In vitro and in vivo lipogenesis of the rat renal papillae from glucose.
The rate of [14C]glucose incorportion into rat renal papillary glycerolipids has been studied. Glucose is incorported mainly into the glycerol moiety of these lipids. 74 and 93% of the activity incorporated into triacylglycerols in vitro and in vivo, respectively, was present in the glycerol backbone. In phospholipids it was 82 and 96%, respectively. The fatty acid synthesis from [14C]glucose was similar to that from [14C]acetate. In accordance with previous experiments with [14C]acetate the papillary tissue was found to have a high capacity for chain elongation of preexisting fatty acids with the major product being cis-7,10,13,16-docosatetraenoic acid (chain elongated arachidonic acid). The in vitro and in vivo turnover rates of papillary glycerolipids can be calculated. A half-life of 25 h can be estimated for membrane phospholipids and less than 11 h for lipid droplet triacylglycerols. These appreciably high rates of turnover are discussed in relation to membrane turnover in renal papillae from rats in different physiological states and to variation in number of lipid droplets of papillary interstitial cells reported by others.
D000818:Animals; D002849:Chromatography, Gas; D002855:Chromatography, Thin Layer; D005947:Glucose / Q000378:metabolism*; D066298:In Vitro Techniques; D007679:Kidney Medulla / Q000378:metabolism*; D008297:Male; D008563:Membrane Lipids / Q000096:biosynthesis; D010743:Phospholipids / Q000096:biosynthesis; D051381:Rats; D014280:Triglycerides / Q000096:biosynthesis*
D008563:Membrane Lipids; D010743:Phospholipids; D014280:Triglycerides; D005947:Glucose