POLYMORPHISM OF PLASMA TRIGLYCERIDE KINETICS IN NORMAL HUMAN ADULT SUBJECTS
| Autor: | Esko A. Nikkilä, Matti Kekki |
|---|---|
| Rok vydání: | 2009 |
| Předmět: |
Adult
Glycerol Male medicine.medical_specialty Population Kinetics 030209 endocrinology & metabolism 030204 cardiovascular system & hematology Tritium Michaelis–Menten kinetics 03 medical and health sciences chemistry.chemical_compound Sex Factors 0302 clinical medicine Internal medicine Internal Medicine medicine Humans education Molecular Biology Triglycerides chemistry.chemical_classification education.field_of_study Triglyceride Computers business.industry Body Weight Middle Aged Cholesterol Enzyme Endocrinology chemistry Biochemistry Turnover Female Chromatography Thin Layer business Hormone |
| Zdroj: | Acta Medica Scandinavica. 190:49-59 |
| ISSN: | 0001-6101 |
| Popis: | Plasma triglyceride turnover has been measured in 34 adult healthy human volunteers selected on the basis of normal serum cholesterol and triglyceride concentrations and a normal b.wt. The circulating triglyceride was labelled in vivo with tritiated glycerol and the disappearance of radioactivity was followed up to 24 h. The descending part of the slope was divided into exponential components with the aid of a computer and the one-exponential resolutions were used for analysis. The enzymatic nature of the triglyceride removal mechanism was confirmed. When it was assumed that all subjects have a common maximal removal velocity (Vmax) level, calculation of Km values indicated that the population under study is definitely composed at least of two and perhaps of three groups. The next analysis was therefore carried out without any presumptions and the conventional enzyme kinetic plots were drawn. These revealed that the two groups differ in regard to Vmax but not to Km. Two of the subjects did not fit into either of these groups. Group I with a higher Vmax had a significantly higher turnover rate than group II, which showed a rather uniform distribution of both turnover rate and concentration. The two groups had identical age, sex and b.wt. distribution. There was a definite difference in the triglyceride kinetics between males and females. Both had identical turnover rates, but females showed a lower Km and, correspondingly, a lower plasma concentration of triglyceride. The well known difference in plasma triglyceride concentration between men and fertile-aged women is thus accounted for by the more efficient removal system in the latter. It is concluded that the plasma triglyceride concentration in any individual and under any conditions is determined by three factors: (1) the turnover (synthesis) rate, (2) the maximal removal velocity (Vmax), and (3) the Michaelis constant (Km) of the removal enzyme(s). All of these may be influenced by factors like diet, hormones, metabolites and drugs, but obviously the first two are also genetically determined. It is suggested that any classification of hypertriglyceridemias should include an enzyme kinetic analysis, and this will be attempted in the studies in progress. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|