Changes in enteric neural regulation of smooth muscle in a rabbit model of small intestinal inflammation.
In vitro electrophysiological studies of ileal circular muscle from rabbits with ricin-induced inflammation were performed to investigate whether altered neural control or myogenic activity contributes to previously described changes in in vivo myoelectric activity. Ricin treatment increased mean slow-wave amplitude but not frequency or resting membrane potential. Prolonged electrical field stimulation evoked a hyperpolarization during the stimulus train and a depolarization on cessation of stimulation. In the presence of atropine, the depolarization was larger in ricin-treated tissue than in control tissue, showing that ileitis enhanced noncholinergic excitation. The nitric oxide synthase inhibitor N-nitro-L-arginine methyl ester reduced the hyperpolarization in ricin-treated but not in control tissue, suggesting that inflammation increased nitric oxide-mediated inhibition. Substance P desensitization reduced noncholinergic excitation and mean slow-wave amplitude only in ricin-treated tissue, demonstrating that changes in these parameters during inflammation resulted from increased release of, or sensitivity to, tachykinins. These data suggest that acute ileitis alters tachykinin- and nitric oxide-mediated neurotransmission that may affect the normal pattern of ileal motility and/or sensory reflexes.
Goldhill
J M
JM
Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799, USA.
Sanders
K M
KM
Sjogren
R
R
Shea-Donohue
T
T
D000818:Animals; D004558:Electric Stimulation; D004594:Electrophysiology; D017615:Enteric Nervous System / Q000503:physiopathology; D007079:Ileitis / Q000139:chemically induced / Q000503:physiopathology*; D007082:Ileum / Q000294:innervation*; D008297:Male; D009130:Muscle, Smooth / Q000503:physiopathology*; D009433:Neural Inhibition; D009569:Nitric Oxide / Q000378:metabolism; D010275:Parasympathetic Nervous System / Q000503:physiopathology; D011817:Rabbits; D012276:Ricin; D015320:Tachykinins / Q000502:physiology; D013997:Time Factors
D015320:Tachykinins; D009569:Nitric Oxide; D012276:Ricin