Glutamine transport in dog kidney mitochondria: a new control mechanism in acidosis.

Experiments performed with isolated mitochondria from dog renal cortex provide evidence for a carrier for glutamine located in the inner mitochondrial membrane. This carrier transfers glutamine to glutaminase located in the inner membrane or matrix space and provides a site for regulation of glutamine metabolism and ammoniagenesis. Examination of glutamate formation by the carrier-glutaminase system in mitochondria and in submitochondrial preparations from acidotic and alkalotic dogs shows enhanced glutamate formation without accompanying alteration in glutaminase levels in preparations form acidotic animals. These findings suggest that the increased renal ammonia formation from glutamine during metabolic acidosis results from an adaptive increase in transport of glutamine by the inner membrane carrier.