Role of potassium channels in rabbit intestinal motility disorders induced by 2, 2'-azobis (2-amidinopropane) dihydrochloride (AAPH).
Oxidative stress appears to play a role in the pathogenesis of several inflammatory gastrointestinal diseases. Changes in intestinal motility have been reported in different models of intestinal inflammation. The initiating factor of altered motility could be an alteration of gut redox status. The aim of this study was to investigate the effect of oxidative stress evoked by 2, 2'-azobis (2-amidinopropane) dihydrochloride (AAPH) on the intestinal motility of rabbit duodenum and the possible contribution of different K(+) channels in mediating this response. Whole thickness segments of rabbit duodenum were suspended in the direction of the longitudinal or circular smooth muscle fibres in an organ bath to study the effects of AAPH alone, or in the presence of different K(+) channel blockers on the amplitude, frequency and tone of spontaneous contractions. In circular muscle, AAPH 20 mM induced a reduction of the amplitude, the frequency and tone of the spontaneous contractions. In longitudinal muscle, AAPH 10 mM induced a reduction of the amplitude and tone of the spontaneous contractions. The reduction of the amplitude and tone induced by AAPH was reverted by BaCl2 (1 mM) and TEA (5 mM). Charybdotoxin (100 nM) and iberiotoxin (100 nM) only reverted the reduction of the tone induced by AAPH. In conclusion, our results show that the peroxyl radicals released by AAPH reduced the amplitude and the tone of the spontaneous contractions of the longitudinal smooth muscle from rabbit small intestine. Inward rectifier and intermediate and large-conductance Ca(2+)-activated K(+) channels could be involved in these effects.
Hernandez
L
L
Departamento de Farmacologia y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain.
Grasa
L
L
Fagundes
D S
DS
Gonzalo
S
S
Arruebo
M P
MP
Plaza
M A
MA
Murillo
M D
MD
D000578:Amidines / Q000494:pharmacology*; D000818:Animals; D005769:Gastrointestinal Motility / Q000187:drug effects; D066298:In Vitro Techniques; D007410:Intestinal Diseases / Q000139:chemically induced / Q000378:metabolism*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D018384:Oxidative Stress; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000378:metabolism*; D011817:Rabbits
D000578:Amidines; D026902:Potassium Channel Blockers; D015221:Potassium Channels; C046728:2,2'-azobis(2-amidinopropane)