Adenosine triphosphate-activated inward current in isolated smooth muscle cells from rat vas deferens |
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Authors: | Ken Nakazawa Norio Matsuki |
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Affiliation: | (1) Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, The University of Tokyo, 113 Tokyo, Japan |
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Abstract: | The electrophysiological effect of adenosine triphosphate (ATP) on the enzymatically dispersed smooth muscle cells from rat vas deferens was investigated. ATP always induced depolarization accompanied with a reduction in membrane resistance. In a whole cell voltage clamp experiment, an inward current was recorded when the cell was exposed to ATP-containing solution. The ATP-induced current disappeared within 2min even in the continuous presence of ATP, which may indicate that the cells were desensitized to this compound. The ATP-induced current was also recorded in the cells superfused with 10–5M nicardipine or in the Cs-loaded cells, eliminating the possible involvement of voltage-gated Ca and K current. During cell-attached patch clamp, an elementary current having a mean conductance of 20pS was observed when the intrapipette solution was changed to ATP-containing solution. The estimated zero current potentials of the ATP-activated macroscopic current and elementary current were about 0mV. These results suggest that ATP exerts its transmitter-like action by activating ion channels in smooth muscles. |
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Keywords: | Smooth muscle cells ATP-activated channel purinergic neurotransmission |
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