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Bitter Pill

By Richard P. Grant Bitter Pill 3d4medical / photo researchers inc. The paper D.A. Deshpande et al., “Bitter taste receptors on airway smooth muscle bronchodilate by localized calcium signaling and reverse obstruction,” Nat Med, 16:1299-304, 2010. Free F1000 Evaluation The finding Stephen Liggett and colleagues at the University of Maryland School of Medicine set out to identify the G-protein coupled receptors (GPCRs) involved in the cont

By | March 1, 2011

Bitter Pill

3d4medical / photo researchers inc.

The paper

D.A. Deshpande et al., “Bitter taste receptors on airway smooth muscle bronchodilate by localized calcium signaling and reverse obstruction,” Nat Med, 16:1299-304, 2010. Free F1000 Evaluation

The finding

Stephen Liggett and colleagues at the University of Maryland School of Medicine set out to identify the G-protein coupled receptors (GPCRs) involved in the contraction of bronchial airway muscles that can lead to asthma. They discovered bitter taste receptors—previously only found on the tongue—on airway smooth muscle (ASM) cells, and showed that their activation causes bronchial relaxation instead.

The surprise

Liggett thought these receptors might protect against inhaled toxic substances. When his lab treated ASM cells with bitter-tasting compounds, such as saccharin or chloroquine, they saw an increase in intracellular calcium concentration—a hallmark of smooth muscle contraction, and thus presumably of bronchoconstriction. “We were thinking we’d found the cause of occupational asthma,” Liggett says. Surprisingly, when they tested the bitter substances on surgical tissue explants, they saw the muscles relax.

The relaxation

The bitter-tasting molecules very rapidly activated highly localized stores of calcium, rather than the slower, cell-wide calcium release that causes constriction. The team repeated the test in live mice, and saw the same result. “It was like nothing we had ever seen before,” Liggett says.

The drugs

There are “10,000 or more” known activators of bitter taste receptors, some of which are already used in medicine. The only issue would be making them more palatable, but that doesn’t bother Liggett much. “We’ve got more compounds than we can study,” he says.

F1000 evaluators: J. Martin (McGill Univ) E. Schneider & P. Murphy (NIAID) B. Nilius (KU Leuven)A. Morris & D. Spina (King’s Col London)

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Comments

Avatar of: John Dos Santos

John Dos Santos

Posts: 9

March 22, 2011

I was confused when saccharin was mentioned as a bitter compound used in this experiment... wikipedia tells me that it can have a bitter aftertaste, particularly at high concentrations.\n(wikipedia also tells me that saccharin has been de-listed as a potential human carcinogen)\n\nRegardless, I find this discovery to be a very interesting potentially new therapy for asthma (rapid brochodilation).\nCurrent bronchodilators (B-agonists, anticholinergics) used at high doses can have negative systemic effects.\nIf one could successfully use a substance that has no systemic effects to relieve asthma symptoms, I think that would be ideal. Especially something as "sweet" as saccharin!
Avatar of: Jan-Olof Flink

Jan-Olof Flink

Posts: 4

March 23, 2011

Very promising indeed, if perhaps an inhalator with a bitter tasting but otherwise inert compound could be used as a treatment.
Avatar of: Jan-Olof Flink

Jan-Olof Flink

Posts: 4

March 23, 2011

Bile and the acids in your stomach are quite bitter tasting.\n\nCould this be a reaction to widen up the throat and the airways when a person vomits so that nothing gets stuck and block them?

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