Identification and Transduction Mechanisms in Chemoreceptor Cells

1.使用犬味觉系统研究了盐、甜味物质和鲜味物质的味觉受体机制。结果表明，阿米洛利对NaCl、KCl和NH_4Cl等盐的反应有抑制作用。这种抑制的盐响应的解释由吸附的阿米洛利阳离子的盐受体网站。盐的存在大大增强了对糖的反应。这种增强被解释为糖受体之间的协同性增加。结果发现，犬的味觉系统对鲜味物质反应敏感。阿米洛利抑制对谷氨酸单酯（MSG）的反应，但不抑制对鸟苷酸二钠（GMP）的反应或由MSG与GMP的协同作用引起的反应。这些结果表明，对味精的反应是由盐反应组成的，对GMP单独或协同作用的反应是由鲜味反应组成的.利用海龟嗅觉系统研究了嗅觉受体机制。将交叉适应方法应用于龟类嗅觉系统，定量测定了龟类对不同气味物质的辨别能力。该方法为嗅觉系统构效关系的研究开辟了新的途径。用无盐溶液灌注海龟的嗅觉系统，不改变嗅觉对各种气味的反应，这表明位于嗅觉纤毛的阳离子通道对在体嗅觉系统没有贡献。研究发现，由磷脂酰胆碱（PC）和磷脂酰丝氨酸（PS）组成的脂质体对多种气味物质有敏感的响应。脂质体（PS/PC = 0.2）对醋酸戊酯的敏感性远高于海龟或青蛙嗅觉系统。

1. Taste receptor mechanisms for salts, sweet substances and umami substances were investigated using the canine taste system. It was found that amiloride suppresses the responses to salts including NaCl, KCI and NH_4Cl. This suppression of the salt response was explained by adsorption of amiloride cation on the salt receptor sites. The responses to sugars were greatly enhanced by the presence of salts. The enhancement was explained by an increase in cooperativity between sugar receptors. It was found that canine taste system responds sensitively to umami substances. The response to monosodium glutamate (MSG) was suppressed by amiloride, but the response to disodium guanylate (GMP) or that induced by synergism between MSG and GMP was not suppressed by amiloride. These results suggested that the response to MSG is composed of salt response and the response to GMP alone or that induced by synergism is composed of umami response.2. Olfactory receptor mechanisms were investigated using the turtle olfactory system. The cross adaptation method was applied to the turtle olfactory system and discrimination of various odorants was quantitatively measured. This method opened the way to study the structure-activity relationship in olfactory system. Perfusion of the turtle olfactory system with salt free solution unchanged the olfactory responsed to various odorants, suggesting that cation channels located at olfactory cilia do not contribute to in vivo olfactory system. It was found that liposomes composed of phosphatidylcholine (PC) and phosphatidylserine (PS) respond sensitively to various odorants. The sensitivity of the liposomes (PS/PC = 0.2) to amyl acetate was much higher than that of the turtle or the frog olfactory system.