Faculty Collaboration Database

Muscle fatigue in frog semitendinosus: role of intracellular pH. Am J Physiol 1992 Jun;262(6 Pt 1):C1507-12

Date

06/01/1992

Pubmed ID

1616012

DOI

10.1152/ajpcell.1992.262.6.C1507

Scopus ID

2-s2.0-0026703741 (requires institutional sign-in at Scopus site)   20 Citations

Abstract

The purpose of this study was to utilize glass microelectrodes to characterize the intracellular pH (pHi) before and during recovery from fatigue in the frog semitendinosus (ST) muscle. A second objective was to evaluate the relationship between pHi and contractile function. The frog ST muscle (22 degrees C) was fatigued by direct electrical stimulation with 100-ms 150-Hz trains at 1/s for 5 min. Peak tetanic force (Po) was reduced to 8.5% of initial force and recovered in a biphasic manner, returning to the resting value by 40 min. Resting pHi was 7.00 +/- 0.02 (n = 37) and declined with fatigue to an average value of 6.42 at 3 min of recovery. During recovery pHi significantly increased and by 25 min had returned to the prefatigue value. The pHi recovery was highly correlated to the slow phase of Po recovery (r = 0.98, P less than 0.001). The mean resting membrane potential was -78 +/- 1.0 mV (n = 42) and at 3 min of recovery was depolarized to -67 +/- 4 mV. Both the peak rate of twitch force development (+dP/dt) (r = 0.99, P less than 0.001) and decline (-dP/dt) (r = 0.94, P less than 0.014) were highly correlated to pHi during the slow phase of recovery. Contraction time (CT) and one-half relaxation time (1/2RT) increased significantly and recovered exponentially. The recovery of CT and 1/2RT were both significantly correlated to pHi (r = -0.93, P less than 0.001 and r = -0.86, P less than 0.001 for CT and 1/2RT, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Author List

Thompson LV, Balog EM, Fitts RH

Author

Robert Fitts PhD Professor in the Biological Sciences department at Marquette University

MESH terms used to index this publication - Major topics in bold

Adenosine Triphosphate
Animals
Electric Stimulation
Hydrogen-Ion Concentration
In Vitro Techniques
Kinetics
Membrane Potentials
Microelectrodes
Muscle Contraction
Muscle Relaxation
Muscles
Rana pipiens
Time Factors