Journal of Applied Physiology, Vol 69, Issue 2 485-489, Copyright © 1990 by American Physiological Society
Beta-blockade with intrinsic sympathetic activity modifies favorably exercise-induced changes in plasma lipoproteins
P. Van Nguyen, J. Cleroux, M. Peterson and F. H. Leenen
Hypertension Unit, Toronto Western Hospital, Ontario, Canada.
The effects of beta-blockade on acute exercise-induced changes in plasma
lipoprotein levels were investigated in 12 healthy normotensive subjects by
use of beta-blockers of three types: a nonselective agent, a beta
1-selective agent, and a nonselective agent with intrinsic sympathomimetic
activity (ISA) or partial agonist activity. Each subject received each drug
and a placebo for 1 wk each according to a randomized double-blind
crossover design. After placebo, exercise caused 10-20% increases in total
plasma cholesterol and the high-density lipoprotein (HDL)-cholesterol
fraction. The total-to-HDL cholesterol ratio fell, particularly during the
30-min recovery phase. Pindolol treatment increased resting values of HDL
cholesterol (from 43 +/- 4 to 48 +/- 4 mg/dl) and potentiated the response
to exercise (to 59 +/- 5 vs. 51 +/- 4 mg/dl after placebo). The
total-to-HDL cholesterol ratio was significantly lower after pindolol
treatment than after placebo. In contrast, neither atenolol nor timolol
affected exercise-induced changes in plasma lipoprotein levels. The effects
of pindolol on other study parameters (exercise endurance and
exercise-induced increases in systolic blood pressure, heart rate, and
potassium) were similar to the effects of the nonselective agent, timolol.
We conclude that the effects of pindolol on the plasma lipid profile are
due to its ISA and that the process activated (possibly plasma
lecithin-cholesterol acyltransferase activity) is under minimal sympathetic
control and, therefore, sensitive to the expression of ISA both at rest and
in response to exercise.
