Fatigability and Blood Flow in the Rat Gastrocnemius-Plantaris-Soleus after Hindlimb Suspension

Document Type

Article

Language

eng

Format of Original

6 p.

Publication Date

9-1992

Publisher

American Physiological Society

Source Publication

Journal of Applied Physiology

Source ISSN

0021-8987

Original Item ID

DOI: 10.1152/jappl.1992.73.3.1135

Abstract

The purpose of this study was to test the hypothesis that hindlimb suspension increases the fatigability of the soleus during intense contractile activity and determine whether the increased fatigue is associated with a reduced muscle blood flow. Cage-control (C) and 15-day hindlimb-suspended (HS) rats were anesthetized, and either the gastrocnemius-plantaris-soleus (G-P-S) muscle group or the soleus was stimulated (100 Hz, 100-ms trains at 120/min) for 10 min in situ. In the G-P-S preparation, blood flow was measured with radiolabeled microspheres before and at 2 and 10 min of contractile activity. The G-P-S fatigued markedly at this stimulation frequency, and the differences between C and HS animals were not significant until the 9th min of contractile activity. In contrast, the stimulation resulted in faster rates and significantly larger amounts of fatigue in the soleus from HS than from C animals. The atrophied soleus showed significant differences by 1 min of stimulation (C = 70 ± 1% vs. HS = 57± 2% of peak train force) and remained different at 10 min (C = 64 ± 4% vs. HS = 45 ± 2% peak train force). Relative blood flow to the soleus was similar between groups before and during contractile activity (rest: C = 20 ± 3 vs. HS = 12 ± 3; 2 min: C = 128 ± 6 vs. HS = 118 ± 4; 10 min: C = 123 ± 11 vs. HS = 105 ± 11 ml.min-1.100 g-1). In conclusion, these results established that 15 days of HS increased the fatigability of the soleus, but the effect was not caused by a reduced muscle blood flow.

Comments

Journal of Applied Physiology, Vol. 73, No. 3 (September 1992): 1135-1140. DOI.

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