Influence of exercise on excitation-contraction coupling in rat myocardium

1981 ◽  
Vol 240 (4) ◽  
pp. H472-H480 ◽  
Author(s):  
G. F. Tibbits ◽  
R. J. Barnard ◽  
K. M. Baldwin ◽  
N. Cugalj ◽  
N. K. Roberts
Keyword(s):  
Binding Sites ◽  
Action Potentials ◽  
Left Ventricular ◽  
Female Rats ◽  
Contractile Element ◽  
Resting Membrane Potential ◽  
Control Group ◽  
Cross Sectional ◽  
Significant Prolongation ◽  
Isometric Twitch

The present studies were conducted to investigate further the mechanisms by which the myocardium adapts to exercise training. Sixty female rats were randomly divided into sedentary control (group C) and trained (group T) groups. Group T was progressively trained for 12 wk. After the rats were killed, left ventricular papillary muscles were mounted in a tissue bath for mechanical studies. Muscles from group T generated greater peak isometric twitch tension per unit cross-sectional area than muscles from group C with [Ca2+]o ranging from 0.25 to 3.5 mM. Analyses of these data indicated that the Km for Ca2+ was not different but that the predicted number of sarcolemmal Ca2+ binding sites was 63% higher in group T. The ATPase activity of the purified cardiac myofibrils was not different between the two groups in the pCa range of 8.53-4.42. Action potentials were recorded with microelectrodes impaled into left ventricular muscle fibers of the subendocardium. Although there was no difference in the resting membrane potential, overshoot, or 90% duration, there was a significant prolongation of the action potential at 0 mV (20.2 +/- 1.0 vs 30.0 +/- 1.3 ms) in group T. These data further support the hypothesis that treadmill exercise enhances cardiac performance by increasing Ca2+ availability to the contractile element. This adaptation is mediated, at least in part, by a sarcolemmal adaptation induced by the exercise paradigm.

Cardiac vasculature and flow during pressure-overload hypertrophy

1986 ◽  
Vol 251 (5) ◽  
pp. H1031-H1037 ◽  
Author(s):  
E. A. Breisch ◽  
F. C. White ◽  
L. E. Nimmo ◽  
C. M. Bloor
Keyword(s):  
Blood Flow ◽  
Myocardial Blood Flow ◽  
Weight Ratio ◽  
Pressure Overload ◽  
Capillary Density ◽  
Left Ventricular ◽  
Control Group ◽  
Cross Sectional ◽  
Ventricle Hypertrophy ◽  
Aortic Cuff

The effects of pressure-overload hypertrophy (H) on myocardial blood flow and microvasculature were studied in the porcine left ventricle. Hypertrophy was produced in nine adult pigs by an aortic cuff constriction of the ascending aorta. Eight pigs served as controls. After 30 days the aortic cuff was released, and the hypertrophy group was studied 1 day postrelease. The degree of hypertrophy, determined by left ventricular-to-body weight ratio, was 45%. With hypertrophy, left ventricular blood flows were normal at rest. During exercise with adenosine infusion, myocardial blood flow to the endomyocardium was reduced compared with the control (C) group (H = 4.02 +/- 0.35, P less than 0.05; C = 5.33 +/- 0.41 ml X min-1 X g-1). Minimal coronary vascular resistance in the endomyocardium was increased during exercise with adenosine in the hypertrophy group compared with the control group. Anatomic studies revealed that hypertrophy causes a reduction in the endomyocardial capillary density (H = 1,654 +/- 168, P less than 0.025; C = 2,168 +/- 106, no./mm2) with a similar trend noted for the transmural arteriolar density. Arteriolar media wall cross-sectional area was unaffected by the pressure overload. These results indicate that changes in the vascular bed do not parallel myocyte growth during pressure-overload hypertrophy. The resultant anatomic imbalance compromises endomyocardial flow, making this region vulnerable to ischemia.

scholarly journals Relationship between obesity and left ventricular hypertrophy in children

2016 ◽  
Vol 50 (6) ◽  
pp. 331
Author(s):  
Johnny Rompis ◽  
Erling David Kaunang
Keyword(s):  
Left Ventricular Hypertrophy ◽  
Ventricular Hypertrophy ◽  
Cross Sectional Study ◽  
Left Ventricular ◽  
Control Group ◽  
Obese Children ◽  
Cross Sectional ◽  
Diastolic Compliance ◽  
And Function ◽  
And Control

Background Obesity is a chronic metabolic disorder associated with cardiovascular disease (CVD) increasing morbidity-mortality rates. It is apparent that a variety of adaptations/alterations in cardiac structure and function occurs as excessive adipose tissue accumulates. This leads to a decrease in diastolic compliance, eventually resulting in an increase in left ventricular filling pressure and left ventricular enlargement.Objective To evaluate left ventricular hypertrophy (LVH) among  obese using electrocardiographic (ECG) criteria.Methods A cross-sectional study was conducted on 74 children aged 10-15 years from February 2009 to October 2009. The subjects were divided into obese and control groups. Physical examination and standard 12 lead electrocardiography (ECG) were done in both groups.Results Of 37 obese children, LVH were featured in 3 subjects, while in control group, only 1 child had LVH (P= 0.304). We found that mean RV6 in obese and control group were 9.8446 (SD 3.5854) and 11.9662 (SD 3.2857), respectively (P=0.005). As an additional findings, we found that birth weight was related to obesity in children.Conclusion There is no relation between obesity and left ventricular using ECG criteria in obese children aged 10-15 years.

scholarly journals Myonecrosis in Aortic Valvular Heart Diseases

2009 ◽  
Vol 13 (Number 2) ◽  
pp. 9-12
Author(s):  
Md. Khalequzzaman ◽  
M A Islam ◽  
Md. O Hoque ◽  
M Ferdous ◽  
A H K Chowdhury ◽  
...  
Keyword(s):  
Aortic Stenosis ◽  
Heart Diseases ◽  
Cross Sectional Study ◽  
Left Ventricular ◽  
Definitive Treatment ◽  
Control Group ◽  
Cross Sectional ◽  
Valvular Heart Diseases ◽  
Significant Difference ◽  
Venous Sample

This cross sectional study was done among 20 patients with aortic stenosis and 20 healthy controls to evaluate the association of cardiac specific troponin 1 (ant) and sonic valvular heart diseases. The study was conducted in °militant, department in National laminae of Cardiovascular Diseases (N1CVD.)A structured queslionilaire and checklist was used to collect data through face to face interview. Color dapple, echocarchiognsphy was done and 5 ml of venous sample was dmwo from each subjects and laboratory estimation of an, was done. The arid in control group and sonic stenosis patients showed significant difference in mean (<0.001). ant level in aortic stenosis patients increases in the absence of heart failure indicating that it can expose the cardiotnyocnes to injury prior to development of oven left ventricular dysftinction. So. serial monitoring of aid may help clinicians to give definitive treatment (reface development af complications.

scholarly journals Plasma Brain Natriuretic Peptide (BNP) as an Indicator of Left Ventricular Function, Early Outcome and Mechanical Complications after Acute Myocardial Infarction

2011 ◽  
Vol 5 ◽  
pp. CMC.S7189 ◽  
Author(s):  
A. Fazlinezhad ◽  
M. Khadem Rezaeian ◽  
H. Yousefzadeh ◽  
K. Ghaffarzadegan ◽  
M. Khajedaluee
Keyword(s):  
Myocardial Infarction ◽  
Acute Myocardial Infarction ◽  
Left Ventricular Function ◽  
Ventricular Function ◽  
Natriuretic Peptide ◽  
Significant Relationship ◽  
Left Ventricular ◽  
Control Group ◽  
Cross Sectional ◽  
Mechanical Complications

Aims This study investigated the prognostic value of B type natriuretic peptide (BNP) in acute myocardial infarction (AMI) patients and its relation with left ventricular function and post-myocardial infarction complications. Methods In this cross-sectional study, plasma BNP level was measured for 42 consecutive patients (mean ± SD: 61.6 ± 10.85 years old) with acute ST elevation myocardial infarction (MI) and 42 healthy, age and gender matched subjects. Result BNP level in AMI patients were significantly higher than control group (@ P < 0.001). Regarding to infarct location, the highest BNP level measured in inferoposterior MI (BNP = 4436.63 ± 6188.159 pg/ml) and the lowest one indicated in standalone inferior MI (BNP = 598.83 ± 309.867 pg/ml ( P = 0.071). There was significant reverse relation between BNP and EF ( P = 0.006, OR = −0.47) and a significant relationship between BNP and killip classification ( P = 0.036). There was no significant relation between diastolic and right-ventricular function and BNP level ( P = 0.61, P = 0.21). The highest BNP level was detected in LV septal rupture and false aneurysm ( P = 0.02) and in ventricular tachycardia, but without significant relationship ( P = 0.25). Conclusion After the onset of AMI, BNP blood level can be used as an important predictor for left ventricular dysfunction, killip classification, early mechanical complications and cardiac death.

Studying of morphology and left ventricular function by conventional and speckle tracking echocardiography in football players

2019 ◽  
pp. 36-40
Author(s):  
Kien Duoc Vang ◽  
Anh Vu Nguyen
Keyword(s):  
Tissue Doppler Imaging ◽  
Speckle Tracking ◽  
Circumferential Strain ◽  
Speckle Tracking Echocardiography ◽  
Early Stage ◽  
Tissue Doppler ◽  
Left Ventricular ◽  
Doppler Imaging ◽  
Control Group ◽  
Cross Sectional

Objective: Recent studies have showed that Tissue Doppler Imaging and Speckle Tracking Echocardiography can discover these changes at functional and structural cardiac in athletes at early stage, especially at the footballers. The purpose of this research was evaluated the structural and functional adaption of left ventricular in footballer by conventional and advanced echocardiography. Materials and methods: We performed a cross-sectional study of 30 footballers who have been trained over 2 years compared to 30 healthy candidate with the same ages. We carried out TM, 2D, STE. Echo machine was Philips Affinity 50CV with QLAB version 10.04 which can analyze online or offline. Result: In comparison with control group, IVSd, LVEDd, PWTd, LVM, LVMI (p = 0.001) was different from athlete group. Left ventricular adaption trended to eccentric hypertrophy and increased left ventricular mass index. A wave was decrease velocity and increased E/A, E/El’, E/E’s ratio. Base circumferential strain, apex circumferential strain, rotation and twist (10.12 ± 1.2) (°) athletes (7.42 ± 2.6) (°) control group with (p = 0.05), were more than control group. Conclusion: Conventional and advanced echocardiography can evaluate structural and functional left ventricular adaption in athletes. Especially, STE provided more data in myocardial deformation, rotation and twist so that it can discover these changes at athlete heart in early stages Key words: Athletes heart, Speckle Tracking Echocardiography, Tissue Doppler Imaging

Study of Systolic and Diastolic Dysfunction among Normotensive Patients with Type 2 Diabetes Mellitus – A Cross–Sectional Study from Puducherry, India

2021 ◽  
Vol 8 (37) ◽  
pp. 3344-3349
Author(s):  
Suman Babu I.S.S. ◽  
Sethu Prabhu Shankar ◽  
Harshavardhan Reddy ◽  
Surya Usha Surendran Nair
Keyword(s):  
Diabetes Mellitus ◽  
Risk Factors ◽  
Cardiovascular Disease ◽  
Diastolic Dysfunction ◽  
Systolic Dysfunction ◽  
Left Ventricular ◽  
Control Group ◽  
Diabetic Patients ◽  
Cross Sectional ◽  
A Value

BACKGROUND Diabetes mellitus (DM) single-handedly accounts for 75 – 90 % of excess coronary artery disease (CAD) risk seen in persons suffering from it and it also enhances and amplifies the effects of other traditional cardiovascular risk factors. After adjusting for concomitant risk factors such as hypertension and hyperlipidemia, there still remains an excess risk for cardiovascular disease (CVD) in people with diabetics. In this study, we wanted to evaluate left ventricular (LV) systolic and diastolic dysfunction in normotensive diabetic patients. METHODS A cross sectional comparative study was performed from January 2016 to September 2017 on 50 diabetics and 50 age and sex matched healthy controls. Adult patients of both sexes with diabetes mellitus who are normotensive were included as cases. Patients with known heart disease, chronic kidney disease, thyroid disorders were excluded from the study. 2D transthoracic echocardiogram (ECHO) with M mode was used for assessing systolic and diastolic function. RESULTS Mean ejection fraction was lower in patients group (59.76) as compared to control group (64.74) with 8 % of cases with a value of< 50 %. Fractional shortening was also lower in patients (29.14) compared to controls (34.86) with 12 % patients having a value of < 25 %. E/A ratio was 1.12 in patients when compared to 1.36 in controls with 32 % of patients having value < 1. Mean isovolumic relaxation time was 96.52 in patients when compared to 87.42 in controls with 24 % patients having value > 100 msec. CONCLUSIONS Normotensive diabetics are prone to left ventricular dysfunction. Diastolic dysfunction is more common than systolic dysfunction. KEYWORDS Diabetes Mellitus, Systolic Dysfunction, Diastolic Dysfunction, Cardiovascular Disease

Altered spatial calcium regulation enhances electrical heterogeneity in the failing canine left ventricle: implications for electrical instability

2012 ◽  
Vol 112 (6) ◽  
pp. 944-955 ◽  
Author(s):  
Vivek Iyer ◽  
Victoria Heller ◽  
Antonis A. Armoundas
Keyword(s):  
Heart Failure ◽  
Action Potentials ◽  
Left Ventricular ◽  
Simulation Studies ◽  
Electrophysiological Properties ◽  
Failing Heart ◽  
Cellular Electrophysiology ◽  
Electrical Instability ◽  
Significant Prolongation ◽  
Intracellular Ca

Myocytes across the left ventricular (LV) wall of the mammalian heart are known to exhibit heterogeneity of electrophysiological properties; however, the transmural variation of cellular electrophysiology and Ca2+ homeostasis in the failing LV is incompletely understood. We studied action potentials (APs), the L-type calcium (Ca2+) current ( ICa,L), and intracellular Ca2+ transients ([Ca2+]i) of subendocardial (Endo), midmyocardial (Mid), and subepicardial (Epi) tissue layers in the canine normal and tachycardia pacing-induced failing left ventricles. Heart failure (HF) was associated with significant prolongation of the AP duration in Mid myocytes. There were no differences in ICa,L density in normal Endo, Mid, and Epi myocytes, whereas in the failing heart, ICa,L density was downregulated by 45% and 26% (at +10 mV) in Endo and Mid myocytes, respectively. The rates of sarcoplasmic reticulum (SR) Ca2+ release and decay of the [Ca2+]i were slowed, and the amplitude of the [Ca2+]i was depressed in Endo and Epi myocytes isolated from failing, compared with normal, hearts. Experiments in sodium (Na+)-free solutions showed that Epi and Mid myocytes of the failing ventricle exhibit a greater reliance on the Na+-Ca2+ exchanger to remove cytosolic Ca2+ than myocytes isolated from normal hearts. Simulation studies in Endo, Mid, and Epi canine myocytes demonstrate the importance of L-type current density and SR Ca2+ uptake in modulating the potentially arrhythmogenic repolarization in HF. In conclusion, these results demonstrate that spatially heterogeneous decreases in ICa,L and defective cytosolic Ca2+ removal contribute to the altered [Ca2+]i and AP profiles across the canine failing LV. These distinct electrophysiological features in myocytes from a failing heart contribute to a characteristic electrogram arising from increased dispersion of refractoriness across the LV, which may result in significant arrhythmogenic sequellae.

scholarly journals Ventricular remodeling induced by retinoic acid supplementation in adult rats

2003 ◽  
Vol 284 (6) ◽  
pp. H2242-H2246 ◽  
Author(s):  
Sergio Alberto Rupp de Paiva ◽  
Leonardo Antonio Mamede Zornoff ◽  
Marina Politi Okoshi ◽  
Katashi Okoshi ◽  
Luiz Shiguero Matsubara ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Papillary Muscle ◽  
Ventricular Remodeling ◽  
Volume Fraction ◽  
Maximum Velocity ◽  
Left Ventricular ◽  
Control Group ◽  
Adult Rats ◽  
Cross Sectional ◽  
Morphological Studies

Retinoic acid (RA) plays a role in regulating cardiac geometry and function throughout life. The aim of this study was to analyze the cardiac effects of RA in adult rats. Wistar rats were randomly allocated to a control group ( n = 18) receiving standard rat chow and a group treated with RA ( n = 14) receiving standard rat chow supplemented with RA for 90 days. All animals were evaluated by echocardiography, isolated papillary muscle function, and morphological studies. Whereas the RA-treated group developed an increase in both left ventricular (LV) mass and LV end-diastolic diameter, the ratio of LV wall thickness to LV end-diastolic diameter remained unchanged when compared with the control group. In the isolated papillary muscle preparation, RA treatment decreased the time to peak developed tension and increased the maximum velocity of isometric relengthening, indicating that systolic and diastolic function was improved. Although RA treatment produced an increase in myocyte cross-sectional area, the myocardial collagen volume fraction was similar to controls. Thus our study demonstrates that small physiological doses of RA induce ventricular remodeling resembling compensated volume-overload hypertrophy in rats.

Wine polyphenols improve cardiovascular remodeling and vascular function in NO-deficient hypertension

2002 ◽  
Vol 282 (3) ◽  
pp. H942-H948 ◽  
Author(s):  
Iveta Bernátová ◽  
Olga Pechánová ◽  
Pavel Babál ◽  
Sona Kyselá ◽  
Svetoslav Stvrtina ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Myocardial Fibrosis ◽  
Vascular Function ◽  
Spontaneous Recovery ◽  
Left Ventricular ◽  
No Synthase ◽  
Control Group ◽  
Cross Sectional ◽  
Wine Polyphenols ◽  
Group A

The effects of the red wine polyphenolic compounds (Provinol) on hypertension, left ventricular hypertrophy, myocardial fibrosis, and vascular remodeling were investigated after chronic inhibition of nitric oxide (NO) synthase by administration of N G-nitro-l-arginine methyl ester (l-NAME) to rats. Rats were divided into four groups: a control group, a group treated for 4 wk with l-NAME (40 mg · kg−1 · day−1), and two groups treated with l-NAME followed by 3 wk of either spontaneous recovery or recovery with Provinol treatment (40 mg · kg−1 · day−1). Administration of Provinol produced a greater readiness of the decrease in blood pressure than that in the spontaneous recovery group. Provinol significantly depressed myocardial fibrosis and expedited the decrease in aortic cross-sectional area, the increase in endothelium-dependent relaxation, and the decrease in contraction of the aorta. These effects of Provinol were associated with a greater increase of NO synthase activity in the left ventricle and the aorta. The present study provides evidence that Provinol accelerates the regression of blood pressure and improves structural and functional cardiovascular changes produced by chronic inhibition of NO synthesis.

Load-sensitive diastolic relaxation in hypertrophied left ventricles

1998 ◽  
Vol 274 (2) ◽  
pp. H609-H615 ◽  
Author(s):  
Wataru Hayashida ◽  
Julian Donckier ◽  
Henri Van Mechelen ◽  
André A. Charlier ◽  
Hubert Pouleur
Keyword(s):  
Relaxation Time ◽  
Angiotensin Ii ◽  
Time Constant ◽  
Left Ventricular ◽  
Control Group ◽  
Relaxation Time Constant ◽  
Significant Prolongation ◽  
Wide Range ◽  
Diastolic Relaxation

We studied effects of enalaprilat and L-158,809, an angiotensin II type-1 receptor antagonist, on left ventricular (LV) diastolic relaxation in 11 normal control dogs and 16 LV hypertrophied (LVH) dogs with perinephritic hypertension. At baseline, LV systolic and end-diastolic pressures and end-systolic elastance were increased in the LVH group (all P < 0.01 vs. the control group). LV relaxation time constant was also prolonged ( P < 0.01), suggesting impaired LV diastolic relaxation in this model of LVH. Before and after the administration of enalaprilat (0.25 mg/kg) and L-158,809 (0.30 mg/kg), LV relaxation was assessed over a wide range of LV loading conditions during vena caval occlusion. LV relaxation time constant was insensitive to load reduction in the control group, which was not affected by enalaprilat or L-158,809. In contrast, LV unloading caused a significant prolongation of the relaxation time constant in the LVH group. This load-sensitive LV relaxation abnormality was significantly improved by enalaprilat or L-158,809. These results support the concept that angiotensin II is involved in the pathogenesis of diastolic dysfunction in pressure-overloaded LVH and also suggest that angiotensin-converting enzyme inhibitors and angiotensin II type-1 receptor antagonists are potentially beneficial in the treatment of the hypertrophied heart.

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