**Palmitate but Not Oleate Exerts a Negative E**ff**ect on Oxygen Utilization in Myoblasts of Patients with the m.3243A**>**G Mutation: A Pilot Study**

#### **Leila Motlagh Scholle 1, \*, Helena Schie**ff**ers 1 , Samiya Al-Robaiy 2 , Annemarie Thaele 1 , Diana Lehmann Urban <sup>3</sup> and Stephan Zierz 1**


Received: 5 August 2020; Accepted: 15 September 2020; Published: 16 September 2020

**Abstract:** It is known that exposure to excess saturated fatty acids, especially palmitate, can trigger cellular stress responses interpreted as lipotoxicity. The effect of excessive free fatty acids on oxidative phosphorylation capacity in myoblasts of patients with the m.3243A>G mutation was evaluated with the mitochondrial (Mito) stress test using a Seahorse XF96 analyzer. ß-oxidation, measured with the Seahorse XF96 analyzer, was similar in patients and controls, and reduced in both patients and controls at 40 ◦C compared to 37 ◦C. Mito stress test in the absence of fatty acids showed lower values in patients compared to controls. The mitochondrial activity and ATP production rates were significantly reduced in presence of palmitate, but not of oleate in patients, showing a negative effect of excessive palmitate on mitochondrial function in patients. Diabetes mellitus is a frequent symptom in patients with m.3243A>G mutation. It can be speculated that the negative effect of palmitate on mitochondrial function might be related to diacylglycerols (DAG) and ceramides (CER) mediated insulin resistance. This might contribute to the elevated risk for diabetes mellitus in m.3243A>G patients.

**Keywords:** fatty acid oxidation; palmitate; oleate; m.3243A>G mutation
