TRPC6 deficiency attenuates cardiac mitochondrial dysfunction and HFpEF induced by chronic high-fat diet and inhibition of nitric oxide synthesis with L-NAME

Objective: Transient receptor potential canonical channel type 6 (TRPC6), a non-selective cation channel that mediates Ca 2+ influx, is expressed in the heart. Overexpression of TRPC6 has been suggested to participate in pathological cardiac hypertrophy. However, the role of excessive TRPC6 activation in the development of heart failure with preserved ejection fraction (HFpEF) and cardiac mitochondrial dysfunction is still not fully understood. We tested the hypothesis that TRPC6 deficiency may have a cardiac protective effect by attenuating mitochondrial-derived reactive oxygen species (ROS) generation and alleviating mitochondrial dysfunction in a mouse model of HFpEF. Methods: HFpEF was induced in TRPC6 knockout (KO) and wild-type (WT) control mice by feeding a high-fat diet (45% fat) for 12 consecutive weeks combined with N-omega-nitro-L-arginine methyl ester (L-NAME) (0.5 g/L in drinking water) added for the last 8 consecutive weeks. Cardiac systolic and diastolic functions were assessed using echocardiography under normal and dobutamine-induced stress conditions. Additionally, treadmill exercise test was performed to evaluate exercise tolerance. Mitochondrial oxygen consumption rate and mitochondrial-ROS generation were examined in isolated cardiac fibers using Oroboros Oxygraphy-2k respirometry. TRPC6 fractional protein expression levels in cytosol and mitochondria from left ventricle samples were also quantified. Results: WT mice developed diastolic dysfunction and cardiac hypertrophy after treatment with HFD+L-NAME, whereas TRPC6 KO mice exhibited preserved diastolic function (IVRT: 21.5±1.1 in WT vs 16.3±1.2 msec in TRPC6 KO, P <0.05). Dobutamine stress test showed that TRPC6 KO mice had a higher stroke volume and cardiac output at 10 min after injection than WT mice. TRPC6 KO mice also exhibited better exercise tolerance, higher mitochondrial oxygen consumption rate (136.7± 31.1 vs 101.1± 20.1 pmol/min/mg, P <0.05) and lower mitochondrial-ROS generation compared to WT mice. We found significantly increased TRPC6 expression in cytosol and mitochondria as well as caspase 9 activation in the left ventricle of WT mice after being treated with HFD+L-NAME, but not in TRPC6 KO mice. Conclusions: TRPC6 deficiency attenuated diastolic dysfunction while preserving cardiac reserve capacity, improved mitochondrial respiration, and reduced mitochondrial-ROS generation in an HFpEF model induced by HFD+L-NAME. Targeting TRPC6 and its downstream signaling pathways may offer a promising therapeutic approach for future HFpEF treatments. (NIDDK R00DK113280, 1R01HL163076, NIDDK 1R01DK121411, NIGMS P30GM104357 and U54GM115428) This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.