Fibrinolytic response during exercise and epinephrine infusion in the same subjects.
To determine whether exercise-induced increases in tissue plasminogen activator (t-PA) were related to plasma epinephrine concentration during exercise, 14 healthy men (aged 24 to 62 years) were studied during epinephrine infusions (10, 25 and 50 ng/kg per min) and graded supine bicycle exercise, beginning at 33 W and increasing in 33-W increments until exhaustion. Plasma epinephrine, active and total t-PA, active plasminogen activator inhibitor type 1 (PAI-1) and t-PA/PAI-1 complex concentrations were measured at each exercise and infusion level. During epinephrine infusion, active and total t-PA levels increased linearly with the plasma epinephrine concentration (respective slopes [+/- SEM] of 0.062 +/- 0.003 and 0.076 +/- 0.003 pmol/ng epinephrine). During exercise, t-PA levels did not increase until plasma epinephrine levels increased, after which both active and total t-PA levels again increased linearly with the plasma epinephrine concentration, but at twice the rate observed with epinephrine infusion (0.131 +/- 0.005 and 0.147 +/- 0.005 pmol/ng, respectively). The t-PA level in blood was directly proportional to the plasma epinephrine concentration during both exercise and epinephrine infusion, suggesting that epinephrine release during exercise stimulates t-PA secretion. In these healthy subjects, active plasminogen activator inhibitor type 1 and t-PA/PAI-1 complex levels were low (41 +/- 11 and 21 +/- 5 pmol/liter, respectively) and did not change significantly during exercise or epinephrine infusion. It is concluded that approximately 50% of the increase in t-PA during exercise is due to stimulated release of t-PA by epinephrine.(ABSTRACT TRUNCATED AT 250 WORDS)
Chandler
W L
WL
Department of Laboratory Medicine, University of Washington, Seattle 98195.
Veith
R C
RC
Fellingham
G W
GW
Levy
W C
WC
Schwartz
R S
RS
Cerqueira
M D
MD
Kahn
S E
SE
Larson
V G
VG
Cain
K C
KC
Beard
J C
JC
D000328:Adult; D004837:Epinephrine / Q000097:blood / Q000494:pharmacology*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005342:Fibrinolysis / Q000502:physiology*; D006801:Humans; D008297:Male; D015849:Plasminogen Inactivators / Q000097:blood; D010959:Tissue Plasminogen Activator / Q000097:blood*
D015849:Plasminogen Inactivators; D010959:Tissue Plasminogen Activator; D004837:Epinephrine