Mechanosensitive potassium channels in rat colon sensory neurons.
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 Ca(2+)-free conditions. Gadolinium (Gd(3+)), 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.
Department of Pharmacology, College of Medicine, University of Iowa, Iowa City 52242, Iowa. xin-su@uiowa.edu
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D015761:4-Aminopyridine / Q000494:pharmacology; D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D003078:Colchicine / Q000494:pharmacology; D003106:Colon / Q000294:innervation*; D015638:Cytochalasin D / Q000494:pharmacology; D003599:Cytoskeleton / Q000187:drug effects / Q000502:physiology; D004232:Diuretics / Q000494:pharmacology; D005682:Gadolinium / Q000494:pharmacology; D005727:Ganglia, Spinal / Q000166:cytology / Q000502:physiology; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009475:Neurons, Afferent / Q000737:chemistry* / Q000502:physiology*; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D010812:Physical Stimulation; D011188:Potassium / Q000493:pharmacokinetics; D015221:Potassium Channels / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000493:pharmacokinetics; D013314:Stress, Mechanical; D013396:Suction; D019789:Tetraethylammonium / Q000494:pharmacology
D004232:Diuretics; D019384:Nucleic Acid Synthesis Inhibitors; D015221:Potassium Channels; C013407:benzamil; D015638:Cytochalasin D; D019789:Tetraethylammonium; D000584:Amiloride; D012964:Sodium; D005682:Gadolinium; D015761:4-Aminopyridine; D011188:Potassium; D003078:Colchicine; D002118:Calcium