Abstract
The purpose of the present study was to compare the plasma insulin levels in portal
and peripheral veins in rats submitted to a prolonged exercise to exhaustion (x̄±SE:
67 ± 7 min). Plasma insulin levels were reduced significantly (p < 0.01) during exercise
in both the portal and peripheral venous circulation. The reduction was, however,
more pronounced in the portal than in the peripheral vein(x̄: - 113 vs - 64 and -
162 vs - 88 pmol·1-1 after 30 and 45 min of exercise, respectively), indicating that exercise reduced
not only insulin secretion but also its removal. Accordingly, no significant differences
were found for the portal/peripheral ratio of insulin at rest and during the first
45 min of exercise (1.86±0.2, 1.76±0.1, and 1.57±0.2 at rest, and after 30 and 45
min of exercise, respectively). This suggests that insulin removal during exercise
is regulated in proportion to portal insulin concentrations.
Key words
Portal insulin - portal/peripheral ratio
