Effects of a four-day hyperinsulinemic-euglycemic clamp in early and mid-lactation dairy cows on plasma concentrations of metabolites, hormones, and binding proteins.
The effects of insulin, using a 4 d hyperinsulinemic-euglycemic clamp, on plasma concentrations of hormone, metabolites, and binding proteins were evaluated in four Holstein dairy cows during wk 4 and 17 of lactation. Insulin was infused at 1 microg/kg/hr for 96 hr during the clamp period. Compared with the pre-clamp period, plasma insulin concentrations increased 7-fold and 4-fold during the clamp periods in early and mid-lactation, respectively. The total amount of glucose infused was higher (P < 0.05) during the clamp in early lactation. The clamp decreased plasma concentrations of non-esterified fatty acids (P < 0.001) during early lactation while differences in mid-lactation were minor. The clamp also decreased plasma concentration of beta-hydroxybutyrate (P < 0.001), plasma urea nitrogen (P < 0.001), and true protein (P < 0.01) although the patterns of decline differed between early and mid-lactation. Growth hormone (GH) concentrations decreased (P < 0.001) and insulin-like growth factor-1 (IGF-1) increased (P < 0.01) during the clamp period suggesting a direct effect of insulin on the un-coupling of the GH/IGF-1 axis. Levels of IGF binding protein-2 (IGFBP-2) decreased (P < 0.01) during the clamp period. The relative proportion of IGFBP-2 decreased (P < 0.001) and that of IGFBP-3 increased (P < 0.001) during the clamp period. There were no interactions between the clamp period and stage of lactation on GH, IGF-1, or IGFBPs. Overall, most plasma variables measured were affected in the same way during the two clamps, but the pattern of change often varied with stage of lactation.
Mashek
D G
DG
Danish Institute of Agricultural Sciences, Department of Animal Health and Welfare, Research Centre Foulum, P.O. Box 50, DK-8830 Tjele, Denmark.
Ingvartsen
K L
KL
Andersen
J B
JB
Vestergaard
M
M
Larsen
T
T
D020155:3-Hydroxybutyric Acid / Q000097:blood; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001806:Blood Urea Nitrogen; D002118:Calcium / Q000097:blood; D002417:Cattle / Q000097:blood* / Q000502:physiology; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005947:Glucose / Q000008:administration & dosage / Q000494:pharmacology*; D015309:Glucose Clamp Technique; D013006:Growth Hormone / Q000097:blood; D007328:Insulin / Q000008:administration & dosage / Q000097:blood* / Q000494:pharmacology; D018969:Insulin-Like Growth Factor Binding Proteins / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007774:Lactation / Q000378:metabolism*; D016018:Least-Squares Analysis; D008274:Magnesium / Q000097:blood; D010758:Phosphorus / Q000097:blood
D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D018969:Insulin-Like Growth Factor Binding Proteins; D010758:Phosphorus; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D008274:Magnesium; D005947:Glucose; D002118:Calcium; D020155:3-Hydroxybutyric Acid