Changes of serum apolipoprotein levels after oral administration of fat in human subjects.
Changes of serum apolipoprotein levels were studied every hour for 6 h after the administration of 55 g butter to 8 healthy male subjects. The mean serum apo A-IV level was significantly increased at 4 h (P less than 0.05) after fat ingestion compared to the mean initial level, although no significant changes of levels in other apolipoproteins (apo A-I, A-II, B, C-II, C-III, and E) were observed. The mean apo A-IV level in the triglyceride-rich lipoprotein (TRL) fraction (d less than 1.006) increased progressively over 6 h. In all 8 subjects, the time of peak concentration of apo A-IV in TRL fraction was delayed by 1-2 h compared to that in whole serum. On the other hand, the mean apo B-48 level in the fraction reached a peak at 4 h. These results raise the possibilities that some apo A-IV, newly synthesized or already existing in intestinal cells, may be directly secreted into the venous circulation and that apo A-IV and apo B-48 may distribute differently in different sizes of chylomicron. Alternatively, the amount of each apolipoprotein synthesized may depend upon the content of ingested fat. It is suggested that apo A-IV production by intestinal cells does not appear to be regulated by the rate of fat transport, and that apo A-IV does not play an important role in chylomicron formation compared to apo B-48.
Seishima
M
M
Department of Laboratory Medicine, Gifu University School of Medicine, Japan.
Noma
A
A
Torizawa
H
H
Muto
Y
Y
D000284:Administration, Oral; D000328:Adult; D053283:Apolipoprotein B-48; D001053:Apolipoproteins / Q000097:blood*; D001054:Apolipoproteins A / Q000097:blood; D001055:Apolipoproteins B / Q000097:blood; D002079:Butter; D006801:Humans; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000378:metabolism; D008297:Male; D013997:Time Factors
D053283:Apolipoprotein B-48; D001053:Apolipoproteins; D001054:Apolipoproteins A; D001055:Apolipoproteins B; C022205:apolipoprotein A-IV; D002079:Butter