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Effects of microiontophoretically applied OMF and U-50488 on spontaneous discharges of respiration related units in the region of nucleus of solitary tract of rat

ZHU Guo-Yun, LIN Fu-Sheng, WANG Cong-Quan

Beijing Institute of Pharmacochemistry, Beijing 102205, China

Abstract

It was observed that ohmefentanyl (OMF) and U-50488, when applied microiontophoretically, affected the spontaneous discharges of respiration related units (RRUs) in the nucleus of solitary tract of rat. Of the 44 RRUs recorded, OMF produced depressive effect in 21, excitatory in 7, biphasic effect in 5 while 11 units were not affected. Naloxone administered iontophoretically blocked both the depressive (6 out of 7) and the excitatory units (2 out of 3). Of the 45 RRUs recorded, U-50488 produced depressive effect in 15, excitatory in 5, biphasic effect in 3, while 22 units were not affected. Naloxone blocked both the U-50488 depression (7 out of 9) and excitation (1 out of 2) effect. U-50488 antagonized OMF-induced depression in 4 out of 6 units. The results suggest that depression and excitation produced by OMF and U-50488 may be mediated by different subtypes of opiate receptor.

Key words: OMF; U-50488; microiontophoresis; respiration related units; opiate receptor

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Citing This Article：

ZHU Guo-Yun, LIN Fu-Sheng, WANG Cong-Quan. Effects of microiontophoretically applied OMF and U-50488 on spontaneous discharges of respiration related units in the region of nucleus of solitary tract of rat. Acta Physiol Sin 1992; 44 (6): 562-568 (in Chinese with English abstract).