Saiphon Kongkum. Underlying mechanisms of the alteration of respiratory structure and function after exhaustive exercise . Master's Degree(Exercise Physiology). Mahidol University. : Mahidol University, 2004.
Underlying mechanisms of the alteration of respiratory structure and function after exhaustive exercise
Abstract:
The purposes of this study were to investigate the mechanisms underlying the
alterations in structure and function of the respiratory system resulting from
exhaustive exercise. Male Sprague-Dawley rats, aged 8-10 wks, were used as animal
model, and randomly divided into two groups: control and exercised group. Acute
exhaustive exercise was performed by running on a treadmill at a speed of 27 m/min
untill exhaustion occured. Static pressure-volume relationships were determined by 1-
ml stepwise inflation, commencing from functional residual capacity, and recorded by
Biopac system. Coefficients, obtained from curve-fitting (Tablecurve) software were
used to calculate compliance and elastic work of breathing (WOB), at 5 ml intervals,
using specific software. Histological findings were performed under light microscope.
Results showed that pressure was increased as volume increased from 1 to 15 ml
(0.8225 to 7.4998 kPa) in the control group, which was not significantly different to
the exercised group (0.7541 to 6.9465 kpa). The overall characteristics of the static PV
relationship of the total respiratory system showed the sigmoid-like pattern (Scurve)
in both groups with non-significant static compliance of the lung (Cst(l)) at low,
middle, and highest lung volumes of both groups. When ribs were opened, the similar
non-significant changes were also observed. Thus, there was no significant difference
in Cst(l) between the groups either in the intact or open chest condition. Changes of
WOB in both groups were shown in similar, non-significant, pattern, increasing from
low to highest lung volumes. The histological study showed that exhaustive exercise
likely diminished size of alveoli with thicker alveolar wall with remarkable
appearance of polymorphonuclear (PMN) cell invasion. Results suggest that a single
bout of exhaustive exercise fails to induce changes in static respiratory mechanics in
rats whereas it could possibly induce thickening of interalveolar septum