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Aberrant sinus node firing during β‐adrenergic stimulation leads to cardiac arrhythmias in diabetic mice
Author(s) -
Lubberding Anniek F.,
Pereira Laetitia,
Xue Jianbin,
Gottlieb Lisa A.,
Matchkov Vladimir V.,
Gomez Ana M.,
Thomsen Morten B.
Publication year - 2020
Publication title -
acta physiologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.591
H-Index - 116
eISSN - 1748-1716
pISSN - 1748-1708
DOI - 10.1111/apha.13444
Subject(s) - isoprenaline , medicine , carbachol , atropine , endocrinology , diabetes mellitus , heart rate , adrenergic , autonomic nervous system , baroreflex , stimulation , cardiology , blood pressure , receptor
Aim Cardiovascular complications, including cardiac arrhythmias, result in high morbidity and mortality in patients with type‐2 diabetes mellitus (T2DM). Clinical and experimental data suggest electrophysiological impairment of the natural pacemaker of the diabetic heart. The present study examined sinoatrial node (SAN) arrhythmias in a mouse model of T2DM and physiologically probed their underlying cause. Methods Electrocardiograms were obtained from conscious diabetic db/db and lean control db/+ mice. In vivo SAN function was probed through pharmacological autonomic modulation with isoprenaline, atropine and carbachol. Blood pressure stability and heart rate variability (HRV) were evaluated. Intrinsic SAN function was evaluated through ex vivo imaging of spontaneous Ca 2+ transients in isolated SAN preparations. Results While lean control mice showed constant RR intervals during isoprenaline challenge, the diabetic mice experienced SAN arrhythmias with large RR fluctuations in a dose‐dependent manner. These arrhythmias were completely abolished by atropine pre‐treatment, while carbachol pretreatment significantly increased SAN arrhythmia frequency in the diabetic mice. Blood pressure and HRV were comparable in db/db and db/+ mice, suggesting that neither augmented baroreceptor feedback nor autonomic neuropathy is a likely arrhythmia mechanism. Cycle length response to isoprenaline was comparable in isolated SAN preparations from db/db and db/+ mice; however, Ca 2+ spark frequency was significantly increased in db/db mice compared to db/+ at baseline and after isoprenaline. Conclusion Our results demonstrate a dysfunction of cardiac pacemaking in an animal model of T2DM upon challenge with a β‐adrenergic agonist. Ex vivo, higher Ca 2+ spark frequency is present in diabetic mice, which may be directly linked to in vivo arrhythmias.