[The impact of Sorbs2 on the progression of ventricular arrhythmias in mice].

Objective: To investigate the impact potential mechanisms of Sorbin and SH3 domain-containing protein 2 (Sorbs2) on ventricular arrhythmias in mice. Methods: In the animal experiments, mating was performed using six 8-week-old Sorbs2^+/- mice (3 males and 3 females) weighing 20-22 g. Wild-type (Sorbs2^+/+, n=8) and homozygous (Sorbs2^-/-, n=6) offspring were selected as experimental subjects through genotyping. Echocardiography was performed at 16 weeks of age to record cardiac function parameters in both groups. Resting-state and caffeine-dobutamine-induced electrocardiograms were also conducted. Real-time quantitative reverse transcription polymerase chain reaction was used to detect Sorbs2 messager RNA expression in the heart, liver, spleen, lung, kidney, brain, small intestine, and skeletal muscle tissues of wild-type mice. Western blotting was employed to measure the protein expression levels of Sorbs2 and voltage-dependent sodium channel alpha subunit 1.5 (Na_v1.5) in myocardial tissues from both groups. In the cell experiments, H9C2 cells were transfected with Sorbs2 small interfering RNA as the si-Sorbs2 group, with a corresponding si-negative control group established. Western blot was performed to detect the protein expression levels of Sorbs2 and Nav1.5 in both groups. Results: Sorbs2 was abundantly expressed in cardiac tissue. Compared with wild-type mice, homozygous mice exhibited larger left ventricular end-systolic diameter, along with lower left ventricular ejection fraction and fractional shortening (P all<0.05). Resting-sate electrocardiograms revealed no spontaneous arrhythmias in either group; however, homozygous mice showed shorter RR intervals but longer QRS and QTc intervals versus wild-type mice (P all<0.05). Following caffeine and dobutamine induction, homozygous mice demonstrated a higher incidence of ventricular arrhythmias, longer arrhythmia duration, and higher ventricular arrhythmia scores than wild-type mice (P all<0.05). Western blot analysis revealed that Na_v1.5 protein expression was markedly lower in myocardial tissues of homozygous mice compared to wild-type mice. Similarly, si-Sorbs2-transfected H9C2 cells exhibited lower Na_v1.5 protein levels compared to the si-negative control group (P<0.05). Conclusion: Sorbs2 plays a critical role in maintaining normal cardiac electrophysiological function. Deficiency of Sorbs2 may lead to impaired cardiac function and increased susceptibility to ventricular arrhythmias in mice, which could be associated with reduced expression of Nav1.5 protein.