Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCA309

Poster Communications

Impaired myogenic tone of skeletal artery feeding atrophic hindlimb and its recovery by exercise training: associated changes in the ion channel currents of the arterial myocytes

M. YIN1, J. WOO1, S. KIM1

1. Department of Physiology, Department of Biomedical Sciences, seoul national university, Seoul, Korea (the Republic of).

Altered hemodynamic stimuli to skeletal arteries (SkA) are expected in the atrophic limbs. Here we investigate changes in the myogenic tone (MT) of SkA and the ionic currents of the SkA myocytes. In the rats (Sprague-Dawley rats, 8 weeks old, male) with unilateral sciatic denervation for 5 weeks (Den-5w), video-analysis of pressurized artery revealed impaired MT in the atrophy-side deep femoral arteries (DFAAtr) while intact MT in the contralateral side (DFACL). To get tissue samples, the rats were anesthetized with injection of sodium pentobarbital (60 mg/kg) and were immediately killed by decapitation after confirming a fully anaesthetized state. Whole-cell patch clamp showed that both voltage-operated L-type Ca2+ current (ICa,L) and TRPC-like current induced by intracellular GTPγS (IGTPγS) are lower in the DFAAtr myocytes than DFACL of Den-5w. Despite the unilateral hindlimb paralysis, the rats could perform treadmill exercise with the intact legs (20 m/min, 30 min, 3 times/wk). In Den-5w, when combined with 4 weeks of the ET exercise training (Den/ET-5w), both the loss of MT and the decay of IGTPγS were prevented while not the decay of ICa,L. The comparison of K+ channel currents between DFAAtr and DFACL myocytes showed complex tendencies. Voltage-gated K+ current (IKv) became higher in DFACL than DFAAtr, and the difference was abolished in Den/ET-5w. In contrast, the inwardly rectifying K+ current (IKir) and paxilline-sensitive Ca2+-activated K+ channel current (IBKCa) were not significantly different between DFACL and DFAAtr. The recovery of MT and the ionic currents in Den/ET-5w suggest beneficial effects of systemic endurance exercise on vascular physiology in motor nerve injury patients with atrophic skeletal muscles.

Where applicable, experiments conform with Society ethical requirements