relative to glucose infusion. Blood samples were allowed
to coagulate for 30 min, and then centrifuged at 1,500
× g for 20 min. Serum was decanted and stored at −20°C
for future analysis.
Glucose and insulin analyses were conducted using
the methods already described. The interassay coefficient
of variation for insulin was 3.3% with 101% recovery.
Baseline glucose and insulin concentrations were
determined using preinfusion concentrations from time
−1 and 0 min. Glucose half-life was estimated for each
animal by regressing the logarithmically transformed
glucose concentrations over time (Kaneko, 1989). Area
under the curve was determined for insulin and glucose
concentrations using the trapezoidal summation
method.