Fluvoxamine rescues mitochondrial Ca2 + transport and ATP production through σ1-receptor in hypertrophic cardiomyocytes

AimsWe previously reported that fluvoxamine, a selective serotonin reuptake inhibitor with high affinity for the σ1-receptor (σ1R), ameliorates cardiac hypertrophy and dysfunction via σ1R stimulation. Although σ1R on non-cardiomyocytes interacts with the IP3 receptor (IP3R) to promote mitochondrial Ca2 + transport, little is known about its physiological and pathological relevance in cardiomyocytes.Main methodsHere we performed Ca2 + imaging and measured ATP production to define the role of σ1Rs in regulating sarcoplasmic reticulum (SR)-mitochondrial Ca2 + transport in neonatal rat ventricular cardiomyocytes treated with angiotensin II to promote hypertrophy.Key findingThese cardiomyocytes exhibited imbalances in expression levels of σ1R and IP3R and impairments in both phenylephrine-induced mitochondrial Ca2 + mobilization from the SR and ATP production. Interestingly, σ1R stimulation with fluvoxamine rescued impaired mitochondrial Ca2 + mobilization and ATP production, an effect abolished by treatment of cells with the σ1R antagonist, NE-100. Under physiological conditions, fluvoxamine stimulation of σ1Rs suppressed intracellular Ca2 + mobilization through IP3Rs and ryanodine receptors (RyRs). In vivo, chronic administration of fluvoxamine to TAC mice also rescued impaired ATP production.SignificanceThese results suggest that σ1R stimulation with fluvoxamine promotes SR-mitochondrial Ca2 + transport and mitochondrial ATP production, whereas σ1R stimulation suppresses intracellular Ca2 + overload through IP3Rs and RyRs. These mechanisms likely underlie in part the anti-hypertrophic and cardioprotective action of the σ1R agonists including fluvoxamine.