No Limits: a Little Molecule That Could

SHORT TAKES

"Life, Death, and Nitric Oxide"Anthony Butler and Rosslyn Nicholson weave a tale of how NO, a molecule once widely vilified as a dangerous pollutant, has come to be recognized as a crucial player in a range of physiological processes. Before the late 1980s, no one had seriously suggested that animals might make NO as part of normal physiology, Butler and Robinson note. Instead, the gas--thanks to its presence in car exhaust fumes--was notorious for its role in producing the photochemical smog that blanketed Los Angeles and other cities around the world. Given NO's track record, the discovery in 1987 that cells produce NO to trigger the dilation of blood vessels was initially met with great skepticism.

Since then, NO has been shown to act as a cellular messenger in a staggering range of processes, from tumor cell growth to bone depletion to cellular defense to neurotransmission to penile erection. It even causes the flashing of fireflies. How NO carries out these physiological roles--and its many others--are covered in great detail in this book.

Peppered with interesting historical tidbits and a bit of wry humor, "Life, Death, and Nitric Oxide" is meant for readers with some knowledge of both chemistry and biology. The book intersperses the inorganic redox chemistry and coordination chemistry of NO with enzymology, physiology, and medicine. Butler, a now-retired chemistry professor at the University of St. Andrews in Scotland, and Nicholson, a graduate of St. Andrews now living in Norway, manage this challenge admirably.

A chapter on catalytic converters dips into NO's redox chemistry to recount how automakers, saddled with environmental regulations limiting the release of NO into the atmosphere, modified existing catalytic converters to remove not just carbon monoxide and hydrocarbons but NO as well. In the subsequent chapter, Butler and Nicholson turn to NO's coordination chemistry to describe the defensive role NO plays in the immune system. In doing so, they explain that NO's usefulness as a defensive weapon depends on its ability to coordinate to and inhibit the activity of metalloenzymes crucial to invading microbes.

In one of the most fascinating portions of the book, Butler and Nicholson point out that NO had medical uses long before any of its physiological roles were uncovered. Chinese manuscripts, thought to date back to around 800, instruct patients suffering from angina to place potassium nitrate--which the Chinese used to make gunpowder--under the tongue. Butler and Nicholson suggest that bacteria under the tongue could convert the nitrate into nitrite. If taken into the bloodstream, nitrite breaks down into NO when it reaches the oxygen-starved cardiac arteries. Centuries later, NO-releasing drugs such as nitroglycerin (glyceryl trinitrate) and even inhaled NO gas continue to find use as vasodilators to ease cardiac pain.

This short book's only significant weakness is the somewhat haphazard organization of the topics. But this is a minor quibble, given that readers will take away from this book a rich appreciation for the varied properties of this small diatomic molecule.