Cardiac muscle following quick-freezing: Preservation of in vivo ultrastructure and geometry with special emphasis on intercellular clefts in the intact frog heart

1988 ◽  
Vol 20 (4) ◽  
pp. 285-302 ◽  
Author(s):  
J SOMMER ◽  
E JOHNSON ◽  
N WALLACE ◽  
R NASSAR
Keyword(s):  
Cardiac Muscle ◽  
Frog Heart ◽  
Quick Freezing ◽  
Intercellular Clefts

Abstract 791: A Critical Role for Bmper (BMP-binding Endothelial cell precursor-derived Regulator) in Cardiac Muscle Mass Regulation during Development and Pressure Overload Induced Hypertrophy

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Monte Willis ◽  
Rongqin Ren ◽  
Cam Patterson
Keyword(s):  
Cardiac Function ◽  
Cardiac Muscle ◽  
Muscle Mass ◽  
Cardiac Development ◽  
Critical Role ◽  
Pressure Overload ◽  
Posterior Wall ◽  
Fractional Shortening

Bone morphogenetic proteins (BMPs) of the TGF-beta superfamily, have been implicated in multiple processes during cardiac development. Our laboratory recently described an unprecedented role for Bmper in antagonizing BMP-2, BMP-4, and BMP-6. To determine the role of Bmper on cardiac development in vivo, we created Bmper null (Bmper −/−) mice by replacing exons 1 and 2 with GFP. Since Bmper −/− mice are perinatally lethal, we determined pre-natal cardiac function of Bmper −/− mice in utero just before birth. By echocardiography, E18.5 Bmper −/− embryos had decreased cardiac function (24.2 +/− 8.1% fractional shortening) compared to Bmper +/− and Bmper +/+ siblings (52.2 +/− 1.6% fractional shortening) (N=4/group). To further characterize the role of Bmper on cardiac function in adult mice, we performed echocardiography on 8-week old male and female Bmper +/− and littermate control Bmper +/+. Bmper +/− mice had an approximately 15% decrease in anterior and posterior wall thickness compared to sibling Bmper +/+ mice at baseline (n=10/group). Cross-sectional areas of Bmper +/− cardiomyocytes were approximately 20% less than wild type controls, indicating cardiomyocyte hypoplasia in adult Bmper +/− mice at baseline. Histologically, no significant differences were identified in representative H&E and trichrome stained adult Bmper +/− and Bmper +/+ cardiac sections at baseline. To determine the effects of Bmper expression on the development of cardiac hypertrophy, both Bmper +/− and Bmper +/+ sibling controls underwent transaortic constriction (TAC), followed by weekly echocardiography. While a deficit was identified in Bmper +/− mice at baseline, both anterior and posterior wall thicknesses increased after TAC, such that identical wall thicknesses were identified in Bmper +/− and Bmper +/+ mice 1–4 weeks after TAC. Notably, cardiac function (fractional shortening %) and histological evaluation revealed no differences between Bmper +/− and Bmper +/+ any time after TAC. These studies identify for the first time that Bmper expression plays a critical role in regulating cardiac muscle mass during development, and that Bmper regulates the development of hypertrophy in response to pressure overload in vivo.

Cardiomyopathy in transgenic mice with cardiac-specific overexpression of serum response factor

2001 ◽  
Vol 280 (4) ◽  
pp. H1782-H1792 ◽  
Author(s):  
Xiaomin Zhang ◽  
Gohar Azhar ◽  
Jianyuan Chai ◽  
Pamela Sheridan ◽  
Koichiro Nagano ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Cardiac Muscle ◽  
Serum Response Factor ◽  
Interstitial Fibrosis ◽  
Weight Ratio ◽  
Heart Weight ◽  
Cardiomyocyte Hypertrophy ◽  
Response Factor ◽  
Serum Response

Serum response factor (SRF), a member of the MCM1, agamous, deficiens, SRF (MADS) family of transcriptional activators, has been implicated in the transcriptional control of a number of cardiac muscle genes, including cardiac α-actin, skeletal α-actin, α-myosin heavy chain (α-MHC), and β-MHC. To better understand the in vivo role of SRF in regulating genes responsible for maintenance of cardiac function, we sought to test the hypothesis that increased cardiac-specific SRF expression might be associated with altered cardiac morphology and function. We generated transgenic mice with cardiac-specific overexpression of the human SRF gene. The transgenic mice developed cardiomyopathy and exhibited increased heart weight-to-body weight ratio, increased heart weight, and four-chamber dilation. Histological examination revealed cardiomyocyte hypertrophy, collagen deposition, and interstitial fibrosis. SRF overexpression altered the expression of SRF-regulated genes and resulted in cardiac muscle dysfunction. Our results demonstrate that sustained overexpression of SRF, in the absence of other stimuli, is sufficient to induce cardiac change and suggest that SRF is likely to be one of the downstream effectors of the signaling pathways involved in mediating cardiac hypertrophy.

Cardiac muscle diseases in genetically engineered mice: evolution of molecular physiology

1995 ◽  
Vol 269 (3) ◽  
pp. H755-H766 ◽  
Author(s):  
K. R. Chien
Keyword(s):  
Cardiac Muscle ◽  
Large Body ◽  
Genetically Engineered ◽  
Mouse Genetics ◽  
Model Systems ◽  
Molecular Physiology ◽  
Muscle Diseases ◽  
Recent Advances ◽  
Genetically Engineered Mice

Recent advances in molecular, cellular, and genetically based technologies now offer the possibility of generating genetically engineered mice that display physiological phenotypes with direct relevance to human pathophysiological states. The ability to create gene ablations, gene duplications, and gene modifications should allow the use of genetic approaches to map in vivo pathways responsible for complex physiological phenotypes. Recent work from our laboratory utilizing this approach to study cardiac muscle diseases in both the adult context (cardiac hypertrophy) and in the embryonic context (congenital ventricular defects) will be discussed, as well as the steps that led to the generation and characterization of these novel mouse model systems. A large body of work from independent laboratories now points to the inception of a new field of molecular physiology that will fuse mouse genetics and in vivo physiology using appropriate miniaturized physiological technology. Recent advances and prospects for future directions are summarized.

scholarly journals Active contraction of cardiac muscle: In vivo characterization of mechanical activation sequences in the beating heart

2011 ◽  
Vol 4 (7) ◽  
pp. 1167-1176 ◽  
Author(s):  
Alkiviadis Tsamis ◽  
Wolfgang Bothe ◽  
John-Peder Escobar Kvitting ◽  
Julia C. Swanson ◽  
D. Craig Miller ◽  
...  
Keyword(s):  
Mechanical Activation ◽  
Cardiac Muscle ◽  
Beating Heart ◽  
Active Contraction ◽  
In Vivo Characterization

Selective chronic regulation of GLUT1 and GLUT4 content by insulin, glucose, and lipid in rat cardiac muscle in vivo

1997 ◽  
Vol 273 (3) ◽  
pp. H1309-H1316 ◽  
Author(s):  
D. R. Laybutt ◽  
A. L. Thompson ◽  
G. J. Cooney ◽  
E. W. Kraegen
Keyword(s):  
Cardiac Muscle ◽  
Plasma Glucose ◽  
Glucose Transporter ◽  
Close Association ◽  
Nonesterified Fatty Acid ◽  
Control Group ◽  
Dependent Manner ◽  
Energy Status ◽  
Glut1 Expression

The glucose transporter GLUT1 may play a more important role in cardiac than in skeletal muscle, but its regulation is unclear. During fasting, cardiac GLUT1 declines in the presence of low plasma insulin and glucose and high nonesterified fatty acid (NEFA) levels, whereas GLUT4 is unchanged. We investigated insulin, glucose, and NEFA levels as regulatory factors of cardiac GLUT content in chronically cannulated rats. Fasting rats were infused for 24 h with saline or insulin (2 rates) while plasma glucose was equalized by a glucose clamp; final transporter content was compared with a fed control group. There was a close association of GLUT1 content with insulin (r2 = 0.83, P < 0.001), with GLUT1 varying over a threefold range, under equivalent fasting glycemic conditions (plasma glucose, 5.1 +/- 0.1 mM). Maintenance of fed insulin levels during fasting prevented the GLUT1 fall (P < 0.01), whereas hyperinsulinemia (117 +/- 10 mU/l) led to significant overexpression of GLUT1 (155 +/- 12% of control, P < 0.01). When high glucose (7.6 +/- 0.1 mM) or high NEFA (0.76 +/- 0.05 mM) levels accompanied the hyperinsulinemia, upregulation of GLUT1 was blocked. GLUT1 content correlated with an estimate of cardiac glucose clearance across the groups. Cardiac GLUT4 content, hexokinase, and acyl-CoA synthase activities were unaffected by fasting, insulin, or substrate manipulation. In conclusion, insulin preferentially upregulates GLUT1 (but not GLUT4) in a dose-dependent manner in cardiac muscle in vivo, and substrate supply modulates this response, since upregulation can be effectively blocked by increased glucose or lipid availability. Therefore, both insulin exposure and energy status of cardiac muscle may be important determinants of cardiac GLUT1 expression.

scholarly journals Mechanisms for Intracellular Calcium Regulation in Heart

1973 ◽  
Vol 62 (6) ◽  
pp. 756-772 ◽  
Author(s):  
Antonio Scarpa ◽  
Pierpaolo Graziotti
Keyword(s):  
Cardiac Cells ◽  
Heart Mitochondria ◽  
Frog Heart ◽  
Cardiac Mitochondria ◽  
Physiological Regulation ◽  
Ca Transport ◽  
Ca Uptake ◽  
Intracellular Ca

Initial velocities of energy-dependent Ca++ uptake were measured by stopped-flow and dual-wavelength techniques in mitochondria isolated from hearts of rats, guinea pigs, squirrels, pigeons, and frogs. The rate of Ca++ uptake by rat heart mitochondria was 0.05 nmol/mg/s at 5 µM Ca++ and increased sigmoidally to 8 nmol/mg/s at 200 µM Ca++. A Hill plot of the data yields a straight line with slope n of 2, indicating a cooperativity for Ca++ transport in cardiac mitochondria. Comparable rates of Ca++ uptake and sigmoidal plots were obtained with mitochondria from other mammalian hearts. On the other hand, the rates of Ca++ uptake by frog heart mitochondria were higher at any Ca++ concentrations. The half-maximal rate of Ca++ transport was observed at 30, 60, 72, 87, 92 µM Ca++ for cardiac mitochondria from frog, squirrel, pigeon, guinea pig, and rat, respectively. The sigmoidicity and the high apparent Km render mitochondrial Ca++ uptake slow below 10 µM. At these concentrations the rate of Ca++ uptake by cardiac mitochondria in vitro and the amount of mitochondria present in the heart are not consistent with the amount of Ca++ to be sequestered in vivo during heart relaxation. Therefore, it appears that, at least in mammalian hearts, the energy-linked transport of Ca++ by mitochondria is inadequate for regulating the beat-to-beat Ca++ cycle. The results obtained and the proposed cooperativity for mitochondrial Ca++ uptake are discussed in terms of physiological regulation of intracellular Ca++ homeostasis in cardiac cells.

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