Gluconeogenesis and the pyruvate transporter

Halestrap initially concluded that the increases in mitochondrial pyruvate transport and carboxylation were due to an increase in A pH secondary to stimulation of the electron transport chain in the cytochrome fee, region [255]. The conclusion was based largely on spectral measurements of the redox state of these cytochromes in the control and stimulated states. The spectral measurements were later found to be artifactual due to low amplitude Ca swelling of the mitochondria. Halestrap then suggested that the stable changes in the mitochondria might reside in the lipid components of the membrane due to phospholipase A 2 activity [261,262], but he has been unable to confirm this with lysophospholipid measurements [263]. On the other hand, using an EPR spin label probe of the lipid environment of the isolated mitochondria, Hoek has found differences between control and treated mitochondria [264]. 

Despite these findings, other data suggest that mitochondrial membranes may be a target for glucagon emd phenylephrine action. Measurements of metabolite gradients in situ have shown that endogenous adenine nucleotide levels are increased by 

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