Mechanisms underlying intracellular signal transduction of the slow IPSP in submucous neurones of the guinea‐pig caecum.

Mihara, S.; Hirai, Keiji; Katayama, Yoshifumi; Nishi, S.

doi:10.1113/jphysiol.1991.sp018570

Cited by 10 publications

(2 citation statements)

References 50 publications

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“…Hyperpolarization of the cell membrane was associated with a reduction in the amplitude of the slow IPSP, which had a reversal (null) potential of -93 + 6 mV (n = 3; range, -87 to -104 mV). Thus, as has been shown in previous studies (Hirst & McKirdy, 1975;Mihara et al 1985; Surprenant & North, 1988;Mihara, Hirai, Katayama & Nishi, 1991), the slow IPSP appears to be mediated by the influx of K+ ions.…”

Section: Slow Ipsps In Submucosal Neurones Of the Guinea-pig Proximalsupporting

confidence: 81%

Electrophysiological characteristics of submucosal neurones in the proximal colon of guinea‐pigs: comparisons with caecum and descending colon

Cunningham

Hirai²,

Mihara³

et al. 1997

Experimental Physiology

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SUMMARYA systematic examination has been made of' the active and passive electrophysiological properties and synaptic inputs of forty-four randomly impaled submucosal neurones in the proximal colon of the guinea-pig to compare these characteristics directly with those of submucosal neurones in the caecum (n = 70) and descending colon (n = 45). Within each of the three electrophysiological classes of submucosal neurones identified (S, S/AH and AH), no statistically significant regional differences were found with respect to the resting membrane potential, membrane time constant or input resistance between neurones of the proximal colon, descending colon and caecum. Of submucosal neurones from the proximal colon, forty-three of forty-four (98%) received fast excitatory synaptic potentials (fast EPSPs); thirty-nine (91 Oo) were S neurones and the others were S/AH neurones; only one of the forty-four cells (2 %) was an AH neurone. An idazoxan-sensitive slow inhibitory postsynaptic potential (slow IPSP) was induced in thirty of forty-three S and S/AH neurones (70 %) of the proximal colon, compared with sixty-one of sixty-six caecal neurones (92 %) and twelve of forty-one neurones (29'%) in the descending colon. The mean (+ S.E.M.) amplitude of the slow IPSP in proximal colonic neurones was 17 + 1 mV (range, 6-30 mV; n = 30), compared with the significantly larger synaptic response (25 + 1 mV; range, 7-38 mV; n = 66; P < 0.05) recorded in the caecum; the mean slow IPSP amplitude in the descending colon was significantly smaller (12 + 2 mV; range, 5-27 mV; n = 12; P < 0 05) than that in the caecum. In the proximal colon and caecum, only those neurones with a slow IPSP had a hyperpolarizing response to noradrenaline, whereas about 50 % of those neurones of the descending colon that lacked a slow IPSP were hyperpolarized by noradrenaline, acting via a2-adrenoceptors. Thus, the electrophysiological characteristics of the submucosal neurones of the proximal colon more closely resemble those of the caecum than those of the descending colon, of which many do not have a functional noradrenergic synaptic input. Furthermore, the results confirm that there are fundamental regional differences in the guinea-pig large intestine with respect to the synaptic organization of submucosal neurones of particular electrophysiological classes.

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Section: Slow Ipsps In Submucosal Neurones Of the Guinea-pig Proximalsupporting

confidence: 81%

Electrophysiological characteristics of submucosal neurones in the proximal colon of guinea‐pigs: comparisons with caecum and descending colon

Cunningham

Hirai²,

Mihara³

et al. 1997

Experimental Physiology

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“…Tokimasa & Akasu (1989) found that 22% of submucous neurones in the caecum had both fast EPSPs and after-hyperpolarizations but classified them as neither S nor AH. In another study of the same tissue, a substantial number of neurones displaying similar properties were classified as S neurones (Mihara, Hirai, Katayama & Nishi, 1991). Our subelassification of porcine AH neurones dependent on whether the cells display fast EPSPs is not without precedent.…”

Section: Electrophysiological Classificationmentioning

confidence: 62%

Electrophysiological properties of neurones in the internal and external submucous plexuses of newborn pig small intestine.

Thomsen¹,

Pearson²,

Larsen³

et al. 1997

The Journal of Physiology

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1. Intracellular microelectrodes were used to identify three major electrophysiological categories of neurone in both the internal and external submucous plexuses of the porcine small intestine. 2. Two classes of neurone with a long-lasting after-hyperpolarization following their action potential were differentiated by the presence or absence of fast excitatory synaptic inputs (EPSPs) and were termed AH neurones. S neurones received fast EPSPs but did not display after-hyperpolarizations. 3. The mean resting membrane potentials of the three groups of neurones showed a similar trend in both plexuses, with significantly higher values for the two populations of AH neurone than for S neurones. No significant variation of input resistance with cell type was detected. Neuronal input resistance was significantly greater in the internal submucous plexus than in the external submucous plexus. 4. Over 80% of AH neurones in the internal submucous plexus displayed fast EPSPs but a similar percentage of AH neurones in the external submucous plexus did not show fast EPSPs. S neurones constituted 60% of cells studied in the internal submucous plexus but less than 30 % of the cell population in the external submucous plexus. 5. This study of porcine submucous neurones has revealed both similarities and differences to previous work in the guinea-pig small intestine. The most contrasting features are the relative abundance and subclassification of AH neurones in the pig in addition to the apparent paucity of slow synaptic potentials. The differences in the neuronal profiles of the internal and external submucous plexuses may reflect a differentiation of function between the two enteric nerve networks.

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Responsiveness to ATP with an increase in intracellular free Ca2+ is not a distinctive feature of calbindin-D28 immunoreactive neurons in myenteric ganglia

et al. 1996

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Mechanisms underlying intracellular signal transduction of the slow IPSP in submucous neurones of the guinea‐pig caecum.

Cited by 10 publications

References 50 publications

Electrophysiological characteristics of submucosal neurones in the proximal colon of guinea‐pigs: comparisons with caecum and descending colon

Electrophysiological characteristics of submucosal neurones in the proximal colon of guinea‐pigs: comparisons with caecum and descending colon

Electrophysiological properties of neurones in the internal and external submucous plexuses of newborn pig small intestine.

Responsiveness to ATP with an increase in intracellular free Ca2+ is not a distinctive feature of calbindin-D28 immunoreactive neurons in myenteric ganglia

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