In the light of the occurrence of l-lactate dehydrogenase inside the mitochondrial matrix, we looked at whether isolated rat liver mitochondria can take up and metabolize l-lactate, and provide oxaloacetate outside mitochondria, thus contributing to a partial reconstruction of gluconeogenesis in vitro. We found that: (1) l-lactate (10 mM), added to mitochondria in the presence of a cocktail of glycolysis/gluconeogenesis enzymes and cofactors, can lead to synthesis of glyceraldehyde-3-phosphate at a rate of about 7 nmol/min per mg mitochondrial protein. (2) Three novel translocators exist to mediate l-lactate traffic across the inner mitochondrial membrane. An l-lactate/H+ symporter was identified by measuring fluorimetrically the rate of endogenous pyridine nucleotide reduction. Consistently, l-lactate oxidation was found to occur with P/O ratio=3 (where P/O ratio is the ratio of mol of ATP synthesized to mol of oxygen atoms reduced to water during oxidative phosphorylation) and with generation of membrane potential. Proton uptake, which occurred as a result of addition of l-lactate to RLM together with electron flow inhibitors, and mitochondrial swelling in ammonium l-lactate solutions were also monitored. l-Lactate/oxaloacetate and l-lactate/pyruvate anti-porters were identified by monitoring photometrically the appearance of l-lactate counter-anions outside mitochondria. These l-lactate translocators, which are distinct from the monocarboxylate carrier, were found to differ from each other in Vmax values and in inhibition and pH profiles, and proved to regulate mitochondrial l-lactate metabolism in vitro. The role of lactate/mitochondria interactions in gluconeogenesis is discussed.
Skip Nav Destination
Follow us on Twitter @Biochem_Journal
Article navigation
Research Article|
May 15 2004
Partial reconstruction of in vitro gluconeogenesis arising from mitochondrial l-lactate uptake/metabolism and oxaloacetate export via novel l-lactate translocators
Lidia de BARI;
Lidia de BARI
*Istituto di Biomembrane e Bioenergetica, CNR, Via G. Amendola, 165/A 70126 Bari, Italy
Search for other works by this author on:
Anna ATLANTE;
Anna ATLANTE
*Istituto di Biomembrane e Bioenergetica, CNR, Via G. Amendola, 165/A 70126 Bari, Italy
Search for other works by this author on:
Daniela VALENTI;
Daniela VALENTI
*Istituto di Biomembrane e Bioenergetica, CNR, Via G. Amendola, 165/A 70126 Bari, Italy
Search for other works by this author on:
Salvatore PASSARELLA
Salvatore PASSARELLA
1
†Dipartimento di Scienze Animali, Vegetali e dell'Ambiente, Università del Molise, Via De Sanctis 86100 Campobasso, Italy
1To whom correspondence should be addressed (e-mail [email protected]).
Search for other works by this author on:
Publisher: Portland Press Ltd
Received:
December 23 2003
Revision Received:
February 10 2004
Accepted:
February 11 2004
Accepted Manuscript online:
February 11 2004
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London ©2004
2004
Biochem J (2004) 380 (1): 231–242.
Article history
Received:
December 23 2003
Revision Received:
February 10 2004
Accepted:
February 11 2004
Accepted Manuscript online:
February 11 2004
Citation
Lidia de BARI, Anna ATLANTE, Daniela VALENTI, Salvatore PASSARELLA; Partial reconstruction of in vitro gluconeogenesis arising from mitochondrial l-lactate uptake/metabolism and oxaloacetate export via novel l-lactate translocators. Biochem J 15 May 2004; 380 (1): 231–242. doi: https://doi.org/10.1042/bj20031981
Download citation file:
Sign in
Don't already have an account? Register
Sign in to your personal account
You could not be signed in. Please check your email address / username and password and try again.
Could not validate captcha. Please try again.
Biochemical Society Member Sign in
Sign InSign in via your Institution
Sign in via your InstitutionGet Access To This Article
Follow us on Twitter @Biochem_Journal
Open Access for all
We offer compliant routes for all authors from 2025. With library support, there will be no author nor reader charges in 5 journals. Check here |
![]() View past webinars > |