The Effects of Nickel and Cobalt Ions on the Spontaneous Electrical Activity, Slow Wave, in the Circular Muscle of the Guinea-pig Gastric Antrum

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概要

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• 1. Circular muscle strips of the guinea-pig gastric muscle produced spontaneous electrical activity in the form of slow waves. The slow wave amplitude, maximum rate of rise, duration, and frequency were 31 mV, 60 mV sec^<-1>, 4.3 sec, and 4.3 min^<-1> on average, respectively. These parameters were not appreciably affected by 3 μM nifedipine or nicardipine, even following membrane depolarization with 60 mM K^+. 2. Ni^<2+> (1-100 μM) increased slow wave amplitude and frequency, but reduced the rate of rise, accompanied by membrane depolarization. The rate of rise and depolarization slowly recovered to the control values in the continuous presence of Ni^<2+>, but slow wave frequency remained high. The recovery after wash-out was very poor particularly when a high concentration of Ni^<2+> was applied. 3. The effects of Co^<2+> were fundamentally the same as those of Ni^<2+>. 4. Removal of external Ca^<2+> slowly reduced the rate of rise and amplitude of the slow waves in the absence and the presence of Ni^<2+> and Co^<2+>, although the effects were reduced in the presence of these metal ions. 5. Concentrations of Ni^<2+> and Co^<2+> greater than 1 mM suppressed the slow waves. However, when the external Na^<2+> was replaced with N-methyl-D-glucamine during the suppression, nearly normal electrical activity was resumed. 6. Since slow waves were not significantly affected by nifedipine (3 μM) and Ni^<2+> (100 μM), the inward currents generating slow waves do not seem to flow through L-type Ca^<2+> channels or typical T-type Ca^<2+> channels. Slow waves are probably potentiated by Ni^<2+> and Co^<2+> acting intracellularly. These ions at higher concentrations seem to inhibit the pacemaker activity more powerfully than they do the inward currents responsible for slow wave generation.

• 日本平滑筋学会の論文

著者

• Tomita Tadao

  Division Of Smooth Muscle Research Institute For Comprehensive Medical Science Fujita Health Univers

• Pang Yi-wet

  Department Of Physiology School Of Medicine Nagoya University

• OGINO Kayo

  Division of Smooth Muscle Research, Institute for Comprehensive Medical Science, Fujita Health Unive

• Ogino Kayo

  Division Of Smooth Muscle Research Institute For Comprehensive Medical Science Fujita Health Univers

関連論文

• The Effects of Nickel and Cobalt Ions on the Spontaneous Electrical Activity, Slow Wave, in the Circular Muscle of the Guinea-pig Gastric Antrum

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