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Taoda M, Adachi YU, Uchihashi Y, Watanabe K, Satoh T, Vizi ES: Effect of dexmedetomidine on the release of [3H]-noradrenaline from rat kidney cortex slices: characterization of alpha2-adrenoceptor. Neurochem Int. 2001 Apr;38(4):317-22.
The presynaptic modulation of [3H]-noradrenaline (NA) release from rat kidney cortex slices, a method used for the first time, was investigated. Rat kidney cortex slices were loaded with [3H]-NA and the release of radioactivity at rest and in response to field stimulation was determined. The alpha (2)-adrenoceptor agonist, dexmedetomidine inhibited the stimulation-evoked release of NA from kidney slices in a concentration-dependent manner, whereas alpha (2)-adrenoceptor antagonist CH-38083 (7,8-methyenedioxy-14-alpha-hydroxyalloberbane HCl), an alpha (2)-adrenoceptor antagonists, enhanced it. When dexmedetomidine and BRL-44408, a selective alpha (2A) antagonist, were added together, the effect of dexmedetomidine was significantly antagonized. In contrast, ARC-239 (2-(2,4-(o-piperazine-1-yl)-ethyl-4,4-dimethyl-1,3-(2H, 4H) disoguinolinedione chloride), a selective alpha (2B)-antagonist, had no effect on the release and failed to prevent the effect of dexmedetomidine. Prazosin, an alpha (1)- and alpha (2B/C)-adrenoceptor antagonist enhanced the release evoked by field stimulation. It is therefore suggested that there is a negative feedback modulation of NA release at the sympathetic innervation of kidney cortex, and dexmedetomidine, a clinically used anesthetic adjunct inhibits the release via activation of alpha (2C)-adrenoceptors. |
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