Effects of potassium on membrane potential, spike discharge, and tension in taenia coli

Shimo, Yasuo; Holland, William C.

doi:10.1152/ajplegacy.1966.211.6.1299

Cited by 46 publications

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“…It was also reported that an acid extracellular pH decreased the glucose uptake in the rat heart (14). These findings cited above might explain some possible mechanism of the inhibition by low external pH or low concentration of sodium bicarbonate in the medium on the K-contracture, the phasic phase of which was said to be initiated by the released of tissue calcium (3)(4)(5) and the tonic phase diminished when external glucose was removed from the external medium (3), but no experimental evidence has been ob tained in the case of taenia coli. Total calcium content of taenia coli kept in the phosphate-free Krebs-Ringer (2.8 mm Ca/kg fresh wt.)…”

Section: Sodium Phosphatementioning

confidence: 76%

“…Phasic contraction was said to be initiated by the passive process of release of calcium from a cellular site whereas tonic contracture by the active transmembrane calcium transport linked to metabolism (3)(4)(5). If the process(es) common to both phases should exist, it (they) may be before and/or after than the aformentioned processes.…”

Section: Sodium Phosphatementioning

confidence: 99%

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Influences of External Magnesium, Bicarbonate and Phosphate on Potassium-Induced Contracture of the Guinea Pig Taenia Coli

Karaki

Urakawa

Ikeda

1966

Japanese Journal of Pharmacology

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It was reported that high-potassium (K) solution produced a contracture (K-induced contracture) in the guinea pig taenia coli, and the tension development in the muscle depolarized with high-K was dependent on calcium (1, 2), and that "Ca uptake and ex changeable fraction of cellular Ca increased with high-K (2).Furthermore, it was demonstrated that K-induced contracture was composed of phasic and tonic phases and was proposed that in the phasic contraction, sufficient calcium was released from a cellular site to initiate contraction, whereas in the tonic contraction, enough calcium crossed the membrane to initiate it and that the transmembrane calcium transport involved in the latter response was dependent on metabolism (3). On the basis of these results, the role of metabolism in the K-induced contracture of taenia coli was examined by the use of various metabolic intermediates, inhibitors of metabolism and active transport, revealing that the factors such as substrate removal, a decrease of tem perature, DNP, ouabain and a substitution of external sodium chloride with lithium chloride abolished the tonic response whereas the same factors had little or no effect on the phasic response.Hence it was considered that the phasic response was a passive process, while the tonic contraction was an active one depending on metabolism and possibly linked to active Na transport (4). This consideration was also supported by the electrophysiological experiments (5).In the present paper, further evidence was obtained concerning to the influences of the physiological components in the external media, that is, magnesium chloride (MgCl2), sodium bicarbonate (NaHCO3) and sodium phosphate (NaH2PO4) on the K-induced tension development of taenia coli. METHODSStrips of taenia coli (30-40 mg) were isolated from male guinea pigs weighing about 500 g. The excision of the muscle was endeavoured to avoid the Auerbach's plexus which includes the excitatory cholinergic nerve and intramural inhibitory nerve (6).

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Section: Sodium Phosphatementioning

confidence: 76%

Section: Sodium Phosphatementioning

confidence: 99%

Influences of External Magnesium, Bicarbonate and Phosphate on Potassium-Induced Contracture of the Guinea Pig Taenia Coli

Karaki

Urakawa

Ikeda

1966

Japanese Journal of Pharmacology

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“…Only an initial transient contraction is induced by high K (and also by carbachol) in the presence of Ca antagonists like verapamil (Riemer et al, 1974;Karaki et al, 1984), D600 (Brading & Sneddon, 1980), ruthenium red (Kawamura & Yabu, 1978), cyproheptadine (Lowe et al, 1981) and N2-dansyl-L-arginine-4-t-butylpiperidine amide (TI 233) (Karaki et al, 1983c), inhibitors of aerobic metabolism (Pfaffman et al, 1965;Ferrari & Carpenedo, 1968 ;Tsuda et al, 1977;Nakagawa et al, 1984), inhibitors of the Na pump like ouabain (Pfaffman et al, 1965;Kishimoto & Urakawa, 1982a), Li substitution for Na (Pfaffman et al, 1965;Kishimoto & Urakawa, 1982a), and ionophores with mitochondrial inhibiting action like monensin and X-537A (Ishida & Shibata, 1982;Murakami et al, 1983). The initial transient contraction induced by high K in taenia coli coinsides with a burst of spike discharges (Shimo & Holland, 1966). This electrical change, as well as initial transient contraction, is relatively insensitive to the inhibitory effects of Mn (Brading et al, 1969) and D600 (Inomata & Kao, 1976).…”

Section: Initial Transient and Following Sustained Contractionsmentioning

confidence: 99%

“…In rabbit aorta, an increase in external K concentration induces only a graded depolarization (Mekata, 1976). In taenia coli, as well as in other spike-generating smooth muscles like uterus, vas deferens and ureter, an increase in the external K concentration induces a burst of spike discharges followed by a spike-free membrane depolarization (Burnstock et al, 1963;Shimo & Holland, 1966 ;Bolton, 1972;Johnishi & Sunano, 1978). In guinea pig portal vein, a hyperosmotic solution itself depolarizes the membrane (Kuriyama et al, 1971).…”

Section: Introductionmentioning

confidence: 99%

Potassium-induced contraction in smooth muscle.

Karaki

Urakawa

1984

Jpn. J. Smooth Muscle Res.

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“…The tonic contraction results from a steady depolarization, and the coupling between the depolarization and the contractile system is Ca and metabolism-dependent (14,15). Clonidine was scarcely effective in altering the 80 mM potassium-induced response at a 0.3 mM level.…”

Section: Effects Of Clonidine On 80 Nial Potassium-in(hiced Responsementioning

confidence: 99%

Effects of Clonidine on Excitation-Contraction in Guinea-Pig Taenia Coli

Houki

1972

Jpn.J.Pharmacol

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Among the effects of clonidine [St 155, 2-(2,6-dichlorophenylamino)-2-imidazoline hydrochloride], those on the cardiovascular system have received considerable attention.Clonidine induces a biphasic change in blood pressure, consisting of initial brief hypertension and subsequent long-lasting hypotension (1). The initial hypertension has been explained by a sympathomimetic action of this drug and the subsequent hypotension by some centrally mediated repression of the sympathetic tone (2-5).
The isolated preparation of taenia coil is an excellent material to study sympathomimetic and parasympathomimetic actions of drugs, responding to the former with inhibition and to the latter with excitation (6,7). The present paper reports the effects of clonidine on the excitation and contraction of taenia coll. The knowledge obtained with this material will be useful to interpret the drug actions on smooth muscle in general. MATERIAL AND METHODSAll experiments were performed with taenia coli isolated from guinea-pig. The animal was sacrificed by a blow on the head. A piece of taenia coli, about 2 cm long in situ, was dissected free from the underlying tissue after the abdomen was opened and the colon exposed. The sucrose-gap method invented by Sldmpfli (8) was used to record the electrical activity. The recording chamber employed in the present study was modified according to Washizu (9). Potential changes and isometric contractions were simulta neously recorded with a pen-writing oscillograph.The Tyrode solution used was of the following composition (mM): NaCI, 137; KCI, 4; MgCI.,, 1.2; CaCl.,, 2.5; NaHCO, 12; NaHPO_,, 0.4; and glucose, 11. The solution with 20 or 80 mM K+ level was prepared by increasing KCI in an appropriate amount and by reducing equimolar NaCl without changing the concentrations of other salts. The Tyrode or test solution applied to the preparation was warmed up to 37 L. and aerated with a gas mixture of 95°; 0, and 5°" CO,. The drugs used were as follows: clonidine hydrochloride (C.H. Boehringer Sohn), atropine sulfate (Wako) and tetrodotoxin (Sankyo). These drugs were applied to the preparation by being freshly dissolved in the bath saline. RESULTS1. Effects of c'lnaidiac na spike dischca'gc rate contraction C lonlChne enhanced the rate and alllplltude of spontaneous spike discharge of taenia

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Effects of potassium on membrane potential, spike discharge, and tension in taenia coli

Cited by 46 publications

References 0 publications

Influences of External Magnesium, Bicarbonate and Phosphate on Potassium-Induced Contracture of the Guinea Pig Taenia Coli

Influences of External Magnesium, Bicarbonate and Phosphate on Potassium-Induced Contracture of the Guinea Pig Taenia Coli

Potassium-induced contraction in smooth muscle.

Effects of Clonidine on Excitation-Contraction in Guinea-Pig Taenia Coli

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