Dose-kinetics of pancreatic alpha- and beta-cell responses to a protein meal in normal subjects.
A protein meal is well known to induce a prompt secretion of insulin and glucagon. However, the data regarding the dose-response relationship between the protein meal and the insulin and glucagon responses are sparse. This study assessed the effects of ingestion of protein meals of varying amounts on plasma glucose [S], insulin [I], and glucagon [G] concentrations in eight normal subjects. Protein meals were administered after an overnight fast in a randomized sequence at intervals of 10 days in four different quantities: 250 mg/kg body weight (BW) (A), 500 mg/kg BW (B), 1 g/kg BW (C), and 2 g/kg BW (D). Mean S levels were not significantly altered following A, B, or C, although significant decreases in S responses were noted after C and D as reflected by absolute changes (delta) and/or the cumulative responses (CR) and the areas under the curve (sigma). Mean I increased promptly to peak concentration by 30 minutes, although in individual subjects the peak was achieved either at 30 or 60 minutes following all protein meals. The increase was progressively greater and the return was delayed with increasing quantities resulting in progressive elevations in delta I and percent increase from basal concentration (%), as well as CRI and sigma I. G increased following all protein meals as well. The mean peak G concentrations were achieved by 90 minutes, although in individual subjects the peak G was reached at 90 or 120 minutes, a significant delay in comparison to the peak I levels. G returned to base line only following ingestion of A during the study period.(ABSTRACT TRUNCATED AT 250 WORDS)
Kabadi
U M
UM
Medical Service, VA Medical Center, Des Moines, IA.
D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D004044:Dietary Proteins / Q000493:pharmacokinetics / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005934:Glucagon / Q000097:blood; D006801:Humans; D007328:Insulin / Q000097:blood; D007515:Islets of Langerhans / Q000187:drug effects*; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D013997:Time Factors
D001786:Blood Glucose; D004044:Dietary Proteins; D007328:Insulin; D005934:Glucagon