Water uptake in stimulated cat skeletal muscle

Abstract

Isolated vasodilated cat hindlimb skeletal muscles were perfused at constant flow and stimulated at 4 Hz for 2-4 min in three studies. Water uptake rates were measured gravimetrically or calculated from venous protein concentration changes. Venous plasma sodium, potassium, chloride, and osmolality were also measured. Maximum water uptake rates averaged 1.8 +/- 0.2 (SE) ml.min-1 x 100 g-1, reaching twice that in some experiments. Water uptake continued after stimulation had ceased. Constant-flow perfusion maintained a constant capillary pressure that was corroborated by measurements of arterial and venous perfusate pressures. Water uptake rate was not influenced by hematocrit but was highly correlated with plasma flow rate. The evidence strongly suggests that small-molecule osmotic pressure was the primary pressure causing the transcapillary water flux. Venous plasma sodium and chloride concentrations increased almost as much as protein (108 and 87% of the protein increase, respectively), as would be expected when water fluxes are driven by small-molecule osmotic pressure. Peak potassium efflux averaged 36 +/- 3 mu eq.min-1 x 100 g-1, but potassium did not contribute significantly to the osmotic gradient.

Skeletal Muscle Fatigue: Cellular Mechanisms

“…Muscle cells may take up water and swell during fatiguing exercise (403,458). Muscle fiber swelling increases tetanic force production and maximum shortening velocity (151) and hence counteracts the opposite changes that occur in fatigue.…”

The use of magnetic resonance imaging to evaluate the effects of cooling on skeletal muscle after strenuous exercise

“…Fotedar et al (1990) suggested that an acute increase in blood flow would be associated with a large increase in intramuscular water. Similarly, Watson et al (1993) reported that the higher plasma flow rate tended to increase transcapillary water flux and tissue water uptake. Secondly, exercise-induced metabolite accumulation should also contribute to the fluid exchange into the interstitium (Fleckenstein et al 1991;Watson et al 1993).…”

“…Similarly, Watson et al (1993) reported that the higher plasma flow rate tended to increase transcapillary water flux and tissue water uptake. Secondly, exercise-induced metabolite accumulation should also contribute to the fluid exchange into the interstitium (Fleckenstein et al 1991;Watson et al 1993). Fleckenstein et al (1991) demonstrated that patients with McArdle's disease, where glycogenolysis and lactic acid production are blocked due to myophosphorylase deficiency, showed no elevations in T2 and SI on T2-weighted image in affected muscles immediately after exercise.…”

“…Knight (1976) suggested that cooling causes the blood flow reduction and vasoconstriction in affected areas and should lead to less fluid accumulation. Furthermore, a low flow rate appears to reduce the tissue water uptake (Watson et al 1993). On the other hand, an increased muscle temperature and/or blood flow due to exercise has been suggested to be associated with T2 elevation (Prior et al 2001;Takahashi et al 1994).…”

System for measuring isolated rat soleus muscle belly response to tetanic stimulation

“…A device for measuring the muscle belly displacement for isolated skeletal muscle was not available. The measurements of the muscle force and the muscle belly displacement [2] indirectly indicate the rate of osmotic flow of water into the muscle cell during a tetanic contraction. During the muscle activity the concentrations of phosphate [3] lactate [3], and sodium -hydrogen exchanger, which regulate intracellular pH [4] increase and directly produce changes in intracellular mounted for longitudinal and transversal displacement measurements.…”