Abstract P1084: Mature Ipsc-derived Atrial Cardiomyocytes Show That Saturated Fatty Acids Differentially Modulate Atrial Remodeling In Obesity-induced Atrial Fibrillation Compared To Mono And Poly-unsaturated Fatty Acids.

Background: Increased free fatty acids (FFA) and FA infiltration, both major hallmarks of obesity can individually modulate changes leading to AF. For example, mass spectrometry on obese mouse heart tissues have shown that saturated FAs (SFA), monounsaturated FAs (MUFA), and polyunsaturated FAs (PUFA) are all significantly increased compared to controls. The highest increase was shown to be in linoleic acid (LA), a PUFA followed by palmitic acid (PA, SFA) and oleic acid (OA, MUFA). Although reports suggest that some FAs induce ventricular arrhythmias in mice, the differential electrophysiological effects of SFAs, MUFAs, and PUFAs on the atria remain unclear. Objective: To determine the individual roles of SFAs, MUFAs, and PUFAs in mediating atrial remodeling in obesity-induced AF using mature human induced pluripotent stem-derived atrial cardiomyocytes (iPSC-aCMs). Methods: We compared iPSC-aCMs and HL-1 cells treated with bovine serum albumin (BSA) with palmitic acid (PA), oleic acid (OA) and LA cells (600 uM each) for 24 hours and 1 week. Ion channel function were assessed using optical voltage mapping and whole-cell patch clamping, and we assessed atrial remodeling using qPCR, and western blotting. Results: iPSC-aCMs treated with PA, OA, and LA displayed higher expression of FABP3 and CPT1A suggesting increased FA metabolism (Figure A-C). In HL1 cells, protein expression of Cpt1a was increased in all groups after FA treatment (Figure D). PA differentially modulated expression of Kv7.1 and NCX1 in HL1 cells (Figure E-F) and ion channel mRNA expression in iPSC-aCMs (Figure G-L). After 1 week PA and LA treatment b-adrenergic signaling was significantly increased in iPSC-aCMs while OA decreased it compared to controls (Figure M-O). Lastly, 24-hour PA, OA, LA treatment differentially modulated the atrial action potential (AP). While PA and LA significantly shorten the action potential, there was no significant changes to the AP after OA treatment. Conclusions: Using mature iPSC-aCMs, we showed for the first time that SFA, MUFA, and PUFA not only increased FA metabolism but differentially affected b-adrenergic signaling and ion channel remodeling leading to differential effects on the atrial AP. Our findings may have important implications for the management of obesity-induced AF in patients.