Respiratory sinus arrhythmia (RSA) may improve the efficiency of pulmonary gas exchange by matching the pulmonary blood flow to lung volume during each respiratory cycle. If so, an increased demand for pulmonary gas exchange may enhance RSA magnitude. We therefore tested the hypothesis that CO2 directly affects RSA in conscious humans even when changes in tidal volume (V(T)) and breathing frequency (F(B)), which indirectly affect RSA, are prevented. In seven healthy subjects, we adjusted end-tidal PCO2 (PET(CO2)) to 30, 40, or 50 mmHg in random order at constant V(T) and F(B). The mean amplitude of the high-frequency component of R-R interval variation was used as a quantitative assessment of RSA magnitude. RSA magnitude increased progressively with PET(CO2) (P < 0.001). Mean R-R interval did not differ at PET(CO2) of 40 and 50 mmHg but was less at 30 mmHg (P < 0.05). Because V(T) and F(B) were constant, these results support our hypothesis that increased CO2 directly increases RSA magnitude, probably via a direct effect on medullary mechanisms generating RSA.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1152/ajpheart.00554.2001 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Measurement of the root surface area in rat molars through three-dimensional modeling.
Arch Oral Biol
November 2024
State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China. Electronic address:
Objectives: Rats are used as animal models for basic and applied research related to orthodontic tooth movement (OTM). The magnitude of mechanical force in OTM rat models mainly depends on the supporting capability of the periodontal ligament (PDL), which is highly associated with the root surface area (RSA). But the size of rat RSA remains unknown, which is the reason why there are still debates on the magnitude of mechanical force in OTM rat models.
View Article and Find Full Text PDFQuantification of respiratory sinus arrhythmia in control dogs and in dogs with various severity classes of myxomatous mitral valve disease.
J Vet Cardiol
October 2024
Cardiology Service, Veterinary Teaching Hospital, Koret School of Veterinary Medicine, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Israel, P.O. Box 12, Rehovot, 76100, Israel.
Introduction: Loss of respiratory sinus arrhythmia (RSA) is a negative prognostic factor in dogs with myxomatous mitral valve disease (MMVD). The aim of this study was to calculate the percentage (%) of RSA in healthy dogs and dogs in various MMVD classes.
Animals: Control and MMVD dogs were prospectively included in the study.
Manipulating and measuring variation in deep neural network (DNN) representations of objects.
Cognition
November 2024
Department of Psychology, Vanderbilt University, USA.
We explore how DNNs can be used to develop a computational understanding of individual differences in high-level visual cognition given their ability to generate rich meaningful object representations informed by their architecture, experience, and training protocols. As a first step to quantifying individual differences in DNN representations, we systematically explored the robustness of a variety of representational similarity measures: Representational Similarity Analysis (RSA), Centered Kernel Alignment (CKA), and Projection-Weighted Canonical Correlation Analysis (PWCCA), with an eye to how these measures are used in cognitive science, cognitive neuroscience, and vision science. To manipulate object representations, we next created a large set of models varying in random initial weights and random training image order, training image frequencies, training category frequencies, and model size and architecture and measured the representational variation caused by each manipulation.
View Article and Find Full Text PDFStemless reverse shoulder arthroplasty neck shaft angle influences humeral component time-zero fixation and survivorship: a cadaveric biomechanical assessment.
JSES Int
July 2024
The Roth|McFarlane Hand and Upper Limb Centre, St. Joseph's Hospital, London, ON, Canada.
Background: Stemless humeral components are being clinically investigated for reverse shoulder arthroplasty (RSA) procedures. There is, however, a paucity of basic science literature on the surgical parameters that influence the success of these procedures. Therefore, this cadaveric biomechanical study evaluated the neck shaft angle (NSA) of implantation on the survivability and performance of stemless RSA humeral components during cyclical loading.
View Article and Find Full Text PDFRSA instability in mothers of preschoolers and adolescents is related to observations of supportive parenting behaviors.
Dev Psychobiol
July 2024
Department of Psychology, University of Georgia, Athens, Georgia, USA.
Respiratory sinus arrhythmia (RSA; a measure of respiratory modulation of vagal control of heart rate) is a dynamic process. For mothers, RSA functioning has been associated with depressive symptoms and coincides with supportive parenting. However, research has largely focused on RSA suppression (i.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!