Hirobumi Ohkawa

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  • H Ohkawa
  • 1983
The electrical and mechanical activity of the smooth muscle of the guinea-pig prostate gland was studied. The electrical activity of the cells was recorded intracellularly. The resting membrane potential was about -50-60 mV. The majority of cells was electrically quiescent but some cells generated action potentials spontaneously in the normal solution. The(More)
  • H Ohkawa
  • 1982
Spontaneous excitatory junction potentials (e.j.p.s) from the circular smooth muscle cells of the guinea-pig seminal vesicle were recorded intracellularly. Their mean amplitude and frequency were 2.6 mV and 26.6/min, respectively. Occasionally large e.j.p.s were recorded. The circular smooth muscle of the tissue generated the action potential spontaneously,(More)
  • H Ohkawa
  • 1981
Spontaneous contractile activity of the circular smooth muscle of the guinea-pig seminal vesicle consists of twitch-like contractions with a mean frequency of 2.7/min. The amplitude of responses to repetitive stimulation depended on the frequency of stimulation at constant pulse duration and on the pulse durations at constant frequency of stimulation.(More)
  • H Ohkawa
  • 1983
Inhibitory junction potentials (IJPs) in response to single or repetitive stimulation were recorded intracellularly from smooth muscles of the guinea-pig duodenum. The amplitude of the IJP was dependent on the stimulus intensity and duration. The hyperpolarization of up to 30 mV was evoked by a single pulse. The mean values of the latency, the fall time,(More)
Effects of gastrointestinal hormones on electrical and mechanical activity of smooth muscle of cat stomach were studied. Spontaneous electrical activity of the antrum preparation consisted of slow waves with superimposed spike-like potentials. Phasic contractions occurred synchronously with the electrical activity. Pentagastrin, tetragastrin, pancreozymin(More)
  • H Ohkawa
  • 1986
Cholinergic modulation and effects of dynorphin on the non-adrenergic non-cholinergic inhibitory potentials (NANC i.p.s) in the longitudinal smooth muscle cells of the guinea-pig duodenum were studied intracellularly. Atropine (1.4 X 10(-7)-1.4 X 10(-5) M) and scopolamine (3.3 X 10(-8)-3.3 X 10(-7) M) increased the amplitude of the evoked i.p.s while(More)
  • H Ohkawa
  • 1984
Non-adrenergic inhibitory potentials (i.p.'s) were recorded from the smooth muscle cells of the guinea-pig duodenum following field stimulation. ATP, ADP and AMP increased the membrane potential of the cell and decreased the amplitude and the rate of hyperpolarization of the i.p. The amplitudes of the maximum hyperpolarization due to a repeated stimulation(More)
  • H Ohkawa
  • 1982
The membrane activity of the oviductal smooth muscle cell of the nonpregnant guinea pig was studied intracellularly. The membrane potential was about 50 mV. The cells used were spontaneously active in normal solution. Spontaneous action potentials were recorded from the regions of infundibulum, isthmus, and ampulla of the oviduct. Action potentials were(More)
  • H Ohkawa
  • 1976
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(More)
  • H Ohkawa
  • 1983
The inhibitory potentials (i.p.s) in the longitudinal and circular smooth muscle cells of the guinea-pig duodenum were recorded intracellularly. The amplitude and the time course of the i.p.s were similar in both muscle cells. The i.p.s were not blocked by atropine and guanethidine. Thus, the i.p. has non-cholinergic and non-adrenergic nature. Paired pulse(More)