That third receptor is glucagon, and it changes the game a bit
The purpose of this review is to comprehensively investigate of the emerging understanding of the pleiotropic role of the carnitine pool, carnitine/acylcarnitines are not only auxiliaries or metabolites of fatty acid oxidation, but also play more complex and diverse roles, including energy metabolism, mitochondrial homeostasis, epigenetic regulation, regulation of inflammation and the immune system, tumor biology, signal transduction, and neuroprotection
NSL literature pointer PMID 7917283 L-Carnitine laboratory index [PMID: 7917283] National Science Labs indexing note for PMID 7917283: review the PubMed methods, models, and limitations before citing
Dietary and postprandial oxidative stress
Euro J Pharmacol 720:6368
Ahmed MS, Abed M, Voelkl J, Lang F