TY - JOUR
T1 - Effect of chronic resistive loading on inspiratory muscles in rats
AU - Tarasiuk, A.
AU - Scharf, S. M.
AU - Miller, M. J.
PY - 1991/1/1
Y1 - 1991/1/1
N2 - The development of animal models of respiratory muscle training would be useful in studying the physiological effects of training. Hence, we studied the effects of chronic resistive loading (CRL) for 5 wk on mass, composition,and mechanics of inspiratory muscles in laboratory rats. CRL was produced by means of a tracheal cannula (loaded animals) and results were compared with sham-operated controls. Acutely, upper airway obstruction led to a doubling of inspiratory pleural pressure excursion and 25% decrease in respiratory rate. We observed no changes in lung pressure-volume curves, nor in the geometry of the respiratory system in loaded compared with control animals. Muscle mass normalized for body mass increased in the diaphragm (DI) and the wet weight-to-dry weight ratio increased in the sternomastoid (SM) in loaded compared with control animals. Loaded animals demonstrated a decrease in ether extractable (fat) content of the DI and SM muscles but not the gastrocnemius. For the DI there was no change in length at which active tension was maximal (L(o)), but there was an increase in maximum tension at lengths close to L(o) in loaded compared with control rats. Endurance did not change, although twitch tensions remained higher in loaded compared with control rats. We conclude that 1) alteration of inspiratory muscle structure and function occurs in rats with CRL; 2) the DI and SM demonstrate different adaptive responses to CBL; and 3) although maximum tension increases, endurance does not.
AB - The development of animal models of respiratory muscle training would be useful in studying the physiological effects of training. Hence, we studied the effects of chronic resistive loading (CRL) for 5 wk on mass, composition,and mechanics of inspiratory muscles in laboratory rats. CRL was produced by means of a tracheal cannula (loaded animals) and results were compared with sham-operated controls. Acutely, upper airway obstruction led to a doubling of inspiratory pleural pressure excursion and 25% decrease in respiratory rate. We observed no changes in lung pressure-volume curves, nor in the geometry of the respiratory system in loaded compared with control animals. Muscle mass normalized for body mass increased in the diaphragm (DI) and the wet weight-to-dry weight ratio increased in the sternomastoid (SM) in loaded compared with control animals. Loaded animals demonstrated a decrease in ether extractable (fat) content of the DI and SM muscles but not the gastrocnemius. For the DI there was no change in length at which active tension was maximal (L(o)), but there was an increase in maximum tension at lengths close to L(o) in loaded compared with control rats. Endurance did not change, although twitch tensions remained higher in loaded compared with control rats. We conclude that 1) alteration of inspiratory muscle structure and function occurs in rats with CRL; 2) the DI and SM demonstrate different adaptive responses to CBL; and 3) although maximum tension increases, endurance does not.
UR - http://www.scopus.com/inward/record.url?scp=0026056915&partnerID=8YFLogxK
U2 - 10.1152/jappl.1991.70.1.216
DO - 10.1152/jappl.1991.70.1.216
M3 - Article
AN - SCOPUS:0026056915
SN - 0161-7567
VL - 70
SP - 216
EP - 222
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
IS - 1
ER -