Responses and molecular heterogeneity of IR-GIP after intraduodenal glucose and fat.
The plasma responses and molecular heterogeneity of human immunoreactive gastric inhibitory polypeptide (IR-GIP) after intraduodenal administration of equicaloric amounts of glucose (25 g) and fat (10 g) were determined with five different antisera. Two of these do not cross-react with 8 kdaltons (kDa) IR-GIP. In the fasting state plasma IR-GIP concentrations were highest measured with antisera, which detected both 5 and 8 kDa IR-GIP. The total integrated or incremental IR-GIP areas were similar after glucose and fat when determined with the same antiserum. When antisera with similar cross-reactivity with human 5 kDa IR-GIP were compared, no difference in incremental IR-GIP areas after either stimulus was found between antisera that did and did not measure 8 kDa IR-GIP. Gel filtration of plasma showed a consistent increase in 5 kDa IR-GIP 60 min after both glucose and fat but small and inconsistent changes in 8 kDa IR-GIP. Thus fat on a weight and molar basis is more potent than glucose in releasing IR-GIP. Both fat and glucose release predominantly the 5 kDa IR-GIP. Although of importance for the absolute IR-GIP level in plasma, 8 kDa IR-GIP contributes little to the increase in IR-GIP after both stimuli.
D000328:Adult; D002850:Chromatography, Gel; D003429:Cross Reactions; D004386:Duodenum; D005215:Fasting; D005223:Fats; D005260:Female; D005749:Gastric Inhibitory Polypeptide / Q000097:blood* / Q000378:metabolism; D005768:Gastrointestinal Hormones / Q000097:blood*; D005947:Glucose; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D007441:Intubation, Gastrointestinal; D008297:Male; D008970:Molecular Weight; D011863:Radioimmunoassay
D005223:Fats; D005768:Gastrointestinal Hormones; D007106:Immune Sera; D005749:Gastric Inhibitory Polypeptide; D005947:Glucose