Image of bitter melon.
The substances that give foods such as kale and bitter melon their bitter flavor also act to reverse bronchodilation, according to research in the open access journal PLOS Biology.
In the last few years, scientists have discovered that bitter taste receptors are present in many other cells throughout the body, including smooth muscle cells in the airway, where they act to relax the cells when exposed to bitter-tasting substances.
Like most receptors, bitter taste receptors span the plasma membrane of the cell, according to researchers. When the receptor detects a bitter compound, the receptor releases a G-protein, which then splits into two parts: a G alpha subunit and G beta-gamma dimer. Investigators believe the latter acts to close the calcium channels on the plasma membrane, returning calcium level to normal and relaxing the cells.