scholarly journals CrossTalk opposing view: Bradycardia in the trained athlete is attributable to a downregulation of a pacemaker channel in the sinus node

2015 ◽  
Vol 593 (8) ◽  
pp. 1749-1751 ◽  
Author(s):  
Alicia D'Souza ◽  
Sanjay Sharma ◽  
Mark R. Boyett
Keyword(s):  
Sinus Node ◽  
Trained Athlete ◽  
Opposing View ◽  
Pacemaker Channel

scholarly journals Mouse models for studying pacemaker channel function and sinus node arrhythmia

2008 ◽  
Vol 98 (2-3) ◽  
pp. 179-185 ◽  
Author(s):  
Andreas Ludwig ◽  
Stefan Herrmann ◽  
Evelyn Hoesl ◽  
Juliane Stieber
Keyword(s):  
Mouse Models ◽  
Sinus Node ◽  
Channel Function ◽  
Pacemaker Channel

scholarly journals Pacemaker channel dysfunction in a patient with sinus node disease

2003 ◽  
Vol 111 (10) ◽  
pp. 1537-1545 ◽  
Author(s):  
Eric Schulze-Bahr ◽  
Axel Neu ◽  
Patrick Friederich ◽  
U. Benjamin Kaupp ◽  
Günter Breithardt ◽  
...  
Keyword(s):  
Sinus Node ◽  
Pacemaker Channel ◽  
Node Disease ◽  
Sinus Node Disease

scholarly journals Circadian control of intrinsic heart rate via a sinus node clock and the pacemaker channel

2019 ◽  
Author(s):  
Yanwen Wang ◽  
Servé Olieslagers ◽  
Anne Berit Johnsen ◽  
Svetlana Mastitskaya ◽  
Haibo Ni ◽  
...  
Keyword(s):  
Heart Rate ◽  
Circadian Rhythm ◽  
Circadian Clock ◽  
Clock Genes ◽  
Sinus Node ◽  
Ionic Current ◽  
Luciferase Reporter ◽  
Local Clock ◽  
Intrinsic Heart Rate ◽  
Pacemaker Channel

ABSTRACTIn the human, there is a circadian rhythm in the resting heart rate and it is higher during the day in preparation for physical activity. Conversely, slow heart rhythms (bradyarrhythmias) occur primarily at night. Although the lower heart rate at night is widely assumed to be neural in origin (the result of high vagal tone), the objective of the study was to test whether there is an intrinsic change in heart rate driven by a local circadian clock. In the mouse, there was a circadian rhythm in the heart rate in vivo in the conscious telemetrized animal, but there was also a circadian rhythm in the intrinsic heart rate in denervated preparations: the Langendorff-perfused heart and isolated sinus node. In the sinus node, experiments (qPCR and bioluminescence recordings in mice with a Per1 luciferase reporter) revealed functioning canonical clock genes, e.g. Bmal1 and Per1. We identified a circadian rhythm in the expression of key ion channels, notably the pacemaker channel Hcn4 (mRNA and protein) and the corresponding ionic current (funny current, measured by whole cell patch clamp in isolated sinus node cells). Block of funny current in the isolated sinus node abolished the circadian rhythm in the intrinsic heart rate. Incapacitating the local clock (by cardiac-specific knockout of Bmal1) abolished the normal circadian rhythm of Hcn4, funny current and the intrinsic heart rate. Chromatin immunoprecipitation demonstrated that Hcn4 is a transcriptional target of BMAL1 establishing a pathway by which the local clock can regulate heart rate. In conclusion, there is a circadian rhythm in the intrinsic heart rate as a result of a local circadian clock in the sinus node that drives rhythmic expression of Hcn4. The data reveal a novel regulator of heart rate and mechanistic insight into the occurrence of bradyarrhythmias at night.

The Philological Endeavours of the Early Arabic Linguists: Theological Implications of the tawqīf-iṣṭilāḥ Antithesis and the majāz Controversy – Part I

1999 ◽  
Vol 1 (1) ◽  
pp. 27-46 ◽  
Author(s):  
Mustafa Shah
Keyword(s):  
Opposing View ◽  
Religious Doctrine ◽  
Origin Of Language ◽  
The Way

This article examines a number of issues relating to discussions of the origin of language and related topics among early Arabic linguists. A number of these discussions treated the topic of the ‘revelationist’ view of language (tawqīf), and the opposing view that language had developed as a result of human convention (iṣṭilāḥ). It has been suggested that religious doctrine hampered the development of the linguistic tradition, as theologically motivated views increasingly governed the way in which linguists were able to articulate their positions on this and related subjects. We contend that the evidence does not altogether support this view, and that there was a subtle interplay between theological views and linguistic theories. Individual linguists, whom tradition identifies as having certain theological tendencies, are found to have followed lines of linguistic thinking at odds with what is assumed to have been the religious doctrine to which they subscribed. An increasingly sophisticated tradition of scholarship refined and reassessed arguments based on the Qur'an and earlier thought, with a concern for the theological implications of issues such as ishtiqāq, tarāduf and addād.

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