Assessment of gait dynamics in rats submitted to limb ischemia

Drag-reducing polymers increase exercise tolerance in an ischemic hind-limb rat model

OBJECTIVE

Drag-reducing polymers are long-chain, blood soluble macromolecules that can improve microcirculation in vivo. This study aimed to examine the effects of drag-reducing polymers on exercise tolerance in a rat model of hind-limb ischemia.

METHODS

After adaptive running training, bilateral femoral artery ligation models were established in 64 Wistar rats. During an exhaustive exercise, polyethylene oxide or normal saline was intravenously injected to each group (n = 32) at 4 mL/h for 10 min. The exhaustive exercise time was recorded, and lactic acid levels in gastrocnemius muscle and serum were measured. Serum levels of nitric oxide, creatine kinase and lactate dehydrogenase were measured as biomarkers of physical fatigue.

RESULTS

Compared with saline-treated control group, rats in polyethylene oxide-treated group had longer exhaustive exercise time (774.7 ± 171.5 s vs. 687.6 ± 166.1 s, p = 0.043), and lower lactic acid level in gastrocnemius muscle (p < 0.01) but no significant difference in serum lactic acid level between two groups was observed (p > 0.05). Nitric oxide level was higher in polyethylene oxide group than in controls (p < 0.05), but no significant differences in serum creatine kinase and lactate dehydrogenase levels between two groups were observed (p > 0.05).

CONCLUSION

Drag-reducing polymers contribute to the enhancement of exercise endurance and exert anti-fatigue effect.

Effect of cilostazol and pentoxifylline on gait biomechanics in rats with ischemic left hindlimb

OBJECTIVE

The purpose of this study was to determine the impact of pharmacologic treatment with cilostazol and pentoxifylline on gait biomechanics of ischemic rat hindlimbs compared with nonischemic controls.

METHODS

An experimental study was designed using 30 Wistar rats divided into five groups (n = 6): control (C); ischemia (I) - animals submitted to left common iliac artery interruption without pharmacologic treatment; pentoxifylline (Pen) - rats submitted to procedure and treated with pentoxifylline 3 mg/kg twice a day for 6 weeks; cilostazol (Cil) - animals submitted to procedure and treated with cilostazol 30 mg/kg twice a day for 6 weeks; and sham (S) - animals submitted to procedure without artery interruption. Gait analysis was performed using a computed treadmill. Time, number, and duration of each hindlimb contact were obtained. The total number of contacts (TNC) and the total duration of contacts (TDC) were compared between left and right hindlimb and among groups. Left hindlimb ischemic incapacitation index (LHII) was defined by the formula: LHII = (1-TNCleft x TDCleft / TNCright x TDCright) x 100.

RESULTS

Left hindlimb TNC values were twofold lower in I, Pen, and Cil groups than in C and S groups (P < .01). In I, Pen, and Cil groups, TNC values for the left hindlimb were half of the right hindlimb ones (P < .01). Left hindlimb TDC values were lower in I and Pen groups than the other groups (P < .01). Cil group presented twofold increased values, not different from C and S groups (P = 0.16). Right hindlimb TNC values were greater for I group (P < .01). LHII was around zero in C and S groups and 82 in both I and Pen groups (P < .01). Cil group presented a LHII of 42; higher than C and S groups, but lower than I and Pen groups (P < .01).

CONCLUSIONS

Cilostazol at a dose of 30 mg/kg twice a day promoted improvement in gait performance in rats submitted to chronic hindlimb ischemia. Pentoxifylline at a dose of 3 mg/kg twice a day did not show this effect.