Atenolol

Isoprenaline hydrochloride, atenolol and verapamil hydrochloride were purchased from Abcam (Cambridge, UK). Dobutamine hydrochloride, digoxin and flecainide acetate were purchased from Tocris Bioscience (Oxford, UK). Stock solutions (1–10 mM) of all compounds were made and were stored at −20 °C. digoxin and dobutamine were dissolved in dimethyl sulfoxide (DMSO) to make the stock solution. The final concentration of DMSO during experimentation was less than 0.01%. Verapamil, atenolol, flecainide and isoprenaline were all dissolved in ultra-pure water to make the stock solution. All other reagents were purchased from either Sigma Aldrich (Dorset, UK) or Fisher Scientific (Loughborough, UK) unless stated otherwise.

Atenolol (99% pure), betaxolol (96% pure), esmolol (98% pure), timolol (99% pure) and pindolol (99% pure) were purchased from Abcam (Cambridge, UK), metoprolol (98% pure) was purchased from Alfa Aesar (Ward Hill, MA, USA), and propranolol (99% pure) was purchased from Acros Organic (Morris Plains, NJ, USA). All tested compounds were dissolved in dimethylsulfoxide (DMSO, ≥99%, Ph. Eur.) which was obtained from Sigma-Aldrich Co. (St. Louis, MO, USA).
TrypLE Express, Dulbecco’s modified Eagle high glucose medium (DMEM GlutaMAX), fetal bovine serum (FBS), penicillin/streptomycin solution (10,000 IU/mL), and phosphate buffered saline (PBS, pH = 7.4) were purchased from Gibco (Carlsbad, CA, USA). The aqueous 16% paraformaldehyde solution (PFA), the Hoechst 33342 (1 mg/mL) solution, and the Propidium iodide (1 mg/mL) solution were obtained from Thermo Fisher Scientific (Heysham, UK).
3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT, ≥97%) and crystal violet (≥90%) were purchased from Sigma-Aldrich Co. (St. Louis, MO, USA). Ethanol (96.6%) was obtained from Stumbras, LLC (Kaunas, Lithuania).
All cell culture plastic ware was purchased from Thermo Fisher Scientific, Corning (Phoenix, AZ, USA) and Techno Plastic Products (Trasadingen, Switzerland).