The Journal of Neurophysiology Vol. 84 No. 2 August 2000, pp. 836-843
Copyright ©2000 by the American Physiological Society

Mechanosensitive Potassium Channels in Rat Colon Sensory Neurons

 ¹Department of Pharmacology and  ²Department of Anesthesia, College of Medicine, University of Iowa, Iowa City 52242; and  ³Department of Veterans Affairs Medical Center, Iowa City, Iowa 52246

Su, X., R. E. Wachtel, and G. F. Gebhart. Mechanosensitive Potassium Channels in Rat Colon Sensory Neurons. J. Neurophysiol. 84: 836-843, 2000. Single-channel recording techniques were used to characterize mechanosensitive channels in identified (1.1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine methanesulfonate labeled) colon sensory neurons dissociated from adult S1 dorsal root ganglia. Channels were found in 30% (7/23) of patches in a cell-attached configuration and in 43% (48/111) of excised inside-out patches. Channels were highly selective for K⁺, had a slope conductance of 54 pS in symmetrical solutions, and were blocked by tetraethylammonium, amiloride, and benzamil. Channels were also seen under Ca²⁺-free conditions. Gadolinium (Gd³⁺), a known blocker of mechanosensitive ion channels, did not block channel activity. Tetrodotoxin and 4-aminopyridine were also ineffective. The cytoskeletal disrupters colchicine and cytochalasin D reduced the percentage of patches containing mechanosensitive channels. These results indicate that rat colon sensory neurons contain K⁺-selective mechanosensitive channels that may modulate the membrane excitability induced by colonic distension.