托福阅读背景资料：味觉系统调查

　　Take a deep breath. Taste anything? Actually，your lungs may. Because scientists have discoveredthat the same receptors that exist on the tongue totaste bitter substances are also found on thesmooth muscle of the lungs.

　　Researchers were studying the receptors on smooth lung muscles that regulatecontraction and relaxation¹ of theairways. That’s when they made the discovery—which was sounexpected that the researchers themselves were skeptical⁴.

　　Finally， they became convinced that the receptors were really there， though notclustered in taste buds as they are on the tongue. The scientists then exposed human andmouse airways³ to various bitter compounds to gauge⁵ the effects.

　　Many toxic⁶ compounds are bitter，so the researchers expected the lung muscle to tense upand contract—to compel the breather to move away from whatever was bitter and perhapstoxic. But， in a second surprise， bitter compounds relaxed and opened airways better thanany existing asthma⁷ drug. The study is in the journal Nature Medicine. [Deepak Deshpande etal.， “Bitter taste receptors on airway² smooth muscle bronchodilate by localized calciumsignaling and reverse obstruction”]

　　Researchers will continue to search for the role of the receptors. Meanwhile， the workrepresents a surprising new lead in the search for drugs to treat asthma， emphysema orchronic bronchitis.

　　—Cynthia Graber

 

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