Distribution and transport of varied substances in the dog kidney in vivo: implications with regard to metabolic activities.

Some matters bearing on renal metabolic activities have been reviewed. The distribution of solutes to various regions of the kidneys depends not only on convection by blood and tissue fluid flow but also on diffusion of the solutes in the tissues. Lipid solubility may play a significant role in tissue diffusion in that substances with significant lipid solubility may have access to more direct pathways than strictly hydrophilic substances. Glucose utilization by the kidney is significant. Glucose may contribute as much as 25 per cent and lactate, through decarboxylation, as much as 30 per cent of the renal carbon dioxide production. Together, glucose and lactate may account for about 50 per cent of the total renal carbon dioxide production. There is evidence that there is substantial lactate production by the kidney as well as gluconeogenesis. The conditions for luminal and anti-luminal cell surface interactions with D-glucose differ with regard to configuration, conformation and phlorizin affinity. Possible pathways of entry of glucose into metabolic activities are briefly considered.