ISRN Physiology The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. Effects of Nitrate Supplementation on Cardiovascular and Autonomic Reactivity in African-American Females Sun, 23 Feb 2014 08:05:23 +0000 Previous studies have shown that beetroot juice (BJ) decreases systolic blood pressure (SBP) and oxygen demand. This study tests the hypothesis that a beetroot juice (BJ) treatment increases heart rate variability (HRV) measured by the average standard deviation of normal-normal electrocardiogram RR intervals (SDNN) and the low frequency (LF), mainly sympathetic, fast Fourier transform spectral index of HRV. The subjects were 13 healthy young adult African-American females. Placebo control orange juice (OJ) and BJ treatments were given on separate days. Blood nitric oxide [NO], SBP and RR intervals were measured at rest and at constant workloads set to 40% and 80% of the predetermined . Two hours after ingestion the BJ treatment increased [NO] and decreased SBP. BJ also increased SDNN at rest and at the 40% workload, without significant effects on LF. SDNN was significantly greater after the BJ than after the OJ treatment, across the two physical activity conditions and SDNN was (negatively) correlated with SBP. These results suggest that BJ decreases SBP and increases HRV at rest and during aerobic exercise. Similar results in subjects with prehypertension or hypertension could translate to a dietary nitrate treatment for hypertension. Vernon Bond, Bryan H. Curry, R. George Adams, M. Sadegh Asadi, Kimani A. Stancil, Richard M. Millis, and Georges E. Haddad Copyright © 2014 Vernon Bond et al. All rights reserved. Exercise-Induced Biological and Psychological Changes in Overweight and Obese Individuals: A Review of Recent Evidence Thu, 06 Feb 2014 13:47:57 +0000 On a global scale, the most recent evidence indicates that over 400 million adults are obese while ~20 million children and 1.6 billion adults are overweight. The World Health Organization reveals that, by the year 2015, ~2.3 billion adults will be overweight and more than 700 million will be obese. In this review paper we summarized the current evidence to elucidate the impact of exercise training on biological and psychological health indices in overweight and obese individuals. Endocrine function indices that are discussed herein include leptin, adiponectin, growth hormone, and ghrelin levels. Psychological factors include anxiety and depression, body image, and motivation for exercise. Overall, exercise promotes physical and psychological health in overweight and obese individuals particularly because exercise-induced adaptations occur across a multitude of systems within the active human. The impact of exercise on specific biological and psychological health indices contributes to overall health in overweight and obese individuals. Petros C. Dinas, Aleksandra S. Markati, and Andres E. Carrillo Copyright © 2014 Petros C. Dinas et al. All rights reserved. High Density Lipoprotein: Assembly, Structure, Cargo, and Functions Wed, 25 Dec 2013 12:02:51 +0000 Cardiovascular disease (CVD) is the leading cause of death globally. For close to four decades, we have known that high density lipoprotein (HDL) levels are inversely correlated with the risk of CVD. HDL is a complex particle that consists of proteins, phospholipids, and cholesterol and has the ability to carry micro-RNAs. HDL is constantly undergoing remodelling throughout its life-span and carries out many functions. This review summarizes many of the different aspects of HDL from its assembly, the receptors it interacts with, along with the functions it performs and how it can be altered in disease. While HDL is a key cholesterol efflux particle, this review highlights the many other important functions of HDL in the innate immune system and details the potential therapeutic uses of HDL outside of CVD. Andrew J. Murphy Copyright © 2013 Andrew J. Murphy. All rights reserved. Signalling in Neutrophils: A Retro Look Thu, 07 Nov 2013 08:06:21 +0000 This review presents a summary of signalling events related to the activation of human polymorphonuclear neutrophils by a variety of soluble and particulate agonists. It is not intended as a comprehensive review of this vast field or as a presentation of the multiple new aspects of neutrophil functions that are being documented at an ever faster rate. Its aim is rather to focus on multiple aspects of major signalling pathways that, in the view of this reviewer, are currently shadowed by present trends and to provide the core evidence for their implication and the limitations of our present knowledge. More specifically, this review starts with cell surface receptors and some of their functional and biological properties and then moves on to downstream transducers (G proteins) and effectors (the phosphoinositide, tyrosine kinases, and cyclic nucleotide pathways). Classical second messengers (calcium, protein kinase C, polyphosphoinositides, and cyclic nucleotides) are emphasized. It is hoped that this presentation will not only remind present-day investigators of the central role these pathways play in the regulation of the functional responsiveness of neutrophils, but that it will also highlight some of the areas deserving additional investigation. Paul H. Naccache Copyright © 2013 Paul H. Naccache. All rights reserved. Oxygen Consumption at 30 W of Exercise Is Surrogate for Peak Oxygen Consumption in Evaluation of Cardiorespiratory Fitness in Young-Adult African-American Females Wed, 09 Oct 2013 09:07:46 +0000 Body mass index (BMI) is negatively correlated with cardiorespiratory fitness, measured by maximal or peak oxygen consumption (). measurements require heavy aerobic exercise to near exhaustion which increases the potential for adverse cardiovascular events. This study tests the hypothesis that measured at a fixed submaximal workload of 30 W is a surrogate for . We studied 42 normotensive African-American female university students, 18–25 years of age. We measured , blood pressure, and at a 30 W exercise workload and computed BMI. We found significant negative correlations between BMI and (, ) and between BMI and at 30 W (, ). Compared to , at 30 W increased the significance of the negative correlation with BMI. The heart rate-systolic pressure product at 30 W was positively correlated with BMI (, ) and negatively correlated with (, ). The positive correlation between BMI and the heart rate-systolic pressure product and the greater negative correlation between and BMI at 30 W of exercise than that at exercise to fatigue suggest that normalized measurements of at the fixed exercise workload of 30 W could be useful surrogates for measurements of . Richard M. Millis, Vernon Bond Jr., M. Sadegh Asadi, Georges E. Haddad, and Richard G. Adams Copyright © 2013 Richard M. Millis et al. All rights reserved. Differences in Expression and Function in the Atrium versus Ventricle of the Sodium-Calcium Exchanger in the Embryonic Chicken Heart Sun, 01 Sep 2013 14:31:57 +0000 Heart function is well known to be dependent on intrinsic electrical activity. This electrical activity is primarily mediated by a combination of interactions among various ionic channels and transporters. In this study, we demonstrate that the Na+-Ca2+ exchanger (NCX) is equally present in both atrial and ventricular cells at early stages of development (st. 13). However, ventricular cells exhibit an increase in NCX messenger ribonucleic acid (mRNA) levels during later stages of development, while levels in atrial cells remain constant. We demonstrate that the current density of the NCX increases with development in the ventricle but remains constant in the atrial cells. Furthermore we demonstrate that the NCX has a major role in shaping the cardiac action potential at early stages mainly in ventricular cells (st. 14) than later mainly in the atrial cells (st. 30). Luis Polo-Parada and Amol A. Modgi Copyright © 2013 Luis Polo-Parada and Amol A. Modgi. All rights reserved. The Coronary Microcirculation in Health and Disease Mon, 15 Jul 2013 14:05:41 +0000 Coronary blood flow is closely regulated to meet the changing metabolic demands of the working myocardium. Resistance of the coronary vasculature is determined by metabolic, myogenic, endothelial, and neural mechanisms. The influence of these control mechanisms varies throughout the coronary circulation, as they have dominant sites of action in vessels of different caliber. Coronary vascular resistance depends upon the coordinated response to these influences. Within a segment of the coronary circulation, resistance may be determined, for example, by competitive interaction between neural vasoconstriction and metabolic vasodilation. Such a system in which control occurs through multiple mechanisms with varying effects allows for precise control of coronary blood flow. This system also provides protection against dysfunction of a single control mechanism. If one fails, other control mechanisms can compensate for that loss of function. Thus, adequate delivery of oxygen and nutrients can be maintained despite potential dysfunction and large fluctuations in metabolic demands of the myocardium. In disease states, these regulatory mechanisms may also fail, and endothelial dysfunction is commonly seen in the setting of cardiac disease. Optimal cardioprotective therapies must target the coronary microcirculation and cardiac myocytes in tandem. Similarly, reversal of cardiac dysfunction requires concomitant amelioration of coronary microvascular dysfunction. Judy M. Muller-Delp Copyright © 2013 Judy M. Muller-Delp. All rights reserved. Macromolecule Permeability in Rodent Intestine following Thermal Injury and Lipopolysaccharide Challenge Sun, 14 Jul 2013 08:03:50 +0000 The barrier function of the intestinal mucosa may be lost during stress such as severe trauma and sepsis. The present study utilized a multicannulated (jugular vein, proximal jejunum, thoracic duct, and portal vein) rat model of burn (30% body surface area (TBSA)) and endotoxemia (E. coli lipopolysaccharide (LPS) infused via the jugular cannula) to investigate in vivo barrier function to macromolecules with different sizes and the route for their transport (horse radish peroxidase (HRP) and 14C-polyethylene glycol (PEG)-4,000 infused via jejunal cannula). In burn rats, mucosa uptakes of HRP and PEG increased 3 h after their intraluminal infusion compared to the controls. Studies with intravenous 111In-IgG infusion showed that its recovery in small intestine was decreased after burn and LPS infusion, indicating that blood perfusion to intestine was compromised. The present study suggests that (1) burn and endotoxemia increase intestinal permeability to macromolecules; (2) the portal blood may be the major route of transport for molecules up to sizes of 4,000 during burn but not endotoxemia; and (3) intestinal hypoperfusion could be one of the factors that contribute to increased gut permeability in severe burn trauma and sepsis. Peirong Yu and Edward A. Carter Copyright © 2013 Peirong Yu and Edward A. Carter. All rights reserved. Brain Physiology and Pathophysiology in Mental Stress Sun, 09 Jun 2013 14:09:27 +0000 Exposure to various forms of stress is a common daily occurrence in the lives of most individuals, with both positive and negative effects on brain function. The impact of stress is strongly influenced by the type and duration of the stressor. In its acute form, stress may be a necessary adaptive mechanism for survival and with only transient changes within the brain. However, severe and/or prolonged stress causes overactivation and dysregulation of the hypothalamic pituitary adrenal (HPA) axis thus inflicting detrimental changes in the brain structure and function. Therefore, chronic stress is often considered a negative modulator of the cognitive functions including the learning and memory processes. Exposure to long-lasting stress diminishes health and increases vulnerability to mental disorders. In addition, stress exacerbates functional changes associated with various brain disorders including Alzheimer’s disease and Parkinson’s disease. The primary purpose of this paper is to provide an overview for neuroscientists who are seeking a concise account of the effects of stress on learning and memory and associated signal transduction mechanisms. This review discusses chronic mental stress and its detrimental effects on various aspects of brain functions including learning and memory, synaptic plasticity, and cognition-related signaling enabled via key signal transduction molecules. Karim Alkadhi Copyright © 2013 Karim Alkadhi. All rights reserved. Role of Candidate Genes Regulating Uterine Prostaglandins Biosynthesis for Maternal Recognition of Pregnancy in Domestic Animals Sun, 19 May 2013 16:17:49 +0000 The survivability and opportunity of successful development of an embryo are influenced directly or indirectly by factors controlling uterine microenvironment. Out of all factors, hormones such as prostaglandins (PGs) released during the preimplantation period influence molecular interactions involved in maintenance of pregnancy through reciprocal interactions between the conceptus and endometrium. PGs are important regulators of female reproductive functions, namely, ovulation, uterine receptivity, implantation, and parturition. Among different classes of PGs, prostaglandin F2α (PGF2α) and prostaglandin E2 (PGE2) are main prostanoids produced by human and bovine endometrium for successful growth and development of the posthatching blastocyst. In ruminants, PGF2α produced by endometrium is the major luteolytic agent, whereas PGE2 has luteoprotective and antiluteolytic properties. Therefore, the development and maintenance of the corpus luteum (CL), as well as establishment of pregnancy, depend on the balance of luteolytic PGF2α and luteotropic PGE2. In this review, we discussed the expression and function of genes which predominantly regulate the synthesis and their secretion of PGF2α and PGES, namely, PGFS (AKR1B5/AKR1C3), PGES, PGFR, and COX-2. Rohit Kumar, P. W. Ramteke, Amar Nath, R. Kumar Pramod, Satyendra P. Singh, Sanjeev Kumar Sharma, and Sandeep Kumar Copyright © 2013 Rohit Kumar et al. All rights reserved. Structural and Functional Properties of Venous Wall: Relationship between Elastin, Collagen, and Smooth Muscle Components and Viscoelastic Properties Thu, 16 May 2013 15:31:13 +0000 The aims of this work were (1) to analyze the viscoelastic behavior of different venous segments and their differences, considering the structural characteristics (elastin, collagen, and smooth muscle content) of the venous wall; (2) to analyze the venous biomechanical behavior by means of the histological characteristics of the veins. Nine healthy male Corriedale sheep were included. One vein was selected from each animal to evaluate its biomechanical properties: (a) anterior vena cava, (b) right jugular vein, and (c) right femoral vein. Each selected vein was instrumented with pressure and diameter sensors. After excision, a small ring-shaped sample was set apart from each segment for histological analysis. The amounts of elastin, collagen and smooth muscle were correlated to calculated biomechanical parameters (high- and low-pressure compliance and viscosity). Conclusions are the following: (1) the viscoelastic behavior of the venous wall varies depending on the vascular territory, and it is associated with the variation of the histological structure. These differences involve muscle (both smooth and striated), elastin, and collagen contents. (2) In addition, the quantity of collagen was negatively correlated with high- and low-pressure compliances, and (3) the smooth muscle content was higher in peripheral veins and is positively correlated with venous wall viscosity. Yanina Zócalo, Daniel Bia, Edmundo I. Cabrera-Fischer, Sandra Wray, Cintia Galli, and Ricardo L. Armentano Copyright © 2013 Yanina Zócalo et al. All rights reserved. Neurophysiological Basis of Sleep’s Function on Memory and Cognition Mon, 08 Apr 2013 09:53:31 +0000 A wealth of recent studies support a function of sleep on memory and cognitive processing. At a physiological level, sleep supports memory in a number of ways including neural replay and enhanced plasticity in the context of reduced ongoing input. This paper presents behavioral evidence for sleep’s role in selective remembering and forgetting of declarative memories, in generalization of these memories, and in motor skill consolidation. Recent physiological data reviewed suggests how these behavioral changes might be supported by sleep. Importantly, in reviewing these findings, an integrated view of how distinct sleep stages uniquely contribute to memory processing emerges. This model will be useful in developing future behavioral and physiological studies to test predictions that emerge. Rebecca M. C. Spencer Copyright © 2013 Rebecca M. C. Spencer. All rights reserved. Physiology and Pathophysiology of the Biliary Tract: The Gallbladder and Sphincter of Oddi—A Review Sun, 24 Feb 2013 17:16:02 +0000 The biliary tract collects, stores, concentrates, and delivers bile secreted by the liver. Its motility is controlled by neurohormonal mechanisms with the vagus and splanchnic nerves and the hormone cholecystokinin playing key roles. These neurohormonal mechanisms integrate the motility of the gallbladder and sphincter of Oddi (SO) with the gastrointestinal tract in the fasting and digestive phases. During fasting most of the hepatic bile is diverted toward the gallbladder by the resistance of the SO. The gallbladder allows the gradual entry of bile relaxing by passive and active mechanisms. During the digestive phase the gallbladder contracts, and the SO relaxes allowing bile to be released into the duodenum for the digestion and absorption of fats. Pathological processes manifested by recurrent episodes of upper abdominal pain affect both the gallbladder and SO. The gallbladder motility and cytoprotective functions are impaired by lithogenic hepatic bile with excess cholesterol allowing the hydrophobic bile salts to induce chronic cholecystitis. Laparoscopic cholecystectomy is the standard treatment. Three types of SO dyskinesia also cause biliary pain. Their pathophysiology is not completely known. The pain of types I and II usually respond to sphincterotomy, but the pain due to type III usually does not. Jose Behar Copyright © 2013 Jose Behar. All rights reserved. VO2 Kinetics during Moderate Effort in Muscles of Different Masses and Training Level Mon, 31 Dec 2012 14:11:50 +0000 Purpose. To examine the relative importance of central or peripheral factors in the on-transient VO2 response dynamics to exercise with “trained” and relatively “untrained” muscles. Methods. Seven professional road cyclists and seven elite kayak paddlers volunteered to participate in this study. Each completed two bouts of constant-load “square-wave” rest-to-exercise transition cycling and arm-cranking exercise at a power output 50–60% of the mode-specific VO2peak presented in a randomized order. Results. In the cyclists, the mean response time (MRT) as well as the phase II VO2 time constant () was significantly slower in the untrained compared with the trained muscles. The opposite was the case in the kayakers. With respect to the relatively untrained muscle groups, while both demonstrated faster VO2 kinetics than normal (moderately fit) subjects, the kayakers evidenced faster VO2 kinetics than the cyclists. This suggests that there is a greater stabilizing-counterforce involvement of the legs in the task of kayaking than of the arms for cycling. Conclusions. The results of the present study provide no support for the “transfer” of a training effect onto the VO2 on-transient response for moderate exercise, but rather support earlier reports demonstrating that peripheral effects may be important in dictating this kinetics. Omri Inbar, Marcello Faina, Sabrina Demarie, and Brian J. Whipp Copyright © 2012 Omri Inbar et al. All rights reserved. Influence of Resistance Training Variables on Excess Postexercise Oxygen Consumption: A Systematic Review Wed, 05 Dec 2012 12:15:23 +0000 Objectives. Resistance training may influence the resting metabolic rate (RMR), which is desirable in weight management programs. However, its impact on excess postexercise oxygen consumption (EPOC) is yet to be defined. The study evaluated the contribution of resistance training variables to EPOC. Design. Studies published until November 2011 were systematically reviewed. Methods. MEDLINE, LILACS, SCIELO, Science Citation Index, Scopus, SPORTDiscus, and CINAHL databases were consulted. The methodological quality of studies was assessed by the PEDro 10-point scale. A total of 155 participants (54% men) aged between and years were observed by 16 studies (quality scores ranged from 5 to 7), which were organized according to treatment similarity (number of sets, intensity, rest interval, speed of movement, and exercise order). Results. Training volume seemed to influence both EPOC magnitude and duration, whereas workload influenced mostly the magnitude. Short rest intervals (<60 s) increased the EPOC magnitude, but not the overall energy expenditure. Conclusion. Resistance training with high intensity and volume, performed with short rest intervals (as in circuit training), probably have greater impact on EPOC. Methodological procedures, particularly time of post-exercise observation and RMR assessment, should be standardized to an appropriate quantification of the actual influence of resistance training on EPOC. Paulo Farinatti, Antonio Gil Castinheiras Neto, and Nádia Lima da Silva Copyright © 2013 Paulo Farinatti et al. All rights reserved. Reduced Muscle Glycogen Differentially Affects Exercise Performance and Muscle Fatigue Mon, 03 Dec 2012 10:34:39 +0000 This investigation examined the effects of reduced muscle glycogen on exercise performance and muscle fatigue. Male rats were assigned to a low glycogen group (LG) that participated in a protocol of exercise and fasting, a high glycogen group (HG) that exercised but were allowed free access to food, or control group (CON) that did not exercise but were allowed free access to food. Following the protocol, muscle glycogen content of the LG animals was reduced by 45%. The LG animals also performed 79 and 81% less voluntary treadmill exercise than the HG and CON groups. At exhaustion, the LG group had lower blood glucose than HG and CON but exhibited no reduction in sarcoplasmic reticulum (SR) function. During 30 min of in situ stimulation, the rates and magnitudes of muscle fatigue were not significantly different between groups, and fatigue-induced reductions in SR function were similar between groups. The results indicate that reduced muscle glycogen markedly impairs voluntary exercise performance but does not appreciably affect isolated muscle function. It is likely that exercise exhaustion due to reduced muscle glycogen is due, in large part, to hypoglycemia and central fatigue as opposed to peripheral mechanisms. Jay H. Williams, Timothy W. Batts, and Simon Lees Copyright © 2013 Jay H. Williams et al. All rights reserved. Acute Activation of the Renal Betaine/GABA Transporter in Response to a Decrease in Extracellular Calcium Mon, 05 Nov 2012 11:12:41 +0000 The betaine/GABA transporter (BGT1) is important for osmoprotection in kidney medullary cells. We previously reported an acute (30 min) increase in extracellular Ca2+ caused dose dependent inhibition of BGT-1 in renal MDCK cells. To determine if extracellular Ca2+ might be a local regulator of BGT-1, we have tested the response to low Ca2+ serum-free growth medium (LCM, 0.05 mM Ca2+). Chronic treatment (8–24 h) of MDCK cell monolayers completely blocked hypertonic adaptation of BGT1 and disrupted tight junctions. In contrast, acute treatment activated BGT1 transport within 30 min in MDCK cells previously adapted to hypertonic growth medium containing normal Ca2+ (1.6 mM). Activation was significant after 60–90 min and was independent of medium osmolarity. Peak transport was increased 50% in isotonic LCM and 100% in hypertonic (500 mOsm) LCM over controls. The activation was reversed by restoration of normal Ca2+. Perfusion of Fura-2-loaded MDCK cells with LCM decreased intracellular Ca2+ by 31% within 6-7 min. Inclusion of staurosporine (0.6 μM), a protein kinase C inhibitor, potentiated the action of LCM. We suggest that activation of BGT1 by LCM may be due in part to inhibition of protein kinase C. Nehal R. Parikh, Cherissa L. Vaughn, Lagina L. Williams, and Stephen A. Kempson Copyright © 2013 Nehal R. Parikh et al. All rights reserved.