The Spark of Life by Frances Ashcroft: review - Telegraph
The Spark of Life by Frances Ashcroft: review
Helen Brown admires The Spark of Life by Frances Ashcroft, which brings cellular biology to life.
Learn how lightning kills in Frances Ashcroft's new book Photo: © Corbis RF / Alamy
By Helen Brown
5:06PM BST 28 Jun 2012
We’re all familiar with the hospital drama scene in which the regular beeping of a heart monitor stops. Somebody yells “Cardiac arrest!” Somebody else, brandishing the defibrillator paddles, yells “Clear!” The patient jerks violently as the electricity delivers a life-restoring jolt through the chest and, after a suitably tense pause, the heart monitor begins to beep again.
The non-medical viewers among us seldom give much thought to what’s actually going on here. But – as Frances Ashcroft explains in her fascinating new book on the wonders of bioelectricity – the televised ER scene is far from accurate. For a start, the electric shock is unlikely to cause the patient to jerk. But, more importantly, the Frankensteinian impression of that shock reanimating the heart is entirely misleading. Defibrillators are not used when the heart has stopped, but when it is “fibrillating”: when the ventricles are beating so asynchronously that the organ is reduced to a twitching mass of flesh, unable to pump blood.
It is not the heart which has “arrested” but the blood flow. The electric shock from the defibrillator does not restart the heart. It stops it in the hope that the stopped heart will spontaneously restart itself at a normal rhythm.
What’s far more amazing than our high-voltage medical technology, though, is the fact that we are all constantly powered by electricity. We are – in Ashcroft’s words – “electrical machines”. In lively, conversational prose – refreshingly accessible to any lay reader prepared to make a little effort – the Oxford professor of physiology describes how the movement of electrically charged atoms (ions) carry currents across cell membranes and around our bodies to keep our nerves and muscles functioning. Maintaining the fine balance of positively charged sodium, potassium, calcium and hydrogen ions and negatively charged chloride ions within our bodies costs us about a third of the oxygen we breathe and half of the food we eat.
Although the electricity you make travels through your nervous system at only 0.07 miles per second (compared with the 186 million miles per second that electrical signals travel through the wires of your kettle), the brain you are using to make sense of this article requires 10 per cent of the oxygen you’re breathing just to drive its sodium pump.
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An expert on the channels through which our ions move, Ashcroft is one of the few, lucky scientists to have seen her research lead to clinical practice. Back in 1984, she discovered a tiny pore through which potassium ions leave cells and observed that this channel was closed by the breakdown of glucose, triggering insulin secretion. By the mid Nineties, her team had determined the DNA sequence that codes for the potassium ion channel and the gene mutation that causes a significant increase in the risk of type 2 diabetes. Specifically, her work has already caused a change in the treatment of 90 per cent of patients with neonatal diabetes that has improved their glucose control and quality of life.
The thought of what she has achieved, she writes humbly, “still sends excitement fizzing through my veins”. And she’s passionate about sharing that fizz with her readers, leading us through the bizarre history of bioelectrical discovery.
We learn of small children suspended in mid-air by cords of insulating silk and charged up by rapidly rotating balls of sulphur. Of the visible nerves of squid and the irritating, late-18th-century shortage of experiment-ready frogs after Luigi Galvani first hypothesised that an electrical spark could stimulate their leg muscles to shorten. There’s an extraordinary description of how, when European scientists went to South America in 1799 in quest of electric eels, the locals drove their horses into the Orinoco until their terrified stamping and thrashing caused the eels to rise to the surface and attack until some of the horses were dead and the eels so exhausted that they could be safely captured.
We learn how lightning kills, why sharks bite power cables and how the poison of the puffer fish (like many other natural toxins) works by blocking sodium ion channels of the nerves and skeletal muscles: you die when this paralyses your respiratory muscles, although as your heart has a different type of sodium channel so keeps beating and, (horrifyingly) as the poison doesn’t cross the blood-brain barrier, you stay conscious to the last. It is typical of the ever-engaged Ashcroft to have tried eating puffer fish herself: “I found it rather insipid: it was the spice of danger that enlivened the fish.”
Until I read this positively charged little book, I’d always thought of cellular biology as a kind of clever, chemical gloop, but Ashcroft really brings home the importance of the animating spark in the soup.
The Spark of Life
by Frances Ashcroft
352pp, Allen Lane t £18 (PLUS £1.35 p&p) Telegraph Books (RRP £20, ebook £20)
