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.

Chronic urotensin-II infusion induces diastolic dysfunction and enhances collagen production in rats

2010 ◽  
Vol 298 (2) ◽  
pp. H608-H613 ◽  
Author(s):  
Lavinia Tran ◽  
Andrew R. Kompa ◽  
Will Kemp ◽  
Arintaya Phrommintikul ◽  
Bing H. Wang ◽  
...  
Keyword(s):  
Diastolic Dysfunction ◽  
Intracellular Signaling ◽  
Cardiac Myocyte ◽  
Collagen Type I ◽  
Left Ventricular ◽  
High Dose ◽  
Type I ◽  
Urotensin Ii ◽  
Rock Inhibitor

The vasoactive peptide urotensin-II (U-II) is likely to play a key causal role in cardiac remodeling that ultimately leads to heart failure. Its contribution, specifically to the development of diastolic dysfunction and the downstream intracellular signaling, however, remains unresolved. This study interrogates the effect of chronic U-II infusion in normal rats on cardiac structure and function. The contribution of Rho kinase (ROCK) signaling to these pathophysiological changes is evaluated in cell culture studies. Chronic high-dose U-II infusion over 4 wk significantly impaired diastolic function in rats on echocardiography-derived Doppler indexes, including E-wave deceleration time (vehicle 56.7 ± 3.3 ms, U-II 118.0 ± 21.5 ms; P < 0.01) and mitral valve annulus peak early/late diastolic tissue velocity (vehicle 2.01 ± 0.19 ms, U-II 1.04 ± 0.25 ms; P < 0.01). A lower dose of U-II infusion (1 nmol·kg−1·h−1) yielded comparable changes. Diastolic dysfunction was accompanied by molecular [significant increases in procollagen-α1(I) gene expression on real-time PCR] and morphological (increases in total collagen, P < 0.05, and collagen type-I protein deposition, P < 0.001) evidence of left ventricular (LV) fibrosis following high-dose U-II infusion. The ROCK inhibitor GSK-576371 (10−7 to 10−5 M) elicited concentration-dependent inhibition of U-II (10−7 M)-stimulated cardiac fibroblast collagen synthesis and cardiac myocyte protein synthesis. Chronic U-II infusion causes diastolic dysfunction, caused by fibrosis of the LV. The in vitro data suggest that this may be in part occurring via a ROCK-dependent pathway.

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.

Parathyroid Ca2+-conducting currents are modulated by muscarinic receptor agonists and antagonists

1997 ◽  
Vol 273 (5) ◽  
pp. E880-E890 ◽  
Author(s):  
Wenhan Chang ◽  
Tsui-Hua Chen ◽  
Stacy A. Pratt ◽  
Benedict Yen ◽  
Michael Fu ◽  
...  
Keyword(s):  
Muscarinic Receptors ◽  
Inositol Phosphate ◽  
Receptor Protein ◽  
Dependent Manner ◽  
Rt Pcr ◽  
Pipette Solution ◽  
Pcr Products ◽  
Inositol Phosphate Accumulation ◽  
Receptor Cdna ◽  
Dose Dependent

Parathyroid cells express Ca2+-conducting cation currents, which are activated by raising the extracellular Ca2+ concentration ([Ca2+]o) and blocked by dihydropyridines. We found that acetylcholine (ACh) inhibited these currents in a reversible, dose-dependent manner (50% inhibitory concentration ≈10−8 M). The inhibitory effects could be mimicked by the agonist (+)-muscarine. The effects of ACh were blunted by the antagonist atropine and reversed by removing ATP from the pipette solution. (+)-Muscarine enhanced the adenosine 3′,5′-cyclic monophosphate (cAMP) production by 30% but had no effect on inositol phosphate accumulation in parathyroid cells. Oligonucleotide primers, based on sequences of known muscarinic receptors (M1-M5), were used in reverse transcriptase-polymerase chain reaction (RT-PCR) to amplify receptor cDNA from parathyroid poly (A)+ RNA. RT-PCR products displayed >90% nucleotide sequence identity to human M2- and M4-receptor cDNAs. Expression of M2-receptor protein was further confirmed by immunoblotting and immunocytochemistry. Thus parathyroid cells express muscarinic receptors of M2 and possibly M4 subtypes. These receptors may couple to dihydropyridine-sensitive, cation-selective currents through the activation of adenylate cyclase and ATP-dependent pathways in these cells.

Dobutamine responsiveness, PET mismatch, and lack of necrosis in low-flow ischemia: is this hibernation in the isolated rat heart?

2003 ◽  
Vol 285 (1) ◽  
pp. H316-H324 ◽  
Author(s):  
Richard Southworth ◽  
Pamela B. Garlick
Keyword(s):  
Rat Heart ◽  
Recovery Of Function ◽  
Electron Microscopic Examination ◽  
Left Ventricular ◽  
Isolated Rat Heart ◽  
Low Flow ◽  
Hibernating Myocardium ◽  
Heart Model ◽  
Electron Microscopic ◽  
Isolated Rat

The clinical hallmarks of hibernating myocardium include hypocontractility while retaining an inotropic reserve (using dobutamine echocardiography), having normal or increased [18F]fluoro-2-deoxyglucose-6-phosphate (18FDG6P) accumulation associated with decreased coronary flow [flow-metabolism mismatch by positron emission tomography (PET)], and recovering completely postrevascularization. In this study, we investigated an isolated rat heart model of hibernation using experimental equivalents of these clinical techniques. Rat hearts ( n = 5 hearts/group) were perfused with Krebs-Henseleit buffer for 40 min at 100% flow and 3 h at 10% flow and reperfused at 100% flow for 30 min (paced at 300 beats/min throughout). Left ventricular developed pressure fell to 30 ± 8% during 10% flow and recovered to 90 ± 7% after reperfusion. In an additional group, this recovery of function was found to be preserved over 2 h of reperfusion. Electron microscopic examination of hearts fixed at the end of the hibernation period demonstrated a lack of ischemic injury and an accumulation of glycogen granules, a phenomenon observed clinically. In a further group, hearts were challenged with dobutamine during the low-flow period. Hearts demonstrated an inotropic reserve at the expense of increased lactate leakage, with no appreciable creatine kinase release. PET studies used the same basic protocol in both dual- and globally perfused hearts (with 250MBq18FDG in Krebs buffer ± 0.4 mmol/l oleate). PET data showed flow-metabolism “mismatch;” whether regional or global,18FDG6P accumulation in ischemic tissue was the same as (glucose only) or significantly higher than (glucose + oleate) control tissue (0.023 ± 0.002 vs. 0.011 ± 0.002 normalized counts · s-1· g-1· min-1, P < 0.05) despite receiving 10% of the flow. This isolated rat heart model of acute hibernation exhibits many of the same characteristics demonstrated clinically in hibernating myocardium.

scholarly journals Superoxide production by NAD(P)H oxidase and mitochondria is increased in genetically obese and hyperglycemic rat heart and aorta before the development of cardiac dysfunction. The role of glucose-6-phosphate dehydrogenase-derived NADPH

2009 ◽  
Vol 297 (1) ◽  
pp. H153-H162 ◽  
Author(s):  
Sabrina Serpillon ◽  
Beverly C. Floyd ◽  
Rakhee S. Gupte ◽  
Shimran George ◽  
Mark Kozicky ◽  
...  
Keyword(s):  
Cardiac Dysfunction ◽  
Rat Heart ◽  
Mitochondrial Respiratory Chain ◽  
Posterior Wall ◽  
Left Ventricular ◽  
Posterior Wall Thickness ◽  
Patients With Diabetes ◽  
Protein Kinase C Inhibitor ◽  
Glucose 6 Phosphate Dehydrogenase

Increased oxidative stress is a known cause of cardiac dysfunction in animals and patients with diabetes, but the sources of reactive oxygen species [e.g., superoxide anion (O2−)] and the mechanisms underlying O2− production in diabetic hearts are not clearly understood. Our aim was to determine whether NADPH oxidase (Nox) is a source of O2− and whether glucose-6-phosphate dehydrogenase (G6PD)-derived NADPH plays a role in augmenting O2− generation in diabetes. We assessed cardiac function, Nox and G6PD activities, NADPH levels, and the activities of antioxidant enzymes in heart homogenates from young (9–11 wk old) Zucker lean and obese (fa/fa) rats. We found that myocardial G6PD activity was significantly higher in fa/fa than in lean rats, whereas superoxide dismutase and glutathione peroxidase activities were decreased ( P < 0.05). O2− levels were elevated (70–90%; P < 0.05) in the diabetic heart, and this elevation was blocked by the Nox inhibitor gp-91ds-tat (50 μM) or by the mitochondrial respiratory chain inhibitors antimycin (10 μM) and rotenone (50 μM). Inhibition of G6PD by 6-aminonicotinamide (5 mM) and dihydroepiandrosterone (100 μM) also reduced ( P < 0.05) O2− production. Notably, the activities of Nox and G6PD in the fa/fa rat heart were inhibited by chelerythrine, a protein kinase C inhibitor. Although we detected no changes in stroke volume, cardiac output, or ejection fraction, left ventricular diameter was slightly increased during diastole and systole, and left ventricular posterior wall thickness was decreased during systole ( P < 0.05) in Zucker fa/fa rats. Our findings suggest that in a model of severe hyperlipidema and hyperglycemia Nox-derived O2− generation in the myocardium is fueled by elevated levels of G6PD-derived NADPH. Similar mechanisms were found to activate O2− production and induce endothelial dysfunction in aorta. Thus G6PD may be a useful therapeutic target for treating the cardiovascular disease associated with type 2 diabetes, if second-generation drugs specifically reducing the activity of G6PD to near normal levels are developed.

Geometrical models of left ventricular contraction from MRI of the normal and spontaneously hypertensive rat heart

1999 ◽  
Vol 44 (10) ◽  
pp. 2657-2676 ◽  
Author(s):  
Richard G Wise ◽  
Christopher L-H Huang ◽  
Ahmed I M Al-Shafei ◽  
T Adrian Carpenter ◽  
Laurance D Hall
Keyword(s):  
Rat Heart ◽  
Spontaneously Hypertensive Rat ◽  
Left Ventricular ◽  
Ventricular Contraction ◽  
Spontaneously Hypertensive ◽  
Hypertensive Rat

Abstract 1876: Functional Effect of Chronic Urotensin II Receptor Antagonist on L-Type Ca 2+ Current in Mouse Model of Progressive Heart Failure

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Peng Zhou ◽  
Heng-Jie Cheng ◽  
Michael Cross ◽  
Michael F Callahan ◽  
Bridget Brosnihan ◽  
...  
Keyword(s):  
Heart Failure ◽  
Receptor Antagonist ◽  
Weight Ratio ◽  
Heart Association ◽  
Cell Voltage ◽  
Fold Increase ◽  
Left Ventricular ◽  
Lv Function ◽  
List Type ◽  
Urotensin Ii

Voltage-gated Ca 2+ channels play fundamental roles in the regulation of cardiac function by various neurotransmitters. Recently, we have shown that urotensin II (UII), a potent vasoconstrictor, inhibits L-type Ca 2+ current (I Ca,L ) and produces negative inotropic action. In heart failure (HF), the UII-mediated pathway is upregulated, suggesting a therapeutic value of UII receptor antagonist (UII-ANT) for HF. However, the role and mechanism of chronic UII-ANT in HF is unclear. We tested the hypothesis that chronic UII-ANT may improve cardiac I Ca,L , preventing β-adrenergic deregulation on I Ca,L and limit HF progression. We examined plasma levels of norepinephrine (NE), left ventricular (LV) function, and myocyte I Ca,L responses to isoproterenol (ISO) in 3 age-matched groups of mice: HF (n = 7), 2 months after ISO (150 mg/kg sq for 2 days); HF/UII-ANT (n = 11), 1 month after receiving ISO, then urantide, a potent UII-ANT (10 −5 M/kg/day, sq via implanted osmotic mini pump), given for 1 month; and Controls (n = 7). I Ca,L was measured using whole-cell voltage clamp technique. Compared with controls, ISO-treated mice progressed to HF with 4.7-fold increase in plasma NE (18975 vs 4066 pg/ml) and LV dilatation associated with increased myocyte length (ML, 155 vs120 μm) and heart-to-body weight ratio (H/BW, 7.6 vs 5.5 g/kg). Stroke volume (SV, 30.3 vs 61.4 μl) and ejection fraction (EF, 39% vs 60%) were decreased. Compared with normal myocytes, in HF myocytes, I Ca,L was reduced (50%, 3.7 ± 0.2 vs 7.4 ± 0.2 pA/pF), and I Ca,L response to β-AR stimulation (ISO, 10 −8 M) was attenuated (11% vs 35%) (p < 0.01). In HF/UII-ANT mice, plasma NE (5148 pg/ml), SV (57.9 μl), and EF (57%) returned close to control levels with retained normal ML (124 μm) and H/BW (5.9 g/kg). Moreover, compared with controls, in HF/UII-ANT mice, ISO caused similar increases in the peak I Ca,L (32% vs 35%). Chronic UII-ANT treatment normalizes LV L-type Ca 2+ channel basal function and β-adrenergic regulation, leading to regression of LV and myocyte dysfunction and remodeling in mice with ISO-induced HF. This research has received full or partial funding support from the American Heart Association, AHA National Center.

scholarly journals AE anion exchangers in atrial tumor cells

2001 ◽  
Vol 280 (3) ◽  
pp. H937-H945 ◽  
Author(s):  
Panos Papageorgiou ◽  
Boris E. Shmukler ◽  
Alan K. Stuart-Tilley ◽  
Lianwei Jiang ◽  
Seth L. Alper
Keyword(s):  
Tumor Cell Line ◽  
Disulfonic Acid ◽  
Cell Type ◽  
Intracellular Acidification ◽  
Ph Homeostasis ◽  
Rt Pcr ◽  
Anion Exchangers ◽  
Atrial Tumor ◽  
Atrial Cell ◽  
Exchange Activity

Intracellular pH homeostasis and intracellular Cl−concentration in cardiac myocytes are regulated by anion exchange mechanisms. In physiological extracellular Cl−concentrations, Cl−/HCO[Formula: see text] exchange promotes intracellular acidification and Cl−loading sensitive to inhibition by stilbene disulfonates. We investigated the expression of AE anion exchangers in the AT-1 mouse atrial tumor cell line. Cultured AT-1 cells exhibited a substantial basal Na+-independent Cl−/HCO[Formula: see text] (but not Cl−/OH−) exchange activity that was inhibited by DIDS but not by dibenzamidostilbene disulfonic acid (DBDS). AT-1 cell Cl−/HCO[Formula: see text] activity was stimulated two- to threefold by extracellular ATP and ANG II. AE mRNAs detected by RT-PCR in AT-1 cells included brain AE3 (bAE3), cardiac AE3 (cAE3), AE2a, AE2b, AE2c1, AE2c2, and erythroid AE1 (eAE1), but not kidney AE1 (kAE1). Cultured AT-1 cells expressed AE2, cAE3, and bAE3 polypeptides, which were detected by immunoblot and immunocytochemistry. An AE1-like epitope was detected by immunocytochemistry but not by immunoblot. Both bAE3 and cAE3 were present in intact AT-1 tumors. Cultured AT-1 cells provide a useful system for the study of mediators and regulators of Cl−/HCO[Formula: see text] exchange activity in an atrial cell type.

scholarly journals Regulation and expression of a renin-angiotensin system in human pancreas and pancreatic endocrine tumours

2002 ◽  
pp. 567-572 ◽  
Author(s):  
KY Lam ◽  
PS Leung
Keyword(s):  
Renin Angiotensin System ◽  
Receptor Protein ◽  
Pancreatic Ducts ◽  
Human Pancreas ◽  
Rt Pcr ◽  
Angiotensin System ◽  
Endocrine Tumours ◽  
Renin Angiotensin ◽  
Objective Evidence ◽  
Pancreatic Endocrine Tumours

OBJECTIVE: Evidence exists for the presence of a renin-angiotensin system (RAS) in the pancreas. The aims of this study were to prove the presence of an intrinsic RAS in the human pancreas and to analyse the role of such an RAS in pancreatic endocrine tumours (PETs). METHODS: Gene expression of key RAS components (angiotensinogen and angiotensin II receptors, namely AT1 and AT2) was investigated in human pancreas and in PETs by semi-quantitative RT-PCR and immunohistochemistry. RESULTS: Expression of mRNAs of RAS components was found in human pancreas and in PETs. Data from semi-quantitative RT-PCR analysis demonstrated an increase in the mRNA expression of angiotensinogen and AT2 receptor in PETs when compared with that in normal pancreas. By immunohistochemistry, angiotensinogen protein was predominantly localized in the pancreatic islets while AT1 receptor protein was in the pancreatic ducts. CONCLUSIONS: The data support the notion of the existence of an intrinsic RAS in the human pancreas. It also indicates, for the first time, that such a local pancreatic RAS is subject to regulation by PETs and its significant change may have pathophysiological relevance in patients with PETs.

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