AJP - Endocrinology and Metabolism, Vol 242, Issue 6 373-E377, Copyright © 1982 by American Physiological Society
Potassium homeostasis during hyperinsulinemia: effect of insulin level, beta-blockade, and age
K. L. Minaker and J. W. Rowe
The euglycemic glucose clamp technique was used to evaluate the influence
of level and duration of hyperinsulinemia, presence of beta-adrenergic
blockade, and subject age on insulin-mediated changes in plasma potassium.
In 16 young subjects, 2-h insulin infusions at 20 (n = 6), 80 (n = 13), and
200 (n = 8) mU.m-2.min-1 resulted in dose-dependent declines in plasma
potassium (P less than 0.001 at all doses) during the 1st h. During the 2nd
h plasma potassium declined during the 20 mU.m-2.m-1 infusions, was stable
during the 80 mU.m-2.m-1 infusions, and rose slightly during the 200
mU.m-2.min-1 infusions. There was a significant reciprocal relationship
between the changes in plasma potassium during the 1st and 2nd h of study
(r = 0.99, P less than 0.01). During 4-h infusions (80 mU.m-2.min-1, n = 6)
plasma potassium declined during the first 90 min (p less than 0.001) and
rose thereafter until the end of the infusion (P less than 0.05). Studies
with and without propranolol infusion at two insulin dose levels (20 and 80
mU.m-2.min-1) in six young subjects showed no effect of beta-blockade, and
studies at three insulin dose levels [20 (n = 5), 80 (n = 6), and 200 (n =
6) mU.m-2.min-1 in 10 older males (63-77 yr] showed no effect of age on the
changes in plasma potassium during hyperinsulinemia. These results suggest
the presence of a regulatory mechanism influencing insulin-mediated
alterations in plasma potassium. This mechanism appears uninfluenced by age
or beta-adrenergic blockade.
