The autonomic pathways mediating the bradycardia response to facial immersion (FI) have not been fully elaborated in man. By means of parasympathetic and sympathetic blockade we studied the heart rate response to FI in nine highly trained young swimmers, at rest and during dynamic cycle exercise. With no blockade, heart rate at rest declined with FI 36 +/- 18%. Under beta-blockade with propranolol or alpha-blockade with phentolamine FI produced a similar decrement. Atropine reduced the response. During exercise FI produced 48 +/- 9% decline without blockade. The response was similar with beta-blockade, but was completely abolished with atropine. Systolic blood pressure responses to FI measured by cuff in three subjects were small and bore no relation to the heart rate response. The results are compatible with parasympathetic efferent mediation of the heart rate response to FI. They are incompatible with a role for sympathetic mediation except as a complex interaction between parasympathetic and sympathetic influences. Hypertension and other sympathetic responses to FI do not play a role in production of bradycardia, but are apparently incidental effects. The heart rate decrement produced by FI increases with greater steady-state heart rate.
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http://dx.doi.org/10.1152/jappl.1979.47.6.1218 | DOI Listing |
Eur J Cardiothorac Surg
January 2025
Division of Cardiovascular Surgery, The Labatt Family Heart Centre, The Hospital for Sick Children, Toronto, ON, Canada.
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J Psychoactive Drugs
January 2025
Department of Psychiatry, Mathison Centre for Mental Health Research and Education, and Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.
The ever-changing landscape surrounding legality and accessibility of psychedelics and their increasing popularity make it imperative to better understand the nature of psychedelic use by the general population. To this end, 1,486 eligible respondents ( = 29.58, 67.
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January 2025
Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne, Australia.
Aim: To evaluate whether integrating Apolipoprotein B (ApoB) into the SCORE2 cardiovascular risk prediction framework improves its predictive accuracy and clinical applicability within the UK Biobank population.
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Curr Cardiol Rev
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Department of Nutrition, Société Francophone de Nutrithérapie et de Nutrigénétique Appliquée, Villeurbanne, France.
Objective: The usage of doxorubicin (DOX), an antineoplastic drug that is frequently used for the cure of cancer, is restricted to maximal doses due to its cardiac toxicity. Reactive oxygen species produced by DOX result in lipid peroxidation and organ failure, ultimately resulting in cardiomyopathy. Due to its high polyphenol content, virgin rice bran oil (VRBO) is a diet nutritional supplement with a strong antioxidant.
View Article and Find Full Text PDFFront Physiol
January 2025
Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan.
Measuring the heart rate of sea turtles is important for understanding their physiological adaptations to the environment. Non-invasive methods to measure the electrocardiogram (ECG) of sea turtles have been developed by attaching electrodes to their carapace. However, this method has only been applicable to sea turtles with sparse keratin on their shell surfaces, such as loggerhead turtles, and it is difficult to detect heartbeats in sea turtles with dense keratinous scutes, including green sea turtles.
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