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Source: American Journal of Physiology. Heart and Circulatory Physiology

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Total 253 results found since Jan 2013.

The decrease of cardiac chamber volumes and output during positive pressure ventilation.
Conclusions Cardiac filling and output decrease with increasing PPV in healthy volun-teers. The decrease is seen even at low levels of PPV and should be taken into account when submitting patients to mechanical ventilation with positive pressures. The de-crease in CO is fully explained by the Frank-Starling mechanism. PMID: 23893161 [PubMed - as supplied by publisher]
Source: American Journal of Physiology. Heart and Circulatory Physiology - July 26, 2013 Category: Physiology Authors: Kristensen KK, Ahtarovski KA, Iversen KK, Thomsen C, Vejlstrup NG, Engstrøm T, Madsen PL Tags: Am J Physiol Heart Circ Physiol Source Type: research

Microneurographic evidence in healthy middle-aged humans for a sympathoexcitatory reflex activated by atrial pressure.
Abstract Atrial mechanoreceptors, stimulated by increased pressure or volume, elicit in healthy humans a net sympathoinhibitory response. The co-existence of an atrial reflex eliciting muscle sympathoexcitation has been postulated but undetected by conventional multi-unit muscle sympathetic nerve activity (MSNA). We hypothesized that in response to a selective increase in atrial pressure, single-unit MSNA would reveal a sub-population of efferent sympathetic neurons with firing patterns opposite to the integrated multi-unit MSNA envelope. Multi- and single-unit MSNA recordings were acquired in 8 healthy middle-age...
Source: American Journal of Physiology. Heart and Circulatory Physiology - July 12, 2013 Category: Physiology Authors: Millar PJ, Murai H, Morris BL, Floras JS Tags: Am J Physiol Heart Circ Physiol Source Type: research

A mathematical evaluation of hemodynamic parameters following carotid eversion and conventional patch angioplasty.
Conclusions: In a realistically simulated carotid artery, fluid-solid interaction modeling demonstrates CEE to produce less mechanical wall stress and improved flow patterns compared to CEAP. Clinical validation with larger numbers of individual patients will ultimately be required to support modeling approaches to help predict arterial disease progression and comparative effectiveness of reconstruction methods and devices. PMID: 23812386 [PubMed - as supplied by publisher]
Source: American Journal of Physiology. Heart and Circulatory Physiology - June 28, 2013 Category: Physiology Authors: Kamenskiy AV, Pipinos II, Dzenis YA, Gupta PK, Kazmi SA, Mactaggart JN Tags: Am J Physiol Heart Circ Physiol Source Type: research

Termination of Dobutamine Infusion Causes Transient Left Heart Diastolic Dysfunction in Healthy Elderly Women but Not in Men - A Magnetic Resonance Study.
Conclusions: Dobutamine causes greater stress to the female heart. This is revealed after termination of dobutamine stress where the left heart recovers in men whereas women experience rebound LV stiffening with reduced diastolic relaxation. This is the first report of gender-specific transient rebound phenomenon in cardiovascular response to catecholamines. PMID: 23812384 [PubMed - as supplied by publisher]
Source: American Journal of Physiology. Heart and Circulatory Physiology - June 28, 2013 Category: Physiology Authors: Ahtarovski KA, Iversen KK, Lønborg JT, Madsen PL, Engstrøm T, Vejlstrup NG Tags: Am J Physiol Heart Circ Physiol Source Type: research

Size-dependent predilections of cardiogenic embolic transport.
The objective of this study is to use medical imaging and computational modeling to better understand if aortic anatomy and embolus size influence predilections for cardiogenic embolic transport, and right versus left hemisphere propensity. Anatomically accurate models of the human aorta and branch arteries to the head were reconstructed from CT angiography of 10 patients. Blood flow was modeled by the Navier-Stokes equations using a well-validated flow solver with physiologic inflow and boundary conditions. Embolic particulate was released from the aortic root and tracked through the common carotid and vertebral arteries ...
Source: American Journal of Physiology. Heart and Circulatory Physiology - June 21, 2013 Category: Physiology Authors: Carr IA, Nemoto N, Schwartz RS, Shadden SC Tags: Am J Physiol Heart Circ Physiol Source Type: research

Strong linear relationship between heart rate and mean pulmonary artery pressure in exercising patients with severe precapillary pulmonary hypertension.
Abstract The contribution of heart rate (HR) to pulmonary artery hemodynamics has been suggested in pulmonary hypertension. Our high-fidelity pressure, retrospective study tested the hypothesis that HR explained the majority of mean pulmonary artery pressure (mPAP) and pulse pressure (PApp) variation in twelve severe precapillary pulmonary hypertension patients performing incremental-load cycling while supine. Seven idiopathic pulmonary arterial hypertension and five chronic thrombo-embolic pulmonary hypertension were studied. Four-to-five PAP-thermodilution cardiac output (CO) points (mean 4.4) were obtained. Hea...
Source: American Journal of Physiology. Heart and Circulatory Physiology - June 21, 2013 Category: Physiology Authors: Chemla D, Castelain V, Hoette S, Creuze N, Provencher S, Zhu K, Humbert M, Herve P Tags: Am J Physiol Heart Circ Physiol Source Type: research

Rat model of exercise-induced cardiac hypertrophy - hemodynamic characterization using left ventricular pressure-volume analysis.
Abstract Long-term exercise training is associated with characteristic structural and functional changes of the myocardium, termed athlete's heart. Several research groups investigated exercise training induced left ventricular (LV) hypertrophy in animal models, however only sporadic data exists about detailed hemodynamics. We aimed to provide functional characterization of exercise-induced cardiac hypertrophy in a rat model using the in vivo method of LV pressure-volume (P-V) analysis. After inducing LV hypertrophy by swim training, we assessed LV morphometry by echocardiography and performed LV P-V analysis usin...
Source: American Journal of Physiology. Heart and Circulatory Physiology - May 3, 2013 Category: Physiology Authors: Radovits T, Oláh A, Lux A, Németh BT, Hidi L, Birtalan E, Kellermayer D, Mátyás C, Szabó G, Merkely B Tags: Am J Physiol Heart Circ Physiol Source Type: research

The Effects of Hypertension on the Cerebral Circulation.
Abstract Maintenance of brain function depends on a constant blood supply. Deficits in cerebral blood flow are linked to cognitive decline, and they have detrimental effects on the outcome of ischemia. Hypertension causes alterations in cerebral artery structure and function that can impair blood flow particularly during an ischemic insult, or during periods of low arterial pressure. This review will focus on the historical discoveries, novel developments and knowledge gaps in: 1) hypertensive cerebral artery remodeling; 2) vascular function, with emphasis on myogenic reactivity and endothelium-dependent dilation;...
Source: American Journal of Physiology. Heart and Circulatory Physiology - April 12, 2013 Category: Physiology Authors: Pires PW, Dams Ramos CM, Matin N, Dorrance AM Tags: Am J Physiol Heart Circ Physiol Source Type: research

Inotropic and Lusitropic Effects of Calcitonin Gene-Related Peptide in the Heart.
Abstract Previous studies have demonstrated positive-inotropic effects of calcitonin gene-related peptide (CGRP) but the mechanisms remain unclear. Therefore, two experiments were performed to determine the physiological correlates of the positive-inotropic effects of CGRP. Treatments designed to antagonize the effects of physiologically-active CGRP 1-37 included post-treatment with CGRP8-37 and pretreatment with LY294002 (LY, an inhibitor of PI3K), 17β-estradiol (E) and progesterone (P) were also used to modulate the effects of CGRP1-37. Experiment 1: In vitro studies on sarcomeres and cells of isolated adult ra...
Source: American Journal of Physiology. Heart and Circulatory Physiology - April 12, 2013 Category: Physiology Authors: Al-Rubaiee M, Gangula PR, Millis RM, Walker RK, Umoh NA, Cousins VM, Jeffress MA, Haddad GE Tags: Am J Physiol Heart Circ Physiol Source Type: research

Impact of Tachycardia and Sympathetic Stimulation by Cold Pressor Test on Cardiac Diastology and Arterial Function in Elderly Females.
In conclusion, tachycardia and cold provocation in elderly females produces greater vascular reactivity and SV failure in the presence of arterial stiffening, but SV failure does not arise secondary to afterload-dependent attenuation of relaxation. PMID: 23355342 [PubMed - as supplied by publisher]
Source: American Journal of Physiology. Heart and Circulatory Physiology - January 25, 2013 Category: Physiology Authors: Johnson J, Håkansson F, Shahgaldi K, Manouras A, Norman M, Sahlén A Tags: Am J Physiol Heart Circ Physiol Source Type: research

Targets of Vascular Protection in Acute Ischemic Stroke Differ in Type 2 Diabetes.
The objective of the current study was to determine the effects of acute manipulation of potential targets for vascular protection (i.e., NFkB, peroxynitrite, and matrix metalloproteinases) on vascular injury and functional outcome in a diabetic model of cerebral ischemia. Ischemia was induced by middle cerebral artery occlusion in control and type 2 diabetic Goto-Kakizaki rats. Treatment groups received a single dose of peroxynitrite decomposition catalyst FeTPPs,a non-specific NFkB inhibitor curcumin, or a broad-spectrum matrix metalloproteinase (MMP) inhibitor minocycline at reperfusion. Post-stroke infarct volume, edem...
Source: American Journal of Physiology. Heart and Circulatory Physiology - January 18, 2013 Category: Physiology Authors: Kelly-Cobbs AI, Prakash R, Li W, Pillai B, Hafez S, Coucha M, Johnson MH, Ogbi SN, Fagan SC, Ergul A Tags: Am J Physiol Heart Circ Physiol Source Type: research

Kruppel-like Factor 2 Protects Against Ischemic Stroke by Regulating Endothelial Blood Brain Barrier Function.
In this study we sought to determine the role of KLF2 in cerebrovascular function and the pathogenesis of ischemic stroke. Transient middle cerebral artery occlusion (tMCAO) was performed in KLF2 deficient (KLF2(-/-)), KLF2 overexpressing (KLF2(tg)), and control mice and stroke volume analyzed. BBB function was assessed in vivo by real time neuroimaging using positron emission tomography (PET) and Evan's blue dye (EBD) assay. KLF2(-/-) mice exhibited significantly larger strokes and impairment in BBB function. In contrast, KLF2(tg) mice were protected against ischemic stroke and demonstrated preserved BBB function. In conc...
Source: American Journal of Physiology. Heart and Circulatory Physiology - January 18, 2013 Category: Physiology Authors: Shi H, Sheng B, Zhang F, Wu C, Zhang R, Zhu J, Xu K, Kuang Y, Jameson SC, Lin Z, Wang Y, Chen J, Jain MK, Atkins GB Tags: Am J Physiol Heart Circ Physiol Source Type: research

Heart rate changes mediate the embryotoxic effect of antiarrhythmic drugs in the chick embryo.
Abstract A significant increase in cardiovascular medication use during pregnancy occurred in recent years. Only limited evidence on safety profiles is available and little is known about the mechanisms of adverse effect on the fetus. We hypothesized that drug-induced bradycardia is the leading mechanism of developmental toxicity. Embryotoxicity was tested in ovo after administration of various doses of metoprolol, carvedilol, or ivabradine. Embryonic day (ED) 4 and 8 chick embryos were studied by video microscopy and ultrasound biomicroscopy ex ovo after intraamniotic injection of the drug for a period of 30 minu...
Source: American Journal of Physiology. Heart and Circulatory Physiology - January 11, 2013 Category: Physiology Authors: Kockova R, Svatunkova J, Novotny J, Hejnova L, Ostadal B, Sedmera D Tags: Am J Physiol Heart Circ Physiol Source Type: research