Muscle fatigue in the frog semitendinosus: role of the high-energy phosphates and Pi. Am J Physiol 1992 Oct;263(4 Pt 1):C803-9
Date
10/01/1992Pubmed ID
1415669DOI
10.1152/ajpcell.1992.263.4.C803Scopus ID
2-s2.0-0026808380 (requires institutional sign-in at Scopus site) 29 CitationsAbstract
The purpose of this study was to determine the concentration of ATP, phosphocreatine (PC), Pi, lactate, and glycogen in single frog skeletal muscle fibers and assess their role in the etiology of muscle fatigue. The frog semitendinosus (ST) muscle was fatigued, quick frozen at selected time points of recovery, and freeze-dried, and single fibers were dissected, weighed, and assayed for ATP, PC, lactate, Pi, and glycogen. The fatigue protocol reduced peak tetanic force (Po) to 8.5% of initial, while ATP and PC decreased from 45.18 to 33.16 and 128.90 to 28.76 mmol/kg dry wt, respectively. Lactate and Pi increased from 29.36 to 100.84 and 33.04 to 142.50 mmol/kg dry wt, respectively. It is doubtful that the small decline in ATP limited cross-bridge force production. Although a significant correlation between the recovery of PC and Po was demonstrated (r = 0.994), the time period showing the fastest rate of force recovery coincided with little change in PC. A significant correlation was demonstrated between the recovery of both total and the H2PO4- form of Pi and Po. In conclusion, the results of this study are incompatible with the hypothesis that the high-energy phosphates (ATP and PC) mediate muscle fatigue. The large increase in Pi with stimulation and the high correlation between the recovery of both total and the H2PO4- form of Pi and Po support a role for Pi in the production of skeletal muscle fatigue.
Author List
Thompson LV, Fitts RHAuthor
Robert Fitts PhD Professor in the Biological Sciences department at Marquette UniversityMESH terms used to index this publication - Major topics in bold
Adenosine TriphosphateAnimals
Hindlimb
Isometric Contraction
Muscle Contraction
Muscles
Phosphocreatine
Phosphorus
Rana pipiens
