Ap. Harrison et Ja. Flatman, Measurement of force and both surface and deep M wave properties in isolated rat soleus muscles, AM J P-REG, 277(6), 1999, pp. R1646-R1653
Citations number
38
Categorie Soggetti
Physiology
Journal title
AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY
In isolated soleus muscles of 4-wk-old rats, M wave parameters were recorde
d with surface and deep recording electrodes and examined in relation to bo
th twitch and tetanic force. Addition of ouabain (10(-5) M for 16 min) to i
solated muscles caused an similar to 40% decrease in twitch amplitude and a
rea (P < 0.01) that was associated with a 98% decrease in surface M wave am
plitude, a 78% decrease in deep M wave amplitude (both P < 0.001), a 98% de
crease in surface M wave area (P < 0.01), 48% of which occurred within 60 s
of addition of ouabain (P < 0.05), and a 55% decrease in deep M wave area
(P < 0.05). The decrease in twitch parameters on addition of ouabain was mo
st closely correlated with deep M wave area (r = 0.92). Direct tetanic stim
ulation at a frequency of 30 Hz resulted in an initial potentiation of M wa
ves, which was not seen at a frequency of 90 Hz. Instead, 90 Hz stimulation
resulted in a prompt decrease in tetanic force that was correlated with a
decrease in both deep M wave amplitude (r = 0.94; P < 0.01) and deep M wave
area (r = 0.96; P < 0.01). It is concluded that simultaneous surface and d
eep recordings involving area and amplitude are fundamental to analysis of
the effects of pharmacological agents on muscle performance and the use of
M waves as predictors of muscle excitability.