The effect of pindolol on exercise-induced increase in plasma vasoactive prostanoids and catecholamines in healthy men

Abstract

The effect of intravenous pindolol (0.0256 mg/kg) on changes in plasma arachidonic acid (AA), some of its metabolites, and catecholamines induced by submaximal exercise was studied in six healthy male volunteers. Exercise resulted in markedly increased plasma concentrations of thromboxane B 2 (TxB 2) from 0.13±0.01 to 0.27±0.02 pmol/ml (mean±SEM; p<0.05) and AA from 4.1±0.6 to 8.0±0.9 μmol/1 (p<0.005). No significant changes were seen in plasma concentrations of 6-keto-PGF 1α or PGE 2 during exercise. A marked increase in plasma noradrenaline was seen already at 15 min of exercise, while the adrenaline concentration increased significantly at 30 min of exercise and a very marked increase in the adrenaline concentration was seen at exhaustion. A positive correlation (r=0.54; p<0.05) was seen between plasma TxB 2 and plasma adrenaline during exercise. The peak increase in both of these parameters was seen simultaneously at exhaustion. Pindolol treatment resulted in almost total inhibition of the increase in plasma TxB 2 and AA during exercise. Pindolol treatment also resulted in a significantly higher adrenaline level at exhaustion. These data seem to indicate that an increased sympathetic tone may result in an increased release of arachidonic acid and the formation of vasoconstrictive thromboxane A 2.