The influence of different inspired air conditions on exercise-induced
bronchoconstruction (EIB) is well appreciated. However, the mechanism
by which this influence is exerted is uncertain. To determine if Vari
ed inspired air conditions during exercise could affect the catecholam
ine response to physical exercise, we had 13 asthmatic and 6 healthy c
hildren (aged 10-18 years) undergo two bouts of cycle ergometry tests
under different air conditions. One test was done while breathing cold
dry (CD) air(temperature, -20.2 degrees C; relative humidity, 0%) and
the other while breathing warm humid (WH) air (temperature, 34.3 degr
ees C; relative humidity, 100%). Forced expiratory volume in 1 second
(FEV(1)) and plasma catecholamine concentrations were recorded before
and after exercise. Marked EIB (48 +/- 5% SEM fail in FEV(1) from base
line) developed in all asthmatics after the CD exercise, but no EIB wa
s noted after the WH exercise. Normal controls had no EIB under either
test conditions. Plasma levels of catecholamines at rest, and the cha
nges that occurred during and after exercise, were comparable within a
s well as between the groups in both tests. Catecholamines did not ris
e in asthmatics following development of EIB. These data demonstrate t
hat inspired air conditions do not influence the sympathoadrenal respo
nse to exercise, at least as reflected in plasma catecholamine levels.
In fact, this response did not differ between asthmatics and normals,
irrespective of the development of EIB. These results are consistent
with previous reports about impaired catecholamine response of asthmat
ics to bronchoconstriction.