Identification and Transduction Mechanisms in Chemoreceptor Cells

1.利用犬的味觉系统研究了盐、甜味物质和鲜味物质的味觉感受机制。结果表明，阿米洛利对氯化钠、氯化钾和氯化铵的反应均有抑制作用。这种盐反应的抑制是通过阿米洛利阳离子在盐受体上的吸附来解释的。盐的存在极大地增强了对糖的反应。这种增强的原因是糖受体之间的协作性增加。研究发现，犬的味觉系统对鲜味物质反应敏感。对谷氨酸钠(MSG)的反应可被阿米洛利抑制，但对鸟苷二钠(GMP)或由MSG和GMP协同作用引起的反应不受抑制。这些结果表明，对味精的反应由盐反应组成，对GMP单独的反应或协同作用的反应由umami反应组成。用海龟嗅觉系统研究了嗅觉受体的机制。将交叉适应方法应用于甲鱼嗅觉系统，定量测量了不同气味物质的识别率。该方法为嗅觉系统构效关系的研究开辟了新的途径。用无盐溶液灌流龟的嗅觉系统，嗅觉对各种气味的反应不变，这表明位于嗅纤毛的阳离子通道对体内的嗅觉系统没有贡献。研究发现，由磷脂酰胆碱(PC)和磷脂酰丝氨酸(PS)组成的脂质体对各种气味敏感。脂质体(PS/PC=0.2)对乙酸戊酯的敏感性远高于甲鱼和蛙类嗅觉系统。

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.