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The normal ranges of cardiovascular parameters measured using the ultrasonic cardiac output monitor
This study aimed to (1) measure cardiovascular indices using USCOM in healthy adults aged 18–60 years; (2) combine these data with those for healthy children (aged 0–12), adolescents (aged 12–18), and the elderly (aged over 60) from our previously published studies in order to present normal ranges for all ages, and (3) establish normal ranges of USCOM‐derived variables according to both weight and age. This was a population‐based cross‐sectional observational study of healthy Chinese subjects aged 0.5–89 years in Hong Kong. USCOM scans were performed on all subjects, to produce measurements including strok...
Source: Physiological Reports - March 20, 2017 Category: Physiology Authors: Giles N. Cattermole, P. Y. Mia Leung, Grace Y. L. Ho, Peach W. S. Lau, Cangel P. Y. Chan, Stewart S. W. Chan, Brendan E. Smith, Colin A. Graham, Timothy H. Rainer Tags: Original Research Source Type: research

Acute effects of glucagon ‐like peptide‐1, GLP‐19–36 amide, and exenatide on mesenteric blood flow, cardiovascular parameters, and biomarkers in healthy volunteers
Abstract Glucagon‐like peptide‐1 (GLP‐1, GLP‐17–36amide) and its sister peptide glucagon‐like peptide 2 (GLP‐2) influence numerous intestinal functions and GLP‐2 greatly increases intestinal blood flow. We hypothesized that GLP‐1 also stimulates intestinal blood flow and that this would impact on the overall digestive and cardiovascular effects of the hormone. To investigate the influence of GLP‐1 receptor agonism on mesenteric and renal blood flow and cardiovascular parameters, we carried out a double‐blinded randomized clinical trial. A total of eight healthy volunteers received high physiological s...
Source: Physiological Reports - February 23, 2017 Category: Physiology Authors: Lasse Bremholm, Ulrik B. Andersen, Mads Hornum, Linda Hilsted, Simon Veedfald, Bolette Hartmann, Jens Juul Holst Tags: Original Research Source Type: research

Hemodynamic responses are reduced with aerobic compared with resistance blood flow restriction exercise
In conclusion, the hemodynamic response for light aerobic (walking) BFR exercise suggests this mode of BFR exercise may be preferential for chronic use to develop muscle size and strength, and other health benefits in certain clinical populations that are contraindicated to heavy‐load resistance exercise. The present study demonstrated that hemodynamic measures with blood‐flow restriction (BFR) resistance exercise are similar to HLRE but greater than aerobic BFR walking exercise, which are similar to non‐BFR control walking exercise. In addition, lower rating of perceived exertion (RPE) scores were observed for aero...
Source: Physiological Reports - February 8, 2017 Category: Physiology Authors: Anthony K. May, Christopher R. Brandner, Stuart A. Warmington Tags: Original Research Source Type: research

Increased cardiac work provides a link between systemic hypertension and heart failure
Abstract The spontaneously hypertensive rat (SHR) is an established model of human hypertensive heart disease transitioning into heart failure. The study of the progression to heart failure in these animals has been limited by the lack of longitudinal data. We used MRI to quantify left ventricular mass, volume, and cardiac work in SHRs at age 3 to 21 month and compared these indices to data from Wistar‐Kyoto (WKY) controls. SHR had lower ejection fraction compared with WKY at all ages, but there was no difference in cardiac output at any age. At 21 month the SHR had significantly elevated stroke work (51 ± 3 mL.mmHg...
Source: Physiological Reports - January 12, 2017 Category: Physiology Authors: Alexander J. Wilson, Vicky Y. Wang, Gregory B. Sands, Alistair A. Young, Martyn P. Nash, Ian J. LeGrice Tags: Original Research Source Type: research

Breathing 100% oxygen during water immersion improves postimmersion cardiovascular responses to orthostatic stress
This study was conducted to compare hemodynamic responses to postural stress following exposure to WI alone (Air WI), hyperbaric oxygen alone in a hyperbaric chamber (O2 HC), and WI combined with hyperbaric oxygen (O2 WI), all at a depth of 1.35 ATA, and to determine whether hyperbaric oxygen is protective of orthostatic tolerance. Thirty‐two healthy men underwent up to 15 min of 70° head‐up tilt (HUT) testing before and after a single 6‐h resting exposure to Air WI (N = 10), O2 HC (N = 12), or O2 WI (N = 10). Heart rate (HR), blood pressure (BP), cardiac output (Q), stroke volume (SV), forearm blood flow (FB...
Source: Physiological Reports - December 15, 2016 Category: Physiology Authors: John P. Florian, Ki H. Chon, Luca Faes, Barbara E. Shykoff Tags: Original Research Source Type: research

Cardiac responses to exercise distinguish postural orthostatic tachycardia syndrome variants
In conclusion, we identified a variant of POTS with a hypokinetic circulation maintained by a vasoconstricted state. We speculate that they cannot muster preload to augment exercise SV due to profound thoracic hypovolemia, and must resort to vasoconstriction in order to maintain perfusion pressure within working muscle. Alterations in resting limb blood flow have been documented in patients with postural orthostatic tachycardia syndrome. We have not extended this model to exercise, showing there are three subgroups within this heterogeneous population. The unifying underlying pathophysiology is likely dysregulation of aut...
Source: Physiological Reports - November 23, 2016 Category: Physiology Authors: Paolo T. Pianosi, Darrell R. Schroeder, Philip R. Fischer Tags: Original Research Source Type: research

In vivo assessment of coronary flow and cardiac function after bolus adenosine injection in adenosine receptor knockout mice
In this study, we used ultrasound imaging to measure the in vivo effects of adenosine on coronary blood flow (left coronary artery) and cardiac function in anesthetized wild‐type, A1 knockout (KO), A2AKO, A2BKO, A3KO, A1, and A3 double KO (A1/3 DKO) and A2A and A2B double KO (A2A/2B DKO) mice in real time. Echocardiographic and Doppler studies were performed using a Visualsonic Vevo 2100 ultrasound system. Coronary blood flow (CBF) baseline data were obtained when animals were anesthetized with 1% isoflourane. Diameter (D) and velocity time integral (VTI) were measured on the left coronary arteries (CBF = ((π/4) ×�...
Source: Physiological Reports - June 13, 2016 Category: Physiology Authors: Bunyen Teng, Stephen L. Tilley, Catherine Ledent, S. Jamal Mustafa Tags: Original Research Source Type: research

Cardiometabolic risk factors predict cerebrovascular health in older adults: results from the Brain in Motion study
Abstract Aging and physical inactivity are associated with an increased risk of developing metabolic syndrome (MetS). With the rising prevalence of MetS, it is important to determine the extent to which it affects cerebrovascular health. The primary purpose of this report is to examine the impact of MetS on cerebrovascular health (resting cerebral blood flow (CBF) peak velocity (), cerebrovascular conductance (CVC), and CBF responses to hypercapnia) in healthy older adults with normal cognition. A secondary goal was to examine the influence of apolipoprotein E (APOE) ε4 expression on these indices. In a sample of 258 heal...
Source: Physiological Reports - April 24, 2016 Category: Physiology Authors: Amanda V. Tyndall, Laurie Argourd, Tolulope T. Sajobi, Margie H. Davenport, Scott C. Forbes, Stephanie J. Gill, Jillian S. Parboosingh, Todd J. Anderson, Ben J. Wilson, Eric E. Smith, David B. Hogan, Michael D. Hill, Marc J. Poulin Tags: Original Research Source Type: research

Variability in integration of mechanisms associated with high tolerance to progressive reductions in central blood volume: the compensatory reserve
Abstract High tolerance to progressive reductions in central blood volume has been associated with higher heart rate (HR), peripheral vascular resistance (PVR), sympathetic nerve activity (SNA), and vagally mediated cardiac baroreflex sensitivity (BRS). Using a database of 116 subjects classified as high tolerance to presyncopal‐limited lower body negative pressure (LBNP), we tested the hypothesis that subjects with greater cardiac baroreflex withdrawal (i.e., BRS > 1.0) would demonstrate greater LBNP tolerance associated with higher HR, PVR, and SNA. Subjects underwent LBNP to presyncope. Mean and diastolic arteria...
Source: Physiological Reports - February 16, 2016 Category: Physiology Authors: Robert Carter, Carmen Hinojosa‐Laborde, Victor A. Convertino Tags: Original Research Source Type: research

Changes in corticospinal drive to spinal motoneurones following tablet‐based practice of manual dexterity
Abstract The use of touch screens, which require a high level of manual dexterity, has exploded since the development of smartphone and tablet technology. Manual dexterity relies on effective corticospinal control of finger muscles, and we therefore hypothesized that corticospinal drive to finger muscles can be optimized by tablet‐based motor practice. To investigate this, sixteen able‐bodied females practiced a tablet‐based game (3 × 10 min) with their nondominant hand requiring incrementally fast and precise pinching movements involving the thumb and index fingers. The study was designed as a semirandomized cro...
Source: Physiological Reports - January 26, 2016 Category: Physiology Authors: Lisbeth H. Larsen, Thor Jensen, Mark S. Christensen, Jesper Lundbye‐Jensen, Henning Langberg, Jens B. Nielsen Tags: Original Research Source Type: research

Motor planning poststroke: impairment in vector‐coded reach plans
We examined whether these vector and target reach‐planning codes are differentially affected after stroke. Participants with stroke and healthy controls made blocks of reaches that were grouped by target location (providing target‐specific practice) and by movement vector (providing vector‐specific practice). Reach accuracy was impaired in the more affected arm after stroke, but not distinguishable for target‐ versus vector‐grouped reaches. Reach velocity and acceleration were not only impaired in both the less and more affected arms poststroke, but also not distinguishable for target‐ versus vector‐grouped r...
Source: Physiological Reports - December 10, 2015 Category: Physiology Authors: John‐Ross Rizzo, Todd E. Hudson, Andrew Abdou, Ira G. Rashbaum, Ajax E. George, Preeti Raghavan, Michael S. Landy Tags: Original Research Source Type: research

Reproducibility of a continuous ramp lower body negative pressure protocol for simulating hemorrhage
Abstract Central hypovolemia elicited by application of lower body negative pressure (LBNP) has been used extensively to simulate hemorrhage in human subjects. Traditional LBNP protocols incorporate progressive steps in pressure held for specific time intervals. The aim of this study was to assess the reproducibility of applying continuous LBNP at a constant rate until presyncope to replicate actual bleeding. During two trials (≥4 weeks intervening), LBNP was applied at a rate of 3 mmHg/min in 18 healthy human subjects (12M; 6F) until the onset of presyncopal symptoms. Heart rate (HR), mean arterial pressure (MAP), str...
Source: Physiological Reports - November 25, 2015 Category: Physiology Authors: Victoria L. Kay, Caroline A. Rickards Tags: Original Research Source Type: research

Hemodynamic variability and cerebrovascular control after transient cerebral ischemia
Abstract We investigated if hemodynamic variability, cerebral blood flow (CBF) regulation, and their interrelationships differ between patients with transient ischemic attack (TIA) and controls. We recorded blood pressure (BP) and bilateral middle cerebral artery flow velocity (MCAv) in a cohort of TIA patients (n = 17), and age‐matched controls (n = 15). Spontaneous fluctuations in BP and MCAv were characterized by spectral power analysis, and CBF regulation was assessed by wavelet phase synchronization analysis in the very low‐ (0.02–0.07 Hz), low‐ (0.07–0.20 Hz), and high‐frequency (0.20–0.40 Hz) ra...
Source: Physiological Reports - November 4, 2015 Category: Physiology Authors: Philip D. Allan, James Faulkner, Terrence O'Donnell, Jeremy Lanford, Lai‐kin Wong, Saqib Saleem, Brandon Woolley, Danielle Lambrick, Lee Stoner, Yu‐Chieh Tzeng Tags: Original Research Source Type: research

Application of vibration to wrist and hand skin affects fingertip tactile sensation
This study further examined this behavior by investigating the effect of both imperceptible and perceptible white‐noise vibration applied to different locations within the distal upper extremity on the fingertip pads' tactile sensation in healthy adults. In 12 healthy adults, white‐noise vibration was applied to one of four locations (dorsum hand by the second knuckle, thenar and hypothenar areas, and volar wrist) at one of four intensities (zero, 60%, 80%, and 120% of the sensory threshold for each vibration location), while the fingertip sensation, the smallest vibratory signal that could be perceived on the thumb an...
Source: Physiological Reports - July 14, 2015 Category: Physiology Authors: Kishor Lakshminarayanan, Abigail W. Lauer, Viswanathan Ramakrishnan, John G. Webster, Na Jin Seo Tags: Original Research Source Type: research

Sex comparisons in muscle sympathetic nerve activity and arterial pressure oscillations during progressive central hypovolemia
Abstract Increased tolerance to central hypovolemia is generally associated with greater sympathoexcitation, high‐frequency oscillatory patterns of mean arterial pressure (MAP), and tachycardia. On average, women are less tolerant to central hypovolemia than men; however, the autonomic mechanisms governing these comparisons are not fully understood. We tested the hypothesis that women with relatively high tolerance (HT) to central hypovolemia would display similar physiological reserve capacity for sympathoexcitation and oscillations in MAP at presyncope compared to HT men. About 10 men and five women were exposed to pro...
Source: Physiological Reports - June 24, 2015 Category: Physiology Authors: Robert Carter, Carmen Hinojosa‐Laborde, Victor A. Convertino Tags: Original Research Source Type: research

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