Stretch-activated single-channel and whole cell currents in vascular smooth muscle cells.
Mechanosensitive ion channels may play a key role in transducing vascular smooth muscle (VSM) stretch into active force development. To test this hypothesis, we recorded single-channel and macroscopic currents during mechanical stimulation of enzymatically dispersed vascular smooth muscle cells. Patch pipette suction activated a nonselective cation channel that was permeable to K+, Na+, and Ca2+. Whole cell stretch was accomplished using two patch-type micropipettes attached to the cell ends with suction. Stretch elicited a sustained depolarization with a magnitude similar to that observed in pressurized arteries. Under whole cell voltage clamp, stretch activated an inward current with a reversal potential near -15 mV. In another series of experiments, whole cell stretch failed to modify the current-voltage relationship for voltage-gated calcium currents. Thus, in VSM, both single-channel and whole cell data are consistent with activation of a nonselective cation channel by stretch. This mechanism may, in part, account for pressure-induced activation of intact blood vessels.
Davis
M J
MJ
Department of Medical Physiology, College of Medicine, Texas A&M University, College Station 77843.
Donovitz
J A
JA
Hood
J D
JD
D000818:Animals; D015220:Calcium Channels / Q000502:physiology; D002469:Cell Separation; D004594:Electrophysiology; D015640:Ion Channel Gating; D007473:Ion Channels / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000502:physiology*; D010812:Physical Stimulation; D014661:Vasoconstriction
D015220:Calcium Channels; D007473:Ion Channels