The response to exercise stress is characterized by an increase in circulat
ing catecholamines and rapid synthesis of the inducible member of the 70 kD
a family of heat shock proteins (Hsp70). Cell culture studies indicate that
Hsp70 expression is influenced by beta-adrenergic receptor intermediates i
ncluding cyclic AMP (cAMP) and cAMP dependent protein kinase (PKA). Thus, i
n the present investigation, the effect of a beta-adrenergic agonist, isopr
oterenol (ISO; 10 mg/kg) and a beta-adrenergic antagonist, nadolol (NAD; 25
mg/kg), on the in vivo expression of Hsp70 in rodent cardiac and skeletal
muscle following moderate (MOD; 17 m/min) and exhaustive (EXH; 30 m/min) ex
ercise was examined. While ISO alone did not induce Hsp70 synthesis, ISO tr
eatment potentiated Hsp70 expression following MOD in the white vastus and
heart (395 +/- 29 and 483 +/- 29% greater than control respectively, P < 0.
05). Furthermore, this effect was reversed with combined beta-adrenergic ag
onist and antagonist treatment (ISO+NAD) indicating that the isoproterenol
induced increase in post-exercise Hsp70 expression was mediated via beta-ad
renergic receptor activity. However, there were no differences in Hsp70 lev
els among treatment groups following EXH. The failure of NAD to attenuate H
sp70 accumulation following EXH suggests that beta-adrenergic receptor acti
vity is not the main signal in the induction of Hsp70 following exercise. H
sp70 induction was dependent on exercise intensity and ISO administration p
rior to MOD resulted in Hsp70 levels similar to those observed following EX
H. The results from the present investigation indicate that beta-adrenergic
receptor stimulation does not induce Hsp70 synthesis per se, but may be on
e factor involved in the complex regulation of the stress response to exerc
ise in vivo.