Modulatory Effects of Tetrathylpyrazine on the Membrane Response Mediated by Purinoceptors in the Paravertebral Sympathetic Ganglion of Toad
Liang Shangdong (Dept. of Laboratory Animal Science, Jiangxi Medical College, Nanchang)
In the isolated and superfused paravertebral sympthetic ganglion of toad, the surface potentials of the ganglion were recorded with the extracellular microelectrode technique. The modulatory effects of tetrathylpyrazine (TMP)on the membrane response mediated by purinoceptors were observed in the present study. In the ganglion adenosine 5'-triphosphate (ATP) (300μmol/L) induced a depolarization (n=62), a hyperpolarization (n=27) or a biphasic response which appeared a fast depolarization followed by a slow hyperpolarization(n=9). P 2-purinoceptor antagonist trypan blue (500μmol/L) inhibited the depolarization caused by ATP(n=8); P 1-purinoceptor antagonist aminophylline (200μmol/L) depressed the hyperpolarization induced by ATP (n=7). When TMP (1～5mmol/L) was applied in the bath there appeared no significant change in the surface potential of the ganglion. The exogenous cyclic adenosine monophosphate (cAMP) (250μmol/L) could mimic the hyperpolarizing response to ATP(n=10). TMP (3mmol/L) attenuated the ATP-induced depolarization by 53.9±9.5%(n=14,P0.01) and augmented the ATP-induced hyperpolarization by 105.4±24.5% (n=12, P0.01). In the same preparation TMP potentiated the cAMP-induced hyperpolarization (n=4). On the biphasic response caused by ATP, TMP depressed the initial depolarizing phase and enhanced the following hyperpolarizing phase (n=3).
【CateGory Index】： R965