Prolonged force increase following a high-frequency burst is not due to a sustained elevation of [Ca2+]i.
Am J Physiol Cell Physiol
; 283(1): C42-7, 2002 Jul.
Article
en En
| MEDLINE
| ID: mdl-12055071
A brief high-frequency burst of action potentials results in a sustained force increase in skeletal muscle. The present study investigates whether this force potentiation is the result of a sustained increase of the free myoplasmic [Ca2+] ([Ca2+]i). Single fibers from mouse flexor brevis muscles were stimulated with three impulses at 150 Hz (triplet) at the start of a 350-ms tetanus or in the middle of a 700-ms tetanus; the stimulation frequency of the rest of the tetanus ranged from 20 to 60 Hz. After the triplet, force was significantly (P < 0.05) increased between 17 and 20% when the triplet was given at the start of the tetanus and between 5 and 18% when the triplet was given in the middle (n = 7). However, during this potentiation, [Ca2+]i was not consistently increased. Hence, the increased force following a high-frequency burst is likely due to changes in the myofibrillar properties.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Calcio
/
Músculo Esquelético
/
Membranas Intracelulares
Límite:
Animals
Idioma:
En
Revista:
Am J Physiol Cell Physiol
Asunto de la revista:
FISIOLOGIA
Año:
2002
Tipo del documento:
Article
País de afiliación:
Países Bajos
Pais de publicación:
Estados Unidos