A mechanosensitive calcium channel in human intestinal smooth muscle cells.
OBJECTIVE
Gastrointestinal smooth muscle strips devoid of enteric nerve cells can contract in response to stretch, suggesting that mechanosensitivity and mechanotransduction can occur at the level of the smooth muscle cell. The aim of this study was to determine whether stretch-activated calcium channels are present in gastrointestinal smooth muscle cells.


METHODS
Whole-cell and single-channel calcium currents were measured from human jejunal circular smooth muscle cells in response to increased intracellular pressure, bath perfusion, and membrane stretch.


RESULTS
At 10 mm Hg positive pressure, peak calcium current increased from -36 +/- 10 pA to -53 +/- 13 pA. Bath perfusion at 10 mL/min increased calcium current from -97.7 +/- 14 pA to -122 +/- 16 pA. Single-channel open probability increased in response to negative pipette pressure. All increases were blocked by nifedipine.


CONCLUSIONS
A stretch-activated, nifedipine-sensitive calcium channel is present in human jejunal circular smooth muscle cells. The channel is activated by both an increase in intracellular pressure and by external shear forces. The presence of a stretch-activated calcium channel in gastrointestinal smooth muscle cells may allow the smooth muscle cells to act directly as mechanotransducers and to participate in the regulation of smooth muscle tone and intestinal motility.
Farrugia
G
G
Department of Physiology, Mayo Clinic, Rochester, Minnesota, USA. Farrugia.gianrico@mayo.edu
Holm
A N
AN
Rich
A
A
Sarr
M G
MG
Szurszewski
J H
JH
Rae
J L
JL
D015220:Calcium Channels / Q000502:physiology*; D004553:Electric Conductivity; D006801:Humans; D007424:Intracellular Fluid / Q000502:physiology; D007583:Jejunum / Q000166:cytology / Q000378:metabolism*; D008465:Mechanoreceptors / Q000502:physiology*; D009130:Muscle, Smooth / Q000166:cytology / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D010477:Perfusion; D011312:Pressure; D013314:Stress, Mechanical
D015220:Calcium Channels