Exercise Linked to Transient Increase in Expression and Activity of Cation Channels in Newly Formed Hind-limb Collaterals

ObjectiveThis study aimed to compare arteriogenesis after femoral artery occlusion as influenced by exercise or arteriovenous shunt and follow changes in collateral transient receptor potential cation channel, subfamily V, member 4 (Trpv4).DesignA prospective, controlled study wherein rats were subjected to femoral artery ligation (FAL), or FAL + arteriovenous shunt. Collateral Trpv4 was determined 0.5 and 6 h post exercise.MethodsRats were subjected to exercise for 15 min, twice daily. The number and diameter of collaterals were assessed after 7 days. Collateral Trpv4 expression was quantified by reverse transcription-polymerase chain reaction.ResultsCollateral number and diameter per limb were significantly higher in the shunt group (number: 16.0 ± 2.4 and diameter: 216.0 ± 34 μm) compared to the ligature (number: 9.4 ± 2 and diameter: 144 ± 21 μm) and exercise groups (number: 9.9 ± 2.5 and diameter: 151 ± 15 μm). Trpv4 expression in collaterals harvested 0.5 h post exercise was not significantly different from expression in shunted rats. It was significantly lower in collaterals harvested 6 h post exercise (comparable to that in ligated rats).ConclusionCollateral formation was greater in the shunt group than in the exercise group. Exercise-induced Trpv4 up-regulation, not significantly different from that achieved with shunt, returned to control values when evaluated 6 h post exercise. More frequent exercise to chronically increase fluid shear stress, as with a shunt model, may be required for sufficient arteriogenesis to compensate for peripheral occlusion.