Renal Energy Metabolism Following Acute Dichloroacetate and 2,4-Dinitrophenol Administration: Assessing the Cumulative Action with Hyperpolarized [1-13C]Pyruvate MRI

Abstract

Numerous patient groups receive >1 medication and as such represent a potential point of improvement in today's healthcare setup, as the combined or cumulative effects are difficult to monitor in an individual patient. Here we show the ability to monitor the pharmacological effect of 2 classes of medications sequentially, namely, 2,4-dinitrophenol, a mitochondrial uncoupler, and dichloroacetate, a pyruvate dehydrogenase kinase inhibitor, both targeting the oxygen-dependent energy metabolism. We show that although the 2 drugs target 2 different metabolic pathways connected ultimately to oxygen metabolism, we could distinguish the 2 in vivo by using hyperpolarized [1-¹³C]pyruvate magnetic resonance imaging. A statistically significantly different pyruvate dehydrogenase flux was observed by reversing the treatment order of 2,4-dinitrophenol and dichloroacetate. The significance of this study is the demonstration of the ability to monitor the metabolic cumulative effects of 2 distinct therapeutics on an in vivo organ level using hyperpolarized magnetic resonance imaging.

Keywords: 2,4-DNP; DCA; MRI; hyperpolarization; metabolism.

Figure 1.

Time line. Experimental time line of the hyperpolarized examination. Three consecutive [1-¹³C]pyruvate examinations were performed to estimate the changes associated with treatment with 2,4-Dinitrophenylhydrazine (2,4-DNP) and dichloroacetate (DCA) and their cumulative combination.

Figure 2.

Representative images of the ¹³C lactate-to-pyruvate signal changes. The lactate/pyruvate changes associated with the treatment with either 2,4-DNP and then afterwards DCA (top row) or DCA and then 2,4-DNP (bottom row). The color bar represents the change from baseline.

Figure 3.

The comparison of metabolic pathways and oxygen consumption alterations associated with cumulative treatment with 2,4-DNP and DCA. The hyperpolarized metabolic profile and the treatment pattern of lactate, alanine, and bicarbonate normalized to pyruvate was both significantly different (P < .0001) (A). No difference was found with respect to time alone (P = .13), the interaction terms (metabolite × treatment) (P = .56), (metabolite × time) (P = .9), and (metabolite × treatment × time) (P = .6). However the effect of treatment with time (treatment × time) was found to be significantly different (P = .0008). A significant effect was observed in the basal respiration over time (P = .01), but not cumulative between the 2 treatment patterns (P = .13) (B). A significant interaction term (time x treatment) was seen (P = .01). The data are represented as mean ± SD.

Figure 4.

Individual parameters for proton leak, maximal respiration, and adenosine triphosphate (ATP) production. Proton leak is the difference in oxygen consumption rate (OCR) after oligomycin injection and antimycin A/rotenone. Maximal respiration is the OCR after carbonyl cyanide m-chlorophenylhydrazone (CCCP) injection and antimycin A/rotenone. ATP production is the difference in OCR before and after oligomycin. The data are represented as mean ± SEM.