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Source: American Journal of Physiology. Heart and Circulatory Physiology

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Total 253 results found since Jan 2013.

Distinct hemodynamic responses to (Pyr)Apelin-13 in large animal models.
This study tested the hypothesis that (pyr)apelin-13 dose-dependently augments myocardial contractility and coronary blood flow, irrespective of changes in systemic hemodynamics. Acute effects of intravenous (pyr)apelin-13 administration (10 nM to 1,000 nM) on blood pressure, heart rate, left ventricular pressure and volume, and coronary parameters were measured in dogs and pigs. Administration of (pyr)apelin-13 did not influence blood pressure (P = 0.59), dP/dt-max (P = 0.26) or dP/dt-min (P = 0.85) in dogs. However, heart rate dose-dependently increased >70% (P < 0.01) which was accompanied by a significant increas...
Source: American Journal of Physiology. Heart and Circulatory Physiology - February 27, 2020 Category: Physiology Authors: Tune JD, Baker HE, Berwick ZC, Moberly S, Casalini ED, Noblet JN, Zhen E, Kowala MC, Christe ME, Goodwill AG Tags: Am J Physiol Heart Circ Physiol Source Type: research

Cerebrovascular carbon dioxide reactivity and flow mediated dilation in young healthy South Asian and Caucasian European men.
Abstract South Asians living in the UK have a 1.5-fold greater risk of ischemic stroke than the general population. Impaired cerebrovascular carbon dioxide (CO2) reactivity is an independent predictor of ischemic stroke and cardiovascular mortality. We sought to test the hypothesis that cerebrovascular CO2 reactivity is reduced in South Asians. Middle cerebral artery blood velocity (MCA Vm) was measured at rest and during stepwise changes in partial pressure of end-tidal CO2 (PETCO2) in South Asian (n=16) and Caucasian European (n=18) men that were, young (~20 years), healthy and living in the UK. Incremental hype...
Source: American Journal of Physiology. Heart and Circulatory Physiology - February 20, 2020 Category: Physiology Authors: Junejo RT, May S, Alsalahi S, Alali M, Ogoh S, Fisher JP Tags: Am J Physiol Heart Circ Physiol Source Type: research

Changes in left and right ventricular longitudinal function after pulmonary valve replacement in patients with Tetralogy of Fallot.
In conclusion, there is a clear atrioventricular coupling in patients before PVR that is lost after PVR, possibly due to loss of pericardial integrity. Impaired atrioventricular coupling complicates assessment of ventricular function after surgery using measurements of longitudinal function. Changes in atrioventricular coupling seen in patients with rToF may be energetically unfavourable and long-term effects of surgery on atrioventricular coupling is therefore of interest. Also, AVPD and GLS cannot be used interchangeably to assess longitudinal function in rToF. PMID: 31886724 [PubMed - as supplied by publisher]
Source: American Journal of Physiology. Heart and Circulatory Physiology - December 29, 2019 Category: Physiology Authors: Sjöberg P, Ostenfeld E, Hedström E, Arheden H, Gustafsson R, Nozohoor S, Carlsson M Tags: Am J Physiol Heart Circ Physiol Source Type: research

The Implementation of Physiological Afterload during Ex Situ Heart Perfusion Augments Prediction of Post-Transplant Function.
Abstract Ex Situ heart perfusion (ESHP) is an emerging technique that aims to increase the number of organs available for transplantation by augmenting both donor heart preservation and evaluation. Traditionally, ESHP has been performed in an unloaded Langendorff Mode (LM), though more recently groups have begun to use Pump Supported Working Mode (PSWM) and Passive Afterload Working Mode (PAWM) to enable contractile evaluation during ESHP. To this point, however, neither the predictive effectiveness of the two working modes, nor the predictive power of individual contractile parameters have been analyzed. In this ...
Source: American Journal of Physiology. Heart and Circulatory Physiology - November 26, 2019 Category: Physiology Authors: Gellner B, Xin L, Ribeiro RV, Bissoondath V, Adamson MB, Yu F, Lu P, Paradiso E, Mbadjeu A, Simmons CA, Badiwala MV Tags: Am J Physiol Heart Circ Physiol Source Type: research

ATP-dependent chromatin remodeling complexes in embryonic vascular development and hypertension.
Abstract Hypertension, a chronic elevation in blood pressure, is the largest single contributing factor to mortality worldwide and the most common preventable risk factor for cardiovascular disease. High blood pressure increases the risk for someone to experience a number of adverse cardiovascular events including heart failure, stroke, or aneurysm. Despite advancements in understanding factors that contribute to hypertension, the etiology remains elusive and there remains a critical need to develop innovative study approaches in order to develop more effective therapeutics. ATP-dependent chromatin remodelers are ...
Source: American Journal of Physiology. Heart and Circulatory Physiology - August 8, 2019 Category: Physiology Authors: Crosswhite PL Tags: Am J Physiol Heart Circ Physiol Source Type: research

Cardiac Troponin I Phosphorylation Underlies Myocardial Contractile Dysfunction Induced by Hypothermia-Rewarming.
Abstract Rewarming the intact heart after a period of hypothermia is associated with reduced myocardial contractility, decreased Ca2+ sensitivity and increased cardiac troponin I (cTnI) phosphorylation. We hypothesized that hypothermia/rewarming (H/R) induces left ventricular (LV) contractile dysfunction due to phosphorylation of cTnI at Ser 23/24. To test this hypothesis, the response of wildtype mice (n=7) to H/R was compared to transgenic mice expressing slow skeletal TnI (TG-ssTnI; n=7) that lacks the Ser 23/24 phosphorylation sites. Hypothermia was induced by surface cooling and maintained at 23-25ºC for 3 h...
Source: American Journal of Physiology. Heart and Circulatory Physiology - August 1, 2019 Category: Physiology Authors: Tveita T, Arteaga GM, Han YS, Sieck GC Tags: Am J Physiol Heart Circ Physiol Source Type: research

Upward resetting of the vascular sympathetic baroreflex in middle-aged male runners.
In conclusion, we suggest that neural remodelling and upward setting of the vascular sympathetic baroreflex compensates for cardiovascular adaptations after many years committed to endurance exercise training, presumably to maintain arterial blood pressure stability. PMID: 31050557 [PubMed - as supplied by publisher]
Source: American Journal of Physiology. Heart and Circulatory Physiology - May 2, 2019 Category: Physiology Authors: Wakeham DJ, Lord RN, Talbot JS, Lodge FM, Curry BA, Dawkins TG, Simpson LL, Shave RE, Pugh CJA, Moore JP Tags: Am J Physiol Heart Circ Physiol Source Type: research

Left Ventricular and Proximal Aorta Coupling in Magnetic Resonance Imaging: Aging Together?
CONCLUSIONS: Early age-related stiffening of the ascending aorta is a component of LV afterload subsequently associated with increased aortic impedance and alterations in LV geometry, namely concentric remodeling, decreased myocardial strain and increased stroke work such that LV wall stress and arterial-ventricular coupling are preserved. PMID: 30978118 [PubMed - as supplied by publisher]
Source: American Journal of Physiology. Heart and Circulatory Physiology - April 11, 2019 Category: Physiology Authors: Redheuil A, Kachenoura N, Bollache E, Yu WC, Opdahl A, De Cesare A, Mousseaux E, Bluemke D, Lima J Tags: Am J Physiol Heart Circ Physiol Source Type: research

Angiotensin Type 2 Receptor Stimulation With Compound 21 Improves Neurological Function after Stroke In Female Rats: A Pilot Study.
In conclusion, C21 improves stroke outcome in female rats probably through increased expression of PPARγ. The ability of C21 to exert its neuroprotective effects might be affected by fluctuating levels of female hormones. PMID: 30822121 [PubMed - as supplied by publisher]
Source: American Journal of Physiology. Heart and Circulatory Physiology - February 28, 2019 Category: Physiology Authors: Eldahshan W, Ishrat T, Pillai B, Sayed M, Alwhaibi A, Fouda AY, Ergul A, Fagan SC Tags: Am J Physiol Heart Circ Physiol Source Type: research

Beneficial Effects of Mesenchymal Stem Cell Delivery via a Novel Cardiac Bioscaffold on Right Ventricles of Pulmonary Arterial Hypertensive Rats.
In this study, we hypothesize that local mesenchymal stem cell (MSC) delivery via a novel bioscaffold can improve RV function despite persistent PAH. To test our hypothesis, we induced PAH in adult rats with SU5416 and chronic hypoxia exposure, treated with rat MSCs delivered by intravenous injection, intramyocardial injection or epicardial placement of a bioscaffold, and then examined treatment effectiveness by in vivo pressure-volume measurement, echocardiography, histology and immunohistochemistry. Our results showed that compared to other treatment groups, only the MSC-seeded bioscaffold group resulted in RV functional...
Source: American Journal of Physiology. Heart and Circulatory Physiology - February 28, 2019 Category: Physiology Authors: Schmuck EG, Hacker TA, Schreier DA, Chesler N, Wang Z Tags: Am J Physiol Heart Circ Physiol Source Type: research

Sex Differences in Cerebral Autoregulation is Unaffected by Menstrual Cycle Phase in Young, Healthy Women.
Abstract Sex is known to affect the prevalence of conditions such as stroke. However, effects of sex on cerebral blood flow regulation are still not well understood. Critical to this understanding is how fluctuations in hormones across the menstrual cycle affect cerebral autoregulation. We measured autoregulation in early follicular, late follicular, and mid-luteal phases during spontaneous and induced blood pressure oscillations in 26 (13 women) young (26 ± 4 years), healthy individuals. Men participated 3 times, ~1-3 weeks apart. Beat-by-beat blood pressure, heart rate, end-tidal CO2, and transcranial Doppler u...
Source: American Journal of Physiology. Heart and Circulatory Physiology - February 1, 2019 Category: Physiology Authors: Favre ME, Serrador JM Tags: Am J Physiol Heart Circ Physiol Source Type: research

Insights into the mechanism of paradoxical low-flow low-pressure-gradient severe aortic stenosis: association with reduced oxygen consumption by the whole body.
This study investigated the relationship between VO2, SVi and AS severity in patients with AS to examine the association between reduced VO2 and PLFLPG AS. In 59 patients (24 men, mean age 78±7 years) with severe AS, SVi, AS severity and type were evaluated by echocardiography, and VO2 was measured by the fraction of O2 in expired gases. The SVi and VO2 were significantly decreased in 20 patients with PLFLPG AS compared to those in 39 patients with non-PLFLPG AS (30±4 vs 41±7 ml/m2 and 2.4±0.5 vs 3.0±0.5 ml/min/kg, p < 0.01, respectively). The SVi to VO2 ratio was not different between the 2 groups (13.1±2.6 vs 13...
Source: American Journal of Physiology. Heart and Circulatory Physiology - January 25, 2019 Category: Physiology Authors: Onoue T, Iwataki M, Araki M, Itoh H, Isotani A, Umeda H, Fukuda S, Nagata Y, Tsuda Y, Fujino Y, Hanyu M, Ando K, Shirai S, Takeuchi M, Saeki S, Levine R, Otsuji Y Tags: Am J Physiol Heart Circ Physiol Source Type: research

Dynamic Cerebral Autoregulation Measurement using Rapid Changes in Head Positioning: Experiences in Acute Ischemic Stroke and Healthy Control Populations.
Abstract The ideal technique for dynamic cerebral autoregulation (dCA) assessment in critically ill patients should provide considerable variability in blood pressure (BP), but without the need for patient co-operation. We propose using rapid head positioning (RHP) over spontaneous BP fluctuations for dCA assessment in acute ischemic stroke (AIS) patients. Cerebral blood velocity (Transcranial Doppler), beat-to-beat BP (Finometer), and end-tidal carbon dioxide (ETCO2, capnography) were recorded during 5-min baseline and RHP in 16 controls (8 female, mean age 57 ± 16 years) and 15 AIS (7 female, mean age 69 ± 8 y...
Source: American Journal of Physiology. Heart and Circulatory Physiology - December 7, 2018 Category: Physiology Authors: Lam MY, Haunton VJ, Robinson TG, B Panerai R Tags: Am J Physiol Heart Circ Physiol Source Type: research

Effects of exercise training and TrkB blockade on cardiac function and BDNF-TrkB signaling post myocardial infarction in rats.
In conclusion, exercise-induced improvement of EF is mediated by the BDNF-TrkB axis and downstream effectors CaMKII and Akt. BDNF-TrkB signaling appears to contribute to the improvement in systolic function by exercise training. PMID: 30311496 [PubMed - as supplied by publisher]
Source: American Journal of Physiology. Heart and Circulatory Physiology - October 12, 2018 Category: Physiology Authors: Lee HW, Ahmad M, Weldrick JJ, Wang HW, Burgon PG, Leenen FHH Tags: Am J Physiol Heart Circ Physiol Source Type: research

Implications for understanding ischemic stroke as a sexually dimorphic disease: The role of pial collateral circulations.
Abstract We investigated structural and functional differences in primary and pial collateral circulations in adult normotensive male and female Wistar rats. Male (n=10) and female (n=7) rats were subjected to middle cerebral artery (MCA) occlusion and changes in relative cerebral blood flow (rCBF) in MCA and pial collateral territories were measured by multi-site laser Doppler flowmetry. Rats were then transcardially perfused with a mixture of carbon black and latex, perfusion fixed and imaged to compare primary and pial collateral structure between males (n=4) and females (n=3), including lumen diameters and num...
Source: American Journal of Physiology. Heart and Circulatory Physiology - September 21, 2018 Category: Physiology Authors: Li Z, Tremble SM, Cipolla MJ Tags: Am J Physiol Heart Circ Physiol Source Type: research