Basic mechanism of caloric response using isolated frog labyrinth

用离体牛蛙半规管和椭圆形研究了热量反应的基本机制。首先，整块切除膜迷路以研究内淋巴流的动态转导。当刺激前管时，从髓前神经诱发出兴奋性动作电位。同时，通过后神经诱发抑制性反应。因此，内淋巴流作用于迷路的一部分，通过动态转导导致其他器官的体液转移。后半规管周围淋巴间隙加入氨基糖苷类药物后，动作电位被抑制。因此，外淋巴液的离子环境对于维持前庭感觉细胞的功能是必不可少的。最后，半规管和椭圆囊受到热对流的刺激，因为热反应是由内淋巴中的热对流流体引起的。冻结的林格溶液被用来产生沿引力面的热对流。热对流刺激半规管时，根据热对流的方向可观察到兴奋反应和抑制反应。因此，热对流是一种对感觉细胞有效的机械刺激。当不同方向的热对流刺激椭圆囊时，无论是什么刺激，反应都是相同的。这表明椭圆体具有相同的定向兴奋性，因此可能受失重条件的影响最大。

Basic mechanism of caloric response was studied using isolated bull frog semicircular canal and utricle. First, the membranous labylinth was en bloc removed to study dynamic transduction of the endolymphatic flow. When the anterior canal was stimulated, an excitatory action potential was evoked from the anterior amullary nerve. At the same time, an inhibitory response was induced through the posterior nerve. Therefore, the endolymphatic flow applied to a part of the labyrinth leads to a systemic fluid shift in other organ through dynamic transduction. When an aminoglycoside drug was added to the perilymphatic space of the posterior semicircular canal, the action potential was inhibited. Therefore, ionic environment of the perilymph is essential for maintaining a function of the vestibular sensory cell. Finally, the semicircular canal and utricle were stimulated by thermoconvection, since caloric response is induced by thermoconvective fluid flow in the endolymph. Frozen Ringer's solution was used to produce thermoconvective flow along the gravitational plane. When a semicircular canal was stimulated by thermoconvection, excitatory and inhibotory responses were observed according to the direction of the thermoconvection. Therefore, thermoconvective flow serves as a valid mechanical stimulus to the sensory cells. When the utricle was stimulated by thermoconvection with different directions, the responses were the same regardless of the stimuli. This indicates that the utricle has an equal directional excitability, thus might be most influenced by weightless condition.