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Ono M, Burgess DE, Johnson SR, Elayi CS, Esser KA, Seward TS, Boychuk CR, Carreño AP, Stalcup RA, Prabhat A, Schroder EA, Delisle BP. Feeding behavior modifies the circadian variation in RR and QT intervals by distinct mechanisms in mice. Am J Physiol Regul Integr Comp Physiol 2024; 327:R109-R121. [PMID: 38766772 DOI: 10.1152/ajpregu.00025.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 05/09/2024] [Accepted: 05/09/2024] [Indexed: 05/22/2024]
Abstract
Rhythmic feeding behavior is critical for regulating phase and amplitude in the ≈24-h variation of heart rate (RR intervals), ventricular repolarization (QT intervals), and core body temperature in mice. We hypothesized changes in cardiac electrophysiology associated with feeding behavior were secondary to changes in core body temperature. Telemetry was used to record electrocardiograms and core body temperature in mice during ad libitum-fed conditions and after inverting normal feeding behavior by restricting food access to the light cycle. Light cycle-restricted feeding modified the phase and amplitude of 24-h rhythms in RR and QT intervals, and core body temperature to realign with the new feeding time. Changes in core body temperature alone could not account for changes in phase and amplitude in the ≈24-h variation of the RR intervals. Heart rate variability analysis and inhibiting β-adrenergic and muscarinic receptors suggested that changes in the phase and amplitude of 24-h rhythms in RR intervals were secondary to changes in autonomic signaling. In contrast, changes in QT intervals closely mirrored changes in core body temperature. Studies at thermoneutrality confirmed that the daily variation in QT interval, but not RR interval, primarily reflected daily changes in core body temperature (even in ad libitum-fed conditions). Correcting the QT interval for differences in core body temperature helped unmask QT interval prolongation after starting light cycle-restricted feeding and in a mouse model of long QT syndrome. We conclude feeding behavior alters autonomic signaling and core body temperature to regulate phase and amplitude in RR and QT intervals, respectively.NEW & NOTEWORTHY We used time-restricted feeding and thermoneutrality to demonstrate that different mechanisms regulate the 24-h rhythms in heart rate and ventricular repolarization. The daily rhythm in heart rate reflects changes in autonomic input, whereas daily rhythms in ventricular repolarization reflect changes in core body temperature. This novel finding has major implications for understanding 24-h rhythms in mouse cardiac electrophysiology, arrhythmia susceptibility in transgenic mouse models, and interpretability of cardiac electrophysiological data acquired in thermoneutrality.
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Affiliation(s)
- Makoto Ono
- Department of Physiology, University of Kentucky, Lexington, Kentucky, United States
| | - Don E Burgess
- Department of Physiology, University of Kentucky, Lexington, Kentucky, United States
| | - Sidney R Johnson
- Department of Physiology, University of Kentucky, Lexington, Kentucky, United States
| | - Claude S Elayi
- CHI Saint Joseph Hospital, Lexington, Kentucky, United States
| | - Karyn A Esser
- Department of Physiology and Aging, University of Florida, Gainesville, Florida, United States
| | - Tanya S Seward
- Department of Physiology, University of Kentucky, Lexington, Kentucky, United States
| | - Carie R Boychuk
- Department of Biomedical Sciences, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri, United States
| | - Andrés P Carreño
- Department of Physiology, University of Kentucky, Lexington, Kentucky, United States
| | - Rebecca A Stalcup
- Department of Physiology, University of Kentucky, Lexington, Kentucky, United States
| | - Abhilash Prabhat
- Department of Physiology, University of Kentucky, Lexington, Kentucky, United States
| | - Elizabeth A Schroder
- Department of Physiology, University of Kentucky, Lexington, Kentucky, United States
- Department of Internal Medicine, University of Kentucky, Lexington, Kentucky, United States
| | - Brian P Delisle
- Department of Physiology, University of Kentucky, Lexington, Kentucky, United States
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Ono M, Burgess DE, Johnson SR, Elayi CS, Esser KA, Seward TS, Boychuk CR, Carreño AP, Stalcup RA, Prabhat A, Schroder EA, Delisle BP. Feeding Behavior Modifies the Circadian Variation in RR and QT intervals by Distinct Mechanisms in Mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.02.565372. [PMID: 37961515 PMCID: PMC10635091 DOI: 10.1101/2023.11.02.565372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Rhythmic feeding behavior is critical for regulating the phase and amplitude in the ≍24-hour variation of the heart rate (RR intervals), ventricular repolarization (QT intervals), and core body temperature in mice. We hypothesized the changes in cardiac electrophysiology associated with feeding behavior were secondary to changes in core body temperature. Telemetry was used to record electrocardiograms and core body temperature in mice during ad libitum-fed conditions and after inverting normal feeding behavior by restricting food access to the light cycle. Light cycle-restricted feeding quickly modified the phase and amplitude of the 24-hour rhythms in RR intervals, QT intervals, and core body temperature to realign with the new feeding time. Heart rate variability analysis and inhibiting β-adrenergic and muscarinic receptors suggested that the changes in the phase and amplitude of the 24-hour rhythms in RR intervals were secondary to changes in autonomic signaling. In contrast, the changes in the QT intervals closely mirrored changes in core body temperature. Studies at thermoneutrality confirmed the daily variation in the QT interval, but not the RR interval, and reflected daily changes in core body temperature (even in ad libitum-fed conditions). Correcting the QT interval for differences in core body temperature helped to unmask QT interval prolongation after starting light cycle-restricted feeding and in a mouse model of long QT syndrome. We conclude feeding behavior alters autonomic signaling and core body temperature to regulate the phase and amplitude in RR and QT intervals, respectively.
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Zhu M, Lu J, Li X, An Y, Li B, Liu W. Ivabradine Alleviates Experimental Autoimmune Myocarditis-Mediated Myocardial Injury. Int Heart J 2024; 65:109-118. [PMID: 38296563 DOI: 10.1536/ihj.23-330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2024]
Abstract
Ivabradine (IVA) reduces heart rate by inhibiting hyperpolarization-activated cyclic nucleotide-gated channels (HCNs), which play a role in the promotion of pacemaker activity in cardiac sinoatrial node cells. HCNs are highly expressed in neural and myocardial tissues and are involved in the modulation of inflammatory neuropathic pain. However, whether IVA exerts any effect on myocardial inflammation in the pathogenesis of heart failure is unclear. We employed single-cell RNA sequencing (scRNA-seq) in porcine cardiac myosin-induced experimental autoimmune myocarditis rat model to determine the effects and mechanisms of IVA. Lewis rats (n = 32) were randomly divided into the normal, control, high-dose-IVA, and low-dose-IVA groups. Heart rate and blood pressure were measured on days 0 and 21, respectively. Echocardiography was performed on day 22, and inflammation of the myocardium was evaluated via histopathological examination. Western blot was employed to detect the expression of HCN1-4, MinK-related protein 1 (MiRP1), matrix metalloproteinase 2 (MMP-2), MMP-9, and transforming growth factor-β (TGF-β). Furthermore, enzyme-linked immunosorbent assay was performed to measure serum IL-1, IL-6, and TNF-α. The relative mRNA levels of collagen I, collagen III, and α-smooth muscle actin (α-SMA) were determined via qRT-PCR. We found that IVA reduced the total number of cells infiltrated into the myocardium, particularly in the subset of fibroblasts, endocardia, and monocytes. IVA administration ameliorated cardiac inflammation and reduced collagen production. Results of the echocardiography indicated that left ventricular internal diameter at end-systole LVIDs increased whereas left ventricular ejection fraction and left ventricular fractional shortening decreased in the control group. IVA improved cardiac performance. The expression of HCN4 and MiRP1 protein and the level of serum IL-1, IL-6, and TNF-α were decreased by IVA treatment. In conclusion, HCNs and the helper proteins were increased in the profile of myocardial inflammation. HCNs may be involved in the regulation of myocardial inflammation by inhibiting immune cell infiltration. Our findings can contribute to the development of IVA-based combination therapies for the future treatment of cardiac inflammation and heart failure.
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Affiliation(s)
- Manlin Zhu
- Department of Cardiology, Fourth Affiliated Hospital, Harbin Medical University
| | - Jingjing Lu
- Department of Cardiology, Fourth Affiliated Hospital, Harbin Medical University
| | - Xiaomin Li
- Department of Cardiology, Fourth Affiliated Hospital, Harbin Medical University
| | - Yongqiang An
- Department of Cardiology, First Affiliated Hospital, Hebei Medical University
| | | | - Wei Liu
- Department of Cardiology, Fourth Affiliated Hospital, Harbin Medical University
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