Some Electrical Properties of the Slow Potential Changes Recorded From the Guinea Pig Stomach in Relation to Drug Action

Magaribuchi, Tetsuo; Ohbu, Teruyoshi; Sakamoto, Youichi; Yamämoto, Yasushi

doi:10.2170/jjphysiol.22.333

Cited by 16 publications

(16 citation statements)

References 34 publications

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“…However, this possibility has not been accepted due to the detection of similar forms of slow wave during altered activities of the Na-K pump [1]. An involvement of fast Na-channels in the depolarizing phase of slow waves was initially proposed from the experiments which found that tetrodotoxin, a blocker of Na-channels, inhibited slow waves in the guinea-pig stomach [68,69]. However, these results were not confirmed in later experiments [56].…”

Section: Cellular Mechanisms Of Spontaneous Activity In Gastric Smootmentioning

confidence: 99%

“…Voltage clamp experiments using double sucrose-gap methods indicate that currents flow inwardly during the generation of either the voltage-sensitive or the voltage-insensitive components of slow waves [56]. The ionic conductance of the membrane estimated from the amplitudes of electrotonic potential increases during the generation of slow waves [1,69], suggesting that the second component of the slow waves is produced by ions whose equilibrium potentials distribute more positive than the resting membrane potential.…”

Section: Cellular Mechanisms Of Spontaneous Activity In Gastric Smootmentioning

confidence: 99%

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Cellular Mechanisms of Myogenic Activity in Gastric Smooth Muscle.

Suzuki

2000

JJP

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Many types of smooth muscle contract spontaneously, with each contraction being accompanied by a slow rhythmic oscillation of the membrane potential (slow wave), a discharge of spike potentials or both [1]. The spontaneous generation of a single spike or bursts of spikes is detected in smooth muscles of the urinary bladder, the uterus (longitudinal muscle layer), the prostate, the isolated longitudinal muscle of the intestine or the portal vein. Slow waves are observed in smooth muscle of the stomach, the circular layer of the intestine and uterus of many species, the renal pelvis, the urethra and the ureter. In several of these muscles, spike potentials are followed. These include the renal pelvis, ureter, uterus (circular muscle), lymphatic vessels and the urethra [2]. As many enteric nerves generate bursts of activity, the transmitters released from these nerves can modulate the activity of smooth muscles [3], and there is a possibility that smooth muscle activity could result indirectly as a consequence of neuronal activity. However, this is rarely the cause of muscle activity since many smooth muscles remain active after neuronal activity has been that ICC may also be the pacemaker cells responsible for gastric activity. However, isolated circular smooth muscle tissues spontaneously generate regenerative potentials, suggesting that there are at least two sites for the initiation of spontaneous activity in the stomach. Regenerative potentials persist in the presence of Ca-antagonists and are inhibited by agents which disrupt intracellular Ca 2ϩ homeostasis. Depolarization of the membrane elicits regenerative potentials after a long delay and the potentials have long refractory periods. This suggests that an unidentified 2nd messenger may be formed during the delay between membrane depolarization and the initiation of a regenerative potential. In gastric muscles of mutant mice which do not express inositol trisphosphate (InsP 3 ) receptors, spike potentials but not slow waves are generated, suggesting the possible involvement of InsP 3 in the initiation of spontaneous activity.

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Section: Cellular Mechanisms Of Spontaneous Activity In Gastric Smootmentioning

confidence: 99%

Section: Cellular Mechanisms Of Spontaneous Activity In Gastric Smootmentioning

confidence: 99%

Cellular Mechanisms of Myogenic Activity in Gastric Smooth Muscle.

Suzuki

2000

JJP

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“…The spike generated on the slow potential changes is thought to be due to the influx of Ca with cessation of the spike in Ca-free solution or in the presence of MnCl2. However, there are at least two different components related to the slow potential changes, as determined under conditions of various ionic environments (Magaribuchi, Ohbu, Sakamoto & Yamamoto, 1972;Osa & Kuriyama, 1970;Ohba, Sakamoto & Tomita, 1975.…”

Section: Introductionmentioning

confidence: 99%

“…The evoked mechanical response could be recorded simultaneously with generations of slow potential changes and, when the spike was superimposed on the slow potential change, the additional contraction superimposed on the contraction induced by the slow potential change (Magaribuchi et al 1972). The mechanical response, therefore, is thought to be generated by the voltage-dependent Ca influx and, in part, by release of the stored Ca in the cell (Kuriyama, Mishima & Suzuki, 1975).…”

Section: Introductionmentioning

confidence: 99%

Effects of calcium and manganese ions on mechanical properties of intact and skinned muscles from the guinea‐pig stomach

Itoh

Kuriyama

Nanjo

1982

The Journal of Physiology

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SUMMARY1. To investigate the mechanism of generation of contractions in tissues from the guinea-pig stomach, the effects of caffeine, procaine, acetylcholine (ACh), diltiazem or MnCl2 on the contraction evoked from small bundles of intact or skinned muscles (50 ,um in width and 250-300 ,um in length) were observed.2. All these agents except for ACh blocked the spontaneously generated contraction. Diltiazem (1 x 10-4 M) had no effect and MnCl2 (3 mM) slightly reduced and caffeine enhanced the tonic contraction evoked in Na-free solution, whereas procaine relaxed the tissue. On the other hand, in the isotonic [K]0 solution, diltiazem, MnCl2 and procaine relaxed the tissue, while caffeine enhanced the tonic contraction.3. Under pre-treatment with Ca-free solution (2 mM-EGTA-containing solution) after depletion of the stored Ca, application of 2-5 mM-Ca and subsequently applied 5 mM-caffeine produced contractions (Ca-and caffeine-induced contractions, respectively). In polarized (5-9 mM-K.) and depolarized (128 mM-KO) muscles, the various agents simultaneously applied with 2-5 mM-Ca modified the amplitude of the Ca-induced and the resulting caffeine-induced contractions. Thus, at least three different Ca influxes required to evoke the Ca-or caffeine-induced contraction were identified; diltiazem-sensitive Ca influx, diltiazem-insensitive but Mn-sensitive Ca influx and Mn-insensitive Ca influx.4. The Ca-and caffeine-induced contractions in Ca-free and 15-5 mM-Na-containing solutions were gradually reduced in amplitude, in proportion to the time of exposure. However, amplitude of the caffeine-induced contractions was inhibited to a greater extent and the duration of the contracts was less prolonged than the case of the Ca-induced contraction.5. In saponin-treated skinned muscles, the minimum concentration of Ca required to produce the contraction was 1 x 10-7 M, and the maximum contraction was evoked by application of 1 x 10-5 M-Ca. The effects ofNa-free solution on the Ca accumulation and release to and from the storage site were also observed in these skinned muscles.

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“…In the electrophysiological studies (PAPASOVA et al,1968;KURIYAMA et al, 1970;FUJII,1971;MAGARIBUCHI et al,1972;ITO and KURIYAMA,1975),it has reported that the smooth muscle from the stomach of the guinea-pig and cat exhibited a spontaneous electrical activity which was consisted of slow waves with or without spike generation being superimposed on them.Responses of the stom-ach to catecholamines were complicated.The generation of the slow waves was blocked or suppressed by catecholamines and the inhibitory action of catecholamines was almost completely blocked by phentolamine (MAGARIBUCHI et al, 1972;ITO and KURIYAMA,1975)while the relaxation produced by catecholamines was partially blocked either by alpha or beta adrenergic blocking agents (GUIMA-RAES,1969;BAILEY,1971).However it was also reported that the excitatory response to phenylephrine and the excitatory component of biphasic response to adrenaline and noradrenaline were inhibited by alpha adrenergic blocking agents (GUIMARAES,1969;BAILEY,1971).…”

Section: Introductionmentioning

confidence: 99%

Evidences for Alpha Excitatory Action of Catecholamines on the Electrical Activity of the Guinea-Pig Stomach

Ohkawa

1976

Jpn.J.Physiol

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Effects of catecholamines and their inhibitors on the electrical activity of the smooth muscle of the guinea-pig stomach were studied by using pressure electrodes.The spontaneous electrical activity of antrum and corpus preparations consisted of slow waves with or without superimposed spikes.In quiescent fundus preparations,the spike activity and slow waves were generated by TEA.Catecholamines(noradrenaline, isoprenaline and adrenaline)suppressed or blocked the spike discharges and the generation of slow waves.However,the spike activity was enhanced at a higher concentration of phenylephrine in the antrum and fundus preparations.Inhibitory responses of the smooth muscles from whole regions to adrenaline,noradrenaline or isoprenaline were antagonized by propranolol or DCI but not by phentolamine or phenoxybenzamine.Therefore,inhibitory actions of these amines appear to involve beta-adrenoceptors.After treatment with tetrodotoxin,noradrenaline and isoprenaline blocked the spike activity and the generation of slow waves.Phenylephrine or adrenaline potentiated the spike activity in the presence of tetrodotoxin.After treatment with DCI or propranolol,phenylephrine potentiated the spike activity of the antrum and fundus preparations.These excitatory effects were antagonized by phentolamine or phenoxybenzamine.It is concluded that excitatory actions of these amines are mediated by alpha-adrenoceptors rather than via a nervous pathway.

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Some Electrical Properties of the Slow Potential Changes Recorded From the Guinea Pig Stomach in Relation to Drug Action

Cited by 16 publications

References 34 publications

Cellular Mechanisms of Myogenic Activity in Gastric Smooth Muscle.

Cellular Mechanisms of Myogenic Activity in Gastric Smooth Muscle.

Effects of calcium and manganese ions on mechanical properties of intact and skinned muscles from the guinea‐pig stomach

Evidences for Alpha Excitatory Action of Catecholamines on the Electrical Activity of the Guinea-Pig Stomach

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