Re L, Concettoni C, Moretti V, Giusti P, Rossini L
Institute of Experimental and Clinical Medicine, University of Ancona, Italy.
Pharmacol Res. 1991 Oct;24(3):283-94. doi: 10.1016/1043-6618(91)90092-c.
Skin extracts of the Australian frog Pseudophryne coriacea (PsC) potentiate and prolong the bioelectric activity of various excitable tissues. When studied by electrophysiological means in a preparation of mouse diaphragm, PsC skin extracts did not affect the spontaneous acetylcholine (ACh) release. However, the indirect stimulation of the preparation in the presence of PsC skin extracts gave rise to a different profile of rhythmic activity showing afterpotentials and variable oscillatory activity. The action potential and the total sodium current recorded in the muscle fibre with the loose patch clamp method were not modified significantly by the alkaloid. Concentrations of PsC skin extract that did not cause repetitive activity, seemed to reduce slightly the quantal content of the evoked release of ACh. The resting potential of muscle fibres was not modified even by the highest PsC skin extract concentrations. These results suggest that the facilitation effects of PsC skin extracts could be due to intracellular mechanisms probably related to the control of the cytosolic calcium concentrations or to an increased excitability of the presynaptic biomembranes.
澳大利亚蛙（Pseudophryne coriacea，简称PsC）的皮肤提取物可增强并延长各种可兴奋组织的生物电活动。在用小鼠膈肌制备物进行电生理研究时，PsC皮肤提取物不影响乙酰胆碱（ACh）的自发释放。然而，在存在PsC皮肤提取物的情况下对制备物进行间接刺激，会产生不同的节律性活动模式，表现为后电位和可变的振荡活动。用松散膜片钳法记录的肌纤维动作电位和总钠电流并未因该生物碱而发生显著改变。未引起重复活动的PsC皮肤提取物浓度似乎会略微降低诱发释放的ACh的量子含量。即使是最高浓度的PsC皮肤提取物也不会改变肌纤维的静息电位。这些结果表明，PsC皮肤提取物的促进作用可能归因于细胞内机制，这可能与胞质钙浓度的控制或突触前生物膜兴奋性的增加有关。
