Electrophysiological aspects of regulation of precapillary vessel tone in smooth muscles of vascular tissues.
The tone of precapillary vessels is regulated by free-Ca concentrations in the myoplasm. If the concentration of Ca decreases below 10(-7) M, the muscle relaxes. Maximal amplitudes of contraction are recorded when the concentration of Ca is higher than 5 X 10(-6) M. Certain aspects of Ca regulation require electrical activity of the cell membrane. To measure the electrical response under resting and active conditions, microelectrode, double-sucrose (current and voltage-clamp techniques), and single-current recording (patch-clamp) methods have been used. Measurements of membrane potential and conductance using the microelectrode method are essential to understand the property of the voltage-dependent Ca influx. It is also essential to make electrophysiological investigations for the analysis of the receptor-activated Ca influx. Excitatory junction potentials are one indicator of the activities of the pre- and postjunctional receptors as well as of the relative amount of transmitter released. Single currents have been recorded with the patch-clamp technique in isolated vascular smooth-muscle cells.
Kuriyama
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H
Kitamura
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D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000378:metabolism; D006801:Humans; D007473:Ion Channels / Q000502:physiology; D008564:Membrane Potentials; D009129:Muscle Tonus; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D009638:Norepinephrine / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D017981:Receptors, Neurotransmitter / Q000502:physiology
D007473:Ion Channels; D017981:Receptors, Neurotransmitter; D011188:Potassium; D002118:Calcium; D009638:Norepinephrine