[Changes of potassium channel activity of hindlimb arterial smooth muscle cells in tail-suspended rats].
OBJECTIVE
To examine the change of potassium channel function in hindlimb arterial smooth muscle cells in tail-suspended rats and to elucidate the underlying electro-physiological mechanisms responsible for the depressed vascular responsiveness of hindlimb arteries induced by simulated weightlessness.


METHODS
The contractile responsiveness of femoral arterial rings of 1-wk and 4-wk tail-suspended rats to potassium channel blockers, tetraethylammonium chloride (TEA) and 4-aminopyridine (4-AP), were recorded, and the currents of large conductance calcium-dependent potassium channel (BK(Ca)) and voltage activated potassium channel (Kv) of vascular smooth muscle cells (VSMCs) in saphenous arteries from 1-wk tail-suspended rats were recorded using the whole cell recording mode of patch clamp technique.


RESULTS
The femoral arteries from of 1-wk and 4-wk tail-suspended rats showed a decreased contractile response to 60 mM KCl, and the ratio of their contractile responses induced by TEA or 4-AP to their responses induced by 60 mM KCl increased significantly after 1-wk and 4-wk simulated weightlessness. However no difference was found between 1-wk and 4-wk tail-suspended rats. The whole cell current recording showed that BK(Ca) current densities and K(v) current densities of VSMCs in saphenous artery increased significantly after 1-wk simulated weightlessness.


CONCLUSIONS
The contractile response of hindlimb arteries to KCl decreased after simulated weightlessness. The activities of BK(Ca) and K(v) of smooth muscle cells in hindlimb arteries from tail-suspended rats increased, and these changes might be among the electro-physiological mechanisms involved in the depressed vasoreactivity of hindlimb arteries due to simulated weightlessness.
Fu
Zhao-jun
ZJ
Cheng
Hong-wei
HW
Zhang
Li-fan
LF
Ma
Jin
J
Zhang
Le-ning
LN
Ma
Xiao-wu
XW
D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D005263:Femoral Artery / Q000187:drug effects / Q000502:physiology; D019417:Hindlimb Suspension; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects* / Q000502:physiology*; D024681:Potassium Channels, Calcium-Activated / Q000187:drug effects / Q000502:physiology; D024642:Potassium Channels, Voltage-Gated / Q000187:drug effects / Q000502:physiology; D011189:Potassium Chloride / Q000494:pharmacology*; D051381:Rats; D019789:Tetraethylammonium / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*; D018474:Weightlessness Simulation
D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D024642:Potassium Channels, Voltage-Gated; D019789:Tetraethylammonium; D011189:Potassium Chloride; D015761:4-Aminopyridine