Effect of ATP-Sensitive Potassium Channel Agonists on Ventricular Remodeling in Healed Rat Infarcts
Tsung-Ming Lee, MD, FESC*,
Mei-Shu Lin, PhD and
Nen-Chung Chang, MD, PhD, FACC ,*
* Cardiology Section, Department of Medicine, Taipei Medical University and Chi-Mei Medical Center, Tainan, Taiwan
Department of Pharmacy, National Taiwan University and Hospital, Taipei, Taiwan
Cardiology Section, Department of Medicine, Taipei Medical University and Hospital, Taipei, Taiwan.
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Figure 1 Cardiac Fibrosis at the Remote Zone
(Top) Representative sections from the remote zone with sirius red staining (red, magnification 400x) at 4 weeks after infarction. Collagen deposition within the left ventricle is reduced after administering either nicorandil (Nic) or pinacidil (Pin). The line length corresponds to 50 µm. (Bottom) Left ventricular collagen area fraction (%). Each column and bar represents mean ± standard deviation. *p < 0.007 compared with vehicle-, glibenclamide (Glib)-, Nic + Glib-, and Pin + Glib-treated groups. (A) Sham; (B) vehicle; (C) Nic; (D) Pin; (E) Glib; (F) Nic + Glib; (G) Pin + Glib; (H) rapamycin (Rap); (I) Rap + Nic; (J) Rap + Pin.
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Figure 2 Echocardiogram in Infarcted Rats
Representative M-mode image reveals a hypokinetic-to-akinetic anterior wall and left ventricular (LV) dilation in the infarcted hearts (B to J) in contrast to normal anterior wall motion in sham-operated heart (A). There are markedly dilated LV end-diastolic diameter and LV end-systolic diameter in groups treated with vehicle (B), Glib (E), Nic + Glib (F), and Pin + Glib (G) compared with those in groups treated with Nic (C) and Pin (D). Besides, infarcted rats treated with Rap (H), Rap + Nic (I), and Rap + Pin (J) showed a significant decrease of LV end-diastolic diameter and LV end-systolic diameter compared with vehicle. IVS = interventricular septum thickness; other abbreviations as in Figure 1.
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Figure 4 Immunohistochemical Microscopy of p70S6 Kinase at the BZ in Different Treated Rats
Positive staining for phospho-p70S6 kinase (p70S6 kinase) (magnification 200x) (brown color) in myocytes is significantly higher in groups treated with vehicle (B), glibenclamide (E), and a combination of nicorandil + glibenclamide (F) and pinacidil + glibenclamide (G) than those in sham (A), nicorandil- (C), pinacidil- (D), rapamycin- (H), rapamycin + nicorandil- (I), and rapamycin + pinacidil–treated rats (J). The line length corresponds to 200 µm. BZ = border zone.
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Figure 5 Western Blot of Phospo-p70S6 Kinase and Total p70S6 Kinase in an In Vivo Study
(Top) Western blot analysis of p70S6 kinase showing the effect of KATP channels on immunorecognition of p70S6 kinase in homogenates of the LV from the border zone. p70S6 kinase activity was measured with phospho-specific antibody against phosphorylated p70S6 kinase (top band) and a total p70S6 kinase antibody (bottom band). Ventricular remodeling after myocardial infarction was associated with marked increase of phospho-p70S6 kinase. A significantly reduced phospho-p70S6 kinase had taken place in the groups treated with either nicorandil or pinacidil administration compared with that seen in vehicle. (Bottom) Densitometric quantification of phosphorylation levels was expressed as the ratio of the density of phosphorylated band over total p70S6 kinase. Each point is an average of 3 separate experiments. *p < 0.007 compared with vehicle-, Glib-, Nic + Glib-, and Pin + Glib–treated groups. Abbreviations as in Figure 1.
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Figure 6 Western Blot of Phospo-p70S6 Kinase and Total p70S6 Kinase in an In Vitro Study
(Top) Western blot analysis of p70S6 kinase to furthermore confirm the mitochondrial KATP channels on p70S6 kinase activity in homogenates of the left ventricle from the border zone in a rat isolated heart model. P70S6 kinase activity was measured with phospho-specific antibody against phosphorylated p70S6 kinase (top band) and a total p70S6 kinase antibody (bottom band). A significantly increased phospho-p70S6 kinase is noted in the groups treated with a combination of KATP channel agonists and 5-hydroxydecanoate (5-HD) compared with that seen in the groups treated with KATP channel agonists alone. (Bottom) Densitometric quantification of phosphorylation levels was expressed as the ratio of the density of phosphorylated band over total p70S6 kinase. Each point is an average of 3 separate experiments. *p < 0.007 compared with vehicle-, 5-HD-, Nic + 5-HD-, and Pin + 5-HD–treated groups. Abbreviations as in Figure 1.
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Figure 7 Western Blot of p70S6 Kinase in an In Vivo Study
Each mRNA was corrected for an mRNA level of glyceraldehyde-3-phosphate-dehydrogenase (GAPDH). Each column and bar represents mean ± standard deviation. *p < 0.007 compared with vehicle-, Glib-, Nic + Glib-, and Pin + Glib–treated groups. LV = left ventricular; other abbreviations as in Figure 1.
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p < 0.007 compared with vehicle. LV = left ventricular; 2D = 2-dimensional; other abbreviations as in Figure 1.