D) and MI + RDx (MI-RDx: Di). Mean cardiomyocyte size and collagen content, as a percentage (%) of total area, in the free wall of the LV, septum, and right ventricle across experimental groups are shown in bar graphs. *Significant difference between groups, P = 0.01 < 0.05. **Significant difference between groups, P < 0.01. Values are expressed as means ± SE (n = 4–6). Scale bar in Bi applies also to A, Ai, and B, and scale bar in Di applies also to C, Ci, and D.
Values are expressed as means ± SE. bpm, beats per minute; LV, left ventricle; LVEDP, left ventricular end-diastolic pressure; BW, body weight; dP/dtmax, maximal left ventricular rate of pressure over time; dP/dtmin, minimal left ventricular rate of pressure over time; MI, myocardial infarction; RDx, renal denervation; Sh-Sh, sham myocardial MI+sham RDx; MI-Sh, MI+sham RDx; Sh-RDx, sham MI+RDx; MI-RDx, MI+RDx.
↵* Significant difference from Sh-Sh group, P < 0.05.