Expression and localization of angiotensin subtype receptor proteins in the hypertensive rat heart

2000 ◽  
Vol 278 (3) ◽  
pp. R781-R789 ◽  
Author(s):  
Ryoji Ozono ◽  
Toshiyuki Matsumoto ◽  
Tetsuji Shingu ◽  
Tetsuya Oshima ◽  
Yasuhiro Teranishi ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Cellular Localization ◽  
Ventricular Myocytes ◽  
Vascular Endothelial Cells ◽  
Weight Ratio ◽  
Muscle Layer ◽  
Left Ventricular ◽  
Receptor Protein ◽  
Significant Difference ◽  
Wistar Kyoto

The cellular localization of the AT2 receptor and the regulation of its expression in hypertrophied left ventricle are not well known. We compared the expression of the cardiac AT1 and AT2 receptor in spontaneously hypertensive rats/Izumo strain (SHR/Izm) and Wistar Kyoto rats/Izumo strain (WKY/Izm), ages 4, 12, and 20 wk, by means of immunohistochemistry and Western blot analysis. In SHR/Izm, compared with WKY/Izm, blood pressure (161 ± 2 vs. 120 ± 2 mmHg at 12 wk, P ≤ 0.01, and 199 ± 3 vs. 123 ± 3 mmHg at 20 wk, P≤ 0.01) and heart-to-body weight ratio (3.76 ± 0.07 vs. 3.06 ± 0.06 mg/g at 12 wk, P ≤ 0.01, and 3.90 ± 0.08 vs. 3.01 ± 0.12 mg/g at 20 wk, P ≤ 0.01) were significantly elevated. There was no difference in these values between the two strains at 4 wk of age. Histologically, 20-wk-old SHR/Izm demonstrated myocardial hypertrophy, a thickening of the smooth muscle layer of the intracardiac arteries, and perivascular fibrosis. By immunohistochemistry, the AT2 receptor was localized to cardiomyocytes and vascular endothelial cells, but not in the vascular smooth muscle cells. No major AT2 receptor signal was observed in perivascular fibrosis at any age in either strain of rats. No difference was detected in this localization between the two strains. By Western blotting, a single 44-kDa band for the AT2 receptor and a single 60-kDa band for the AT1 receptor were detected in ventricles from both strains of rats at all ages. Densitometric analysis demonstrated that the AT2 receptor 44-kDa band was decreased by 20% at 12 wk and 32% at 20 wk ( P < 0.01) in SHR/Izm compared with WKY/Izm. The intensity of the AT1 receptor 60-kDa band was increased by 57% in 20-wk-old SHR/Izm compared with WKY/Izm ( P < 0.05). There was no significant difference in the intensity of the 44- or 60-kDa bands in 4-wk-old animals of either strain. We demonstrated a decrease in the AT2 receptor and an increase in the AT1 receptor protein with no change in their localizations in hypertrophied left ventricular myocytes of SHR/Izm.

ANG II receptors, c-myc, and c-jun in myocytes after myocardial infarction and ventricular failure

1993 ◽  
Vol 264 (3) ◽  
pp. H760-H769 ◽  
Author(s):  
K. Reiss ◽  
J. M. Capasso ◽  
H. E. Huang ◽  
L. G. Meggs ◽  
P. Li ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Cardiac Hypertrophy ◽  
Right Ventricular ◽  
Ventricular Myocytes ◽  
Weight Ratio ◽  
Fold Increase ◽  
Left Ventricular ◽  
Receptor Protein ◽  
Ang Ii ◽  
Ventricular Failure

To determine the relationship between reactive cardiac hypertrophy and the expression of angiotensin II (ANG II) receptors in surviving myocytes after infarction, large infarcts were produced in rats that were killed 2–3 days later. Measurements of global ventricular dynamics indicated that left ventricular failure and right ventricular dysfunction occurred in experimental animals. These alterations in ventricular pump function were associated with increases in ventricular weight-to-body weight ratio, indicative of developing cardiac hypertrophy. Such a response was coupled with a 6.6-fold increase in ANG II receptor mRNA in myocytes from the left ventricle. A 2.3-fold increase in the expression of ANG II receptor in myocytes from the right ventricle was also found. Radioligand binding assay documented a 44% increase in the density of ANG II receptors on left ventricular myocytes of infarcted hearts. To establish whether the induction of genes commonly associated with myocyte hypertrophy was present, the message for c-myc and c-jun was biventricularly assessed. Myocardial infarction was accompanied by overexpressions of c-myc and c-jun that were more prominent in left than in right ventricular myocytes. In conclusion, the enhanced expression of ANG II receptor and its receptor protein and c-myc and c-jun in myocytes may participate in the reactive growth processes of these cells after infarction.

Effects of forskolin on inotropic performance and phospholamban phosphorylation in exercise-trained hypertensive myocardium

2007 ◽  
Vol 102 (2) ◽  
pp. 628-633 ◽  
Author(s):  
Stephen C. Kolwicz ◽  
Hajime Kubo ◽  
Scott M. MacDonnell ◽  
Steven R. Houser ◽  
Joseph R. Libonati
Keyword(s):  
Heart Rate ◽  
Adenylyl Cyclase ◽  
Spontaneously Hypertensive Rat ◽  
Weight Ratio ◽  
Left Ventricular ◽  
Treadmill Running ◽  
Chronic Hypertension ◽  
Wistar Kyoto ◽  
Developed Pressure ◽  
Phospholamban Phosphorylation

β-Adrenergic receptor (β-AR) responsiveness is downregulated in left ventricular (LV) hypertrophy induced by chronic hypertension. While exercise training in hypertension enhances β-AR responsiveness, the role of adenylyl cyclase remains unclear. The purpose of the present study was to test whether treadmill running in the spontaneously hypertensive rat (SHR) model improves LV responsiveness to forskolin (FOR) or the combination of FOR + isoproterenol (FOR+ISO). Female SHR (16-wk) were randomly placed into sedentary (SHR-SED; n = 7) or treadmill-trained (SHR-TRD; n = 8) groups. Wistar-Kyoto (WKY; n = 7) animals acted as normotensive controls. Langendorff, isovolumic LV performance was established at baseline and during incremental FOR infusion (1 and 5 μmol/l) and FOR+ISO (5 μmol/l + 1×10−8 mol/l). Heart rate, systolic blood pressure, and heart-to-body weight ratio were lower in WKY relative to both SHR groups ( P < 0.05). LV performance and heart rate significantly increased in all groups to a similar extent with incremental FOR infusion. However, in the presence of 5 μmol/l FOR, ISO increased LV developed pressure, positive change in LV pressure, and negative change in LV pressure to a greater extent in SHR-TRD relative to SHR-SED ( P < 0.05). Phospholamban phosphorylation at the Thr17 was greater in SHR-TRD relative to SHR-SED and WKY ( P < 0.05). Absolute LV developed pressure was moderately correlated with phospholamban phosphorylation at both the Ser16 ( r = 0.64; P < 0.05) and Thr17 ( r = 0.52; P < 0.05). Our data suggest that the adenylyl cyclase step in the β-AR cascade is not downregulated in the early course of hypertension and that the enhanced β-AR responsiveness with training is likely mediated at levels other than adenylyl cyclase. Our data also suggest that β-AR inotropic responsiveness in the presence of direct adenylyl cyclase agonism is improved in trained compared with sedentary SHR hearts.

Cellular distribution of GPR14 and the positive inotropic role of urotensin II in the myocardium in adult rat

2004 ◽  
Vol 97 (6) ◽  
pp. 2228-2235 ◽  
Author(s):  
Hui Gong ◽  
Yan-Xia Wang ◽  
Yi-Zhun Zhu ◽  
Wen-Wei Wang ◽  
Ming-Jie Wang ◽  
...  
Keyword(s):  
Rat Heart ◽  
Cellular Localization ◽  
Cardiac Myocyte ◽  
Left Ventricular ◽  
Receptor Protein ◽  
Cellular Distribution ◽  
Urotensin Ii ◽  
Double Staining ◽  
Cell Type ◽  
Rt Pcr

Urotensin II is a cyclic neuropeptide recently shown to play a role via its receptor GPR14 in regulating vascular tone in the mammalian cardiovascular system. The existence of GPR14 in rat heart has been validated by ligand binding assay and RT-PCR. In the present study, we investigated the cellular distribution of GPR14 protein in rat heart by using immunohistochemistry and confocal microscopic immunofluorescence double staining with antipeptide polyclonal antibodies against GPR14 and cell type markers for myocytes and endothelial cells. The direct effect of urotensin II on left ventricular contractility was further evaluated in isolated left ventricular papillary muscles of the rat. In paraffin-embedded heart sections, positive immunohistochemical staining was observed in the left ventricle but not in the right ventricle and atria. Immunofluorescence double staining revealed the cardiac myocyte as the only cell type expressing GPR14 protein in frozen heart sections as well as in isolated cardiac myocytes. There was no visible signal for GPR14 in intramyocardial coronary arteries and capillaries. The existence of GPR14 protein in rat heart was further validated by immunoprecipitation and Western blot analysis. In isolated rat left ventricular papillary muscle preparations, urotensin II induced an increase in active contractile force. GPR14 mRNA was also detected in rat heart by RT-PCR. These data provide the first direct evidence for the cellular localization of GPR14 receptor protein and a positive inotropic effect of urotensin II in normal rat heart.

Troponin I phosphorylation in spontaneously hypertensive rat heart: effect of beta-adrenergic stimulation

1997 ◽  
Vol 273 (3) ◽  
pp. H1440-H1451 ◽  
Author(s):  
B. K. McConnell ◽  
C. S. Moravec ◽  
I. Morano ◽  
M. Bond
Keyword(s):  
Troponin I ◽  
Ventricular Myocytes ◽  
Spontaneously Hypertensive Rat ◽  
Left Ventricular ◽  
Adrenergic Stimulation ◽  
Beta Adrenergic ◽  
Spontaneously Hypertensive ◽  
Myosin Light Chain 2 ◽  
Wistar Kyoto ◽  
Phospholamban Phosphorylation

We compared baseline and protein kinase A (PKA)-dependent troponin I (TnI) phosphorylation in 32Pi-labeled left ventricular myocytes from hearts of 26-wk spontaneously hypertensive rats (SHR) and Wistar-Kyoto controls (WKY). TnI phosphorylation was normalized to myosin light chain 2 phosphorylation, which was invariant. There was no difference in baseline TnI phosphorylation in SHR and WKY, but stimulation with isoproterenol, norepinephrine plus prazosin, forskolin, chloroadenosine 3',5'-cyclic monophosphate, or 3-isobutyl-1-methylxanthine caused a greater increase in TnI phosphorylation in the SHR than in the WKY. This was observed both in the presence and absence of the phosphatase inhibitor calyculin A; thus the differences in TnI phosphorylation between SHR and WKY are not due to decreased phosphatase activity in the SHR. After stimulation of the beta-adrenergic pathway, phospholamban phosphorylation was not different in SHR and WKY, indicating that the observed differences may be specific for PKA phosphorylation of TnI. The increased PKA-dependent TnI phosphorylation in the SHR resulted in decreased Ca2+ sensitivity of actomyosin adenosinetriphosphatase activity as compared with the WKY. We conclude that increased PKA-dependent TnI phosphorylation in the SHR may contribute to the impaired response to sympathetic stimulation.

Reduced peribronchial fibrosis in allergen-challenged MMP-9-deficient mice

2006 ◽  
Vol 291 (2) ◽  
pp. L265-L271 ◽  
Author(s):  
Dae Hyun Lim ◽  
Jae Youn Cho ◽  
Marina Miller ◽  
Kirsti McElwain ◽  
Shauna McElwain ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Airway Remodeling ◽  
Muscle Thickness ◽  
Muscle Layer ◽  
Airway Responsiveness ◽  
Wild Type ◽  
Extracellular Proteases ◽  
Significant Difference ◽  
Deficient Mice ◽  
Modest Reduction

Matrix metalloproteinases (MMPs) are a family of extracellular proteases that are responsible for the degradation of the extracellular matrix during tissue remodeling. We have used a mouse model of allergen-induced airway remodeling to determine whether MMP-9 plays a role in airway remodeling. MMP-9-deficient and wild-type (WT) mice were repetitively challenged intranasally with ovalbumin (OVA) antigen to develop features of airway remodeling including peribronchial fibrosis and increased thickness of the peribronchial smooth muscle layer. OVA-challenged MMP-9-deficient mice had less peribronchial fibrosis and total lung collagen compared with OVA-challenged WT mice. There was no reduction in mucus expression, smooth muscle thickness, or airway responsiveness in OVA-challenged MMP-9-deficient compared with OVA-challenged WT mice. OVA-challenged MMP-9-deficient mice had reduced levels of bronchoalveolar lavage (BAL) regulated on activation, normal T cell expressed, and secreted (RANTES), as well as reduced numbers of BAL and peribronchial eosinophils compared with OVA-challenged WT mice. There were no significant difference in levels of BAL eotaxin, thymus- and activation-regulated chemokine (TARC), or macrophage-derived chemokine (MDC) in OVA-challenged WT compared with MMP-9-deficient mice. Overall, this study demonstrates that MMP-9 may play a role in mediating selected aspects of allergen-induced airway remodeling (i.e., modest reduction in levels of peribronchial fibrosis) but does not play a significant role in mucus expression, smooth muscle thickness, or airway responsiveness.

scholarly journals Cellular localization and structural characterization of natriuretic peptide-expressing ventricular myocytes from patients with dilated cardiomyopathy.

1994 ◽  
Vol 42 (9) ◽  
pp. 1207-1214 ◽  
Author(s):  
M Tanaka ◽  
M Hiroe ◽  
T Nishikawa ◽  
T Sato ◽  
F Marumo
Keyword(s):  
In Situ Hybridization ◽  
Dilated Cardiomyopathy ◽  
Natriuretic Peptide ◽  
Natriuretic Peptides ◽  
Cellular Localization ◽  
Structural Changes ◽  
Ventricular Myocytes ◽  
Left Ventricular

Although atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are expressed in the tissue of ventricles of failing hearts, the localization and histopathological features of natriuretic peptide-expressing ventricular myocytes have not been clearly described. This study was designed to characterize the ventricular cardiomyocytes that express both natriuretic peptides in 19 patients with dilated cardiomyopathy (DCM). Immunohistochemistry and in situ hybridization for ANP and BNP were performed with left ventricular biopsy specimens. Peptide-expressing myocytes were examined by hematoxylin-eosin staining and desmin immunohistochemistry and by in situ hybridization to characterize the corresponding cells histopathologically. The distribution of ANP- and BNP-expressing myocytes in the ventricle was identical and was located in the subendocardial layer, fibrous area, and perivascular region. Desmin was found in heavy deposits in the cytosol of peptide-expressing myocytes, and desmin mRNA was not always augmented in the peptide-expressing myocytes. These results indicate that the augmented expression of natriuretic peptides in the left ventricle of patients with DCM is not due solely to global stress on the ventricular wall but is also influenced by regional conditions and is associated with structural changes in the myocytes.

Calcineurin inhibition normalizes β-adrenergic responsiveness in the spontaneously hypertensive rat

2007 ◽  
Vol 293 (5) ◽  
pp. H3122-H3129 ◽  
Author(s):  
Scott M. MacDonnell ◽  
Hajime Kubo ◽  
David M. Harris ◽  
Xiongwen Chen ◽  
Remus Berretta ◽  
...  
Keyword(s):  
Spontaneously Hypertensive Rat ◽  
Cardiac Contractility ◽  
Weight Ratio ◽  
Left Ventricular ◽  
Heart Weight ◽  
Adrenergic Stimulation ◽  
Spontaneously Hypertensive ◽  
Wistar Kyoto ◽  
Calcineurin Activity ◽  
Calcineurin Inhibition

Calcineurin, a Ca2+-regulated protein phosphatase, links myocardial Ca2+ signaling with hypertrophic gene transcription. Calcineurin abundance increases in pressure-overload hypertrophy and may reduce agonist-mediated phospholamban (PLB) phosphorylation to underlie blunted β-adrenergic receptor (β-AR) responsiveness in hypertension. This hypothesis was tested by measuring the effects of calcineurin inhibition on changes in cardiac contractility caused by β-adrenergic stimulation in spontaneously hypertensive rats (SHR). Female SHR (age: 7 mo) and age-matched female Wistar-Kyoto rats (WKY) were studied. Heart weight-to-body weight ratio ( P < 0.01) and systolic blood pressure ( P < 0.01) were greater in SHR compared with WKY and were associated with increased myocardial calcineurin mRNA (CnAβ) and activity ( P < 0.05). β-AR stimulation with isoproterenol (Iso) increased calcineurin activity ( P < 0.05) in both WKY and SHR hearts, and this activity was suppressed with cyclosporin A (CsA) treatment. In SHR, CsA improved left ventricular whole heart and isolated myocyte β-AR responsiveness by normalizing PLB phosphorylation at Ser16 and Thr17 ( P < 0.05). These CsA-induced, PLB-mediated effects were associated with an augmentation in cardiomyocyte peak Ca2+ and a reduced rate (time constant of isovolumic pressure relaxation, tau) and magnitude of diastolic Ca2+ during β-AR stimulation. In conclusion, CsA normalized the blunted β-AR responsiveness associated with hypertension, in part, by mitigating calcineurin activity while improving PLB phosphorylation and subsequent sarcoplasmic reticulum Ca2+ regulation.

scholarly journals Decreased Ca2+ extrusion via Na+/Ca2+ exchange in epicardial left ventricular myocytes during compensated hypertrophy

2005 ◽  
Vol 288 (5) ◽  
pp. H2431-H2438 ◽  
Author(s):  
Mark R. Fowler ◽  
James R. Naz ◽  
Mark D. Graham ◽  
Gilles Bru-Mercier ◽  
Simon M. Harrison ◽  
...  
Keyword(s):  
Time Course ◽  
Ventricular Myocytes ◽  
Major Change ◽  
Left Ventricular ◽  
Spontaneously Hypertensive ◽  
Cellular Hypertrophy ◽  
Time To Peak ◽  
Intracellular Ca ◽  
The Face ◽  
Wistar Kyoto

Hypertension-induced cardiac hypertrophy alters the amplitude and time course of the systolic Ca2+ transient of subepicardial and subendocardial ventricular myocytes. The present study was designed to elucidate the mechanisms underlying these changes. Myocytes were isolated from the left ventricular subepicardium and subendocardium of 20-wk-old spontaneously hypertensive rats (SHR) and age-matched normotensive Wistar-Kyoto rats (WKY; control). We monitored intracellular Ca2+ using fluo 3 or fura 2; caffeine (20 mmol/l) was used to release Ca2+ from the sarcoplasmic reticulum (SR), and Ni2+ (10 mM) was used to inhibit Na+/Ca2+ exchange (NCX) function. SHR myocytes were significantly larger than those from WKY hearts, consistent with cellular hypertrophy. Subepicardial myocytes from SHR hearts showed larger Ca2+ transient amplitude and SR Ca2+ content and less Ca2+ extrusion via NCX compared with subepicardial WKY myocytes. These parameters did not change in subendocardial myocytes. The time course of decline of the Ca2+ transient was the same in all groups of cells, but its time to peak was shorter in subepicardial cells than in subendocardial cells in WKY and SHR and was slightly prolonged in subendocardial SHR cells compared with WKY subendocardial myocytes. It is concluded that the major change in Ca2+ cycling during compensated hypertrophy in SHR is a decrease in NCX activity in subepicardial cells; this increases SR Ca2+ content and hence Ca2+ transient amplitude, thus helping to maintain the strength of contraction in the face of an increased afterload.

Stage-dependent changes in membrane currents in rats with monocrotaline-induced right ventricular hypertrophy

1997 ◽  
Vol 272 (6) ◽  
pp. H2833-H2842 ◽  
Author(s):  
J. K. Lee ◽  
I. Kodama ◽  
H. Honjo ◽  
T. Anno ◽  
K. Kamiya ◽  
...  
Keyword(s):  
Action Potential ◽  
Ventricular Hypertrophy ◽  
Ventricular Myocytes ◽  
Early Stage ◽  
Weight Ratio ◽  
Outward Current ◽  
Transient Outward Current ◽  
Significant Difference ◽  
And Control ◽  
Action Potential Configuration

Sequential changes in action potential configuration, 4-amino-pyridine-sensitive transient outward current (Ito), and L-type calcium current (ICa) in association with hypertrophy were investigated in ventricular myocytes from rats with monocrotaline (MCT)-induced pulmonary hypertension. The tissue weight ratio of right ventricle (RV) to left ventricle plus septum 14 and 28 days after a subcutaneous injection of MCT increased by 29.7 and 77.2%, respectively. Action potential duration (APD) of RV cells from MCT rats increased progressively, prolonged by 73.2 and 92.2% on days 14 and 28, respectively. The current density of Ito in RV cells from MCT rats on day 14 (32.5 +/- 4.5 pA/pF, n = 13) was significantly larger than in controls (26.8 +/- 4.5 pA/pF, n = 8; P < 0.05). On day 28, however, Ito density in MCT rats (15.3 +/- 4.6 pA/pF, n = 9) was significantly less than in controls (27.3 +/- 4.2 pA/pF, n = 10; P < 0.05). There were no differences in the voltage dependence of steady-state activation and inactivation of Ito between MCT and control rats. ICa density in MCT rats on day 14 (15.7 +/- 2.6 pA/pF, n = 10) was significantly larger than in controls (10.0 +/- 2.3 pA/pF, n = 10; P < 0.05), but there was no significant difference in Ito density between MCT rats (8.3 +/- 3.7 pA/pF, n = 10) and controls (11.6 +/- 3.0 pA/pF, n = 10) on day 28. These findings suggest that hypertrophy of mammalian hearts may cause stage-dependent changes in Ito and ICa density of ventricular myocytes. The APD prolongation in the early stage of hypertrophy may be caused mainly by an increase in ICa density, whereas the APD prolongation in the late stage may be ascribed to a reduction in Ito density.

Sign in / Sign up

Export Citation Format

Share Document