Difference between substance P- and acetylcholine-induced currents in mammalian smooth muscle cells. |
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| Authors: | K Nakazawa K Inoue K Fujimori A Takanaka |
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| Institution: | Division of Pharmacology, National Institute of Hygienic Sciences, Tokyo, Japan. |
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| Abstract: | The effects of substance P (SP) and acetylcholine (ACh) on membrane currents were compared using freshly isolated smooth muscle cells from guinea-pig ileum. Both SP (100 nM) and ACh (10 microM) induced inward currents at negative holding potentials. The ACh-induced current, but not the SP-induced current, showed relaxation upon voltage-stepping. The SP-induced current was increased by hyperpolarization more negative than -50 mV whereas the ACh-induced current was decreased by hyperpolarization. The results suggest that the SP-induced inward current is elicited via an ionic pathway different from that involved with ACh-activated channels. |
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