The metabolism of glyceride-glycerol.

Various aspects of glycerol metabolism have been extensively investigated, both in vivo and in vitro, with the aid of isotopic glycerol. Experiments in vivo on the incorporation of C14-glycerol into glycogen and various body lipides, as well as its oxidation to C1402 have been reported (l-3). The metabolism of Ci4-glycerol by liver in vitro (4) and glycogen synthesis from deuterium-labeled glycerol (5) have also been studied. Recently there have been publications on some aspects of the metabolism of asymmetrically labeled glycerol (6-8). Further, glycerides synthesized from isotopically labeled glycerol have been utilized by many investigators as a tool in studying the mechanism of intestinal fat absorption (9-13). The purpose of the present investigation was to obtain information on the metabolism of the glycerol moiety of triglycerides, or “glyceride-glycerol.” Such a study should be germane since most of the glycerol that is normally ingested is esterified with fatty acids. Thus, data are presented on the oxidation of glyceride-glycerol and its incorporation into various lipide fractions of the gastrointestinal tract. In the light of the findings reported, the absorption and lipolysis of triglycerides are discussed. In addition, there are data on the incorporation of glyceride-glycerol carbon into plasma and liver lipides and into liver glycogen.