Neurogenic “Off” Contractions Are Mediated by NK2-Receptors in the Circular Muscle of Guinea Pig Ileum

Suzuki, Norihiro; Muramatsu, Ken; Gomi, Yasuo

doi:10.1254/jjp.64.213

Cited by 7 publications

(5 citation statements)

References 13 publications

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“…Within the mentioned limits, whatever current amplitude or pulse duration was used for stimulation, the induced circular contraction was of an ÔoffÕ type. Consistent with our results, ÔoffÕ contractions of intestinal muscles were reported by others, either when electrical stimulation was applied on muscle strips dissected from the colon of rats, 28,29 guinea pigs, 30,31 rabbits, 31 and humans, 32 or when stimulation of the intestine was performed in vivo. 10,11 During the electrically evoked contractions, the CSA decreased by similar magnitude when compared with spontaneous contraction, but eight times faster (Fig.…”

Section: Spontaneous Vs Electrically Induced Colon Contractions Effsupporting

confidence: 92%

Propulsive activity induced by sequential electrical stimulation in the descending colon of the pig

Sevcencu

Rijkhoff

Gregersen

et al. 2005

Neurogastroenterology Motil

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Section: Spontaneous Vs Electrically Induced Colon Contractions Effsupporting

confidence: 92%

Propulsive activity induced by sequential electrical stimulation in the descending colon of the pig

Sevcencu

Rijkhoff

Gregersen

et al. 2005

Neurogastroenterology Motil

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“…In these experiments, 10-' M CP-96,345 and 10-'M FK224 were used as an antagonist for NK1-receptors (15) and as a dual antagonist for NK1 and NK2-receptors (16,17), respectively. The effectiveness of these antagonists in blocking tachykinin receptors at the concentrations used was discussed previously (14). Figure 5 shows that 10-' M CP-96,345 slightly inhibit ed the SP-induced contractions in the presence of 10-6 M atropine, while it did not affect the contractions induced by the other two tachykinins.…”

Section: Effects Of Tetrodotoxin On Tachykinin-induced Contrac Tions mentioning

confidence: 66%

“…The methods to record contractions of the circular mus cle in segment preparations were described before (13,14). An aluminum tube holder, which had a small rectan gular window opened in the middle region, was put into the lumen of the ileal segment (2 to 3 cm), and the seg ment was fixed with thread covering the window to the holder.…”

Section: Measurement Of Contractions In Segment Preparationsmentioning

confidence: 99%

“…After equilibration for at least 60 min, trans mural stimulations by 100 electrical pulses (0.05-msec du ration, 50 V, 10 Hz) were applied to the segment prepara tion. These stimulations induced an "on" contraction and an "off" contraction (14), and the amplitude of the "on" contraction was used to quantitate agonist-induced con tractions.…”

Section: Measurement Of Contractions In Segment Preparationsmentioning

confidence: 99%

See 1 more Smart Citation

Tachykinin-Induced Contractions in the Circular Muscle of Guinea Pig Ileum.

Suzuki¹,

Muramatsu²,

Gomi³

1994

Jpn.J.Pharmacol

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ABSTRACT-Actions of substance P (SP, 10-9 to 10-6 M), neurokinin A (NKA, 10-9 to 10-6 M) and neurokinin B (NKB, 10-10 to 10-6 M) in the circular muscle of guinea pig ileum were investigated in segment and strip preparations, in which methacholine produced similar contractions. In the segment preparations, three tachykinins produced repeatedly occurring twitch-like contractions. Their efficacies were similar with the same maximal contractions, but their potencies were different (NKB > NKA = SP). Latency (38 sec) was observed before the initiation of contractions in response to NKA, but not to SP or NKB. Atropine (10-6 M) and tetrodotoxin (3 x 10-'M) did not affect NKA-induced contractions, but inhibited SP and NKB induced contractions; the dose-response curves for SP and NKB were rightwardly shifted by atropine. The treatment with atropine brought out latency in the responses for NKB. In the strip preparations, SP did not substantially induce contractions, but NKA and NKB produced twitch-like contractions after latent periods of 28 and 36 sec, respectively. The efficacy of NKA was similar to that in segment preparations, while that of NKB was much lower in strip preparations. Unlike in segment preparations, atropine did not inhibit contrac tions induced by the two tachykinins in strip preparations. These results suggest that tachykinins induce con tractions through myogenic and neurogenic mechanisms, the latter of which may be inoperative in strip preparations.

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“…Hence, tone in longitudinal muscle may be affected by contractile activity of the circular muscle in the segment preparation. We previously reported that the circular muscle in the guinea pig ileum exhibited spontaneous phasic contractions of small amplitude (less than 0.1 g) in the intact segment preparation (9). It thererfore seems possible that drugs which induce contraction or increase the spontaneous activity in circular muscle cause elongation of the longitudinal muscle and thereby reduce the tone of longitudinal muscle.…”

Section: Discussionmentioning

confidence: 99%

Spontaneous Tone in Different Types of Longitudinal Muscle Preparations of Guinea Pig Ileum

Suzuki

Shibayama

Mambo

et al. 1995

Japanese Journal of Pharmacology

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ABSTRACT-Spontaneous tone of longitudinal muscle in guinea pig ileum was investigated in three types of preparations, intact segment preparation, segment preparation deprived of the mucosal layer and longitudinal strip preparation. Tone was defined as the sustained contraction that was lost by 10-7 M atropine in the isotonically recorded manner. The magnitudes of tone were constant for at least 3 hr in the two types of segment preparations. Contractions in response to 10-6 M acetylcholine, which were induced 9 times with an interval of 20 min between each induction, were almost identical throughout the period. In the longitudinal strip preparation, on the other hand, the tone gradually decayed and was eventually lost, while the amplitudes of acetylcholine-induced contractions were reciprocally increased. The tone in the intact segment preparation was reduced to 19% of the control by tetrodotoxin (3 x 10-7 M), to 51 % by indomethacin (3 x 10-6 M) and to 26% by 1V6-cyclopentyladenosine (10-7 M), but was not affected by AA-861 (3 x 10-6 M) or CP-96,345 (3 x 10-7 M). In the three types of preparations, the dose-response curves for acetylcholine were alike with similar EC50s. These results suggest that the tone of longitudinal muscle was mainly induced due to neural activity in the myenteric plexus of guinea pig ileum and that sensitivity to acetylcholine was not affected by the neural activity.

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Neurogenic “Off” Contractions Are Mediated by NK2-Receptors in the Circular Muscle of Guinea Pig Ileum

Cited by 7 publications

References 13 publications

Propulsive activity induced by sequential electrical stimulation in the descending colon of the pig

Propulsive activity induced by sequential electrical stimulation in the descending colon of the pig

Tachykinin-Induced Contractions in the Circular Muscle of Guinea Pig Ileum.

Spontaneous Tone in Different Types of Longitudinal Muscle Preparations of Guinea Pig Ileum

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