P. Mantymaa et al., EFFECT OF ENDURANCE TRAINING ON ATRIAL-NATRIURETIC-PEPTIDE GENE-EXPRESSION IN NORMAL AND HYPERTROPHIED HEARTS, Journal of applied physiology, 76(3), 1994, pp. 1184-1194
We studied the effects of physical endurance training on atrial natriu
retic peptide (ANP) gene expression in beagle dogs, Wistar rats, and s
pontaneously hypertensive rats (SHR). The dogs underwent a gradually i
ncreased running training up to 40 km/day on a treadmill for 55 wk whi
le the nontrained sibling control dogs were kept in their cages throug
hout the study. Endurance training caused a significant 13% (P < 0.05)
increase in ventricular hypertrophy but did not change plasma immunor
eactive (ir)-ANP levels at rest or ventricular ANP mRNA or irANP level
s. When normotensive Wistar rats ran up to 2,200 m/day for 8 wk, no si
gnificant change was seen in ventricular hypertrophy or in plasma or v
entricular irANP levels at rest compared with nontrained controls. How
ever, endurance training caused a 2.2-fold increase in epicardial ANP
mRNA levels (P < 0.05). In the SHR strain, running training up to 900
m/day for 31 wk increased ventricular hypertrophy of trained SHR by 7%
(P < 0.01) and caused a concomitant 1.6- to 1.7-fold elevation in ven
tricular irANP and ANP mRNA levels (P < 0.01-0.001) compared with nont
rained SHR. In contrast, changes in atrial ANP mRNA or irANP levels in
response to training were small in all three protocols. This study sh
ows that in the normal heart induction of ANP synthesis by endurance t
raining is not associated with ventricular hypertrophy. Moreover, the
common stimulus for ventricular ANP synthesis induced by both chronic
pressure overload and physical training may be mechanical stretching o
f cardiac myocytes, because endurance training further stimulated ANP
synthesis in hypertrophied ventricles in SHR.