Effects of ions and drugs on the smooth muscle cell membrane of the guinea-pig urinary bladder
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説明
1. Increase in [Ca++] abolished spontaneous action potentials in the guinea-pig urinary bladder and increased the amplitude and rate of rise of evoked spikes. 2. In Ca-deficient solutions, the membrane was depolarized and action potentials occurred in bursts, often terminating in a sustained depolarization. 3. Substitution of NaCl with sucrose (1/10 Na+ remaining as NaHCO3) produced transient hyperpolarization followed by return to the original level. The amplitude and rate of rise of spikes were progressively reduced. 4. Substitution with tris chloride produced depolarization and increase in membrane resistance. The rise time of the spike was prolonged but the amplitude was only slightly reduced. On addition of Ca++ to 4 x the resting potential was restored and rise time reduced. 5. Addition of Mn++ to normal Krebs or 1/2 Na+ (tris) Krebs prolonged the action potential and decreased the amplitude without affecting the resting membrane potential. 6. The electrical activity was unchanged in the presence of tetrodotoxin (2×10−7 g/ml). 7. The frequency of spontaneous spikes was decreased by adrenaline or noradrenaline (5×10−5 g/ml) and increased by acetylcholine (1×10−7 g/ml). Nicotine (1×10−4 g/ml) produced a slight increase in frequency. Atropine completely blocked the action of acetylcholine.
収録刊行物
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- Pfl�gers Archiv European Journal of Physiology
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Pfl�gers Archiv European Journal of Physiology 326 127-141, 1971-01-01
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