Tuesday, 31 July 2012

Famous Dreamers - Otto Loewi's Novel Prize Winning 'Acetylcholine' Dream

Otto Loewi (1873-1961), a German-born pharmacologist and physiologist, won the Nobel Prize for medicine in 1936 for his work on the chemical transmission of nerve impulses and the discovery of acetylcholine. In 1903, he accepted an appointment at the University of Graz in Austria, where he would remain until being forced out of the country in 1938. In 1905 he received Austrian citizenship.

In 1903, Loewi argued against common held scientific belief, that nervous impulses were the result of electrical transmissions. Loewi hypothesised that chemical transmissions were more likely the mode but had no idea how to prove it. He eventually put the idea on the back burner until 17 years later in 1923, after he had the following dream:

The night before Easter Sunday of that year I awoke, turned on the light, and jotted down a few notes on a tiny slip of paper. Then I fell asleep again. It occurred to me at 6 o'clock in the morning that during the night I had written down something most important, but I was unable to decipher the scrawl. The next night, at 3 o'clock, the idea returned. It was the design of an experiment to determine whether or not the hypothesis of chemical transmission that I had uttered 17 years ago was correct. I got up immediately, went to the laboratory, and performed a single experiment on a frog's heart according to the nocturnal design.

Loewi believed that the experiment shown to him in his dream would prove once and for all that transmission of nerve impulses was chemical, not electrical. The day following the first forgotten version of the dream, he said, was ‘the longest day of his life’ as he could not remember his vital dream. Before Loewi's experiments, it was unclear whether signalling across the synapse was bioelectrical or chemical. Loewi's famous experiment, published in 1921, largely answered this question. According to Loewi, the  key idea for his experiment was revealed in the dream. He dissected out of frogs two beating hearts: one with the vagus nerve which controls heart rate attached, the other heart on its own. Both hearts were bathed in a saline solution (i.e. Ringer's solution). By electrically stimulating the vagus nerve, Loewi made the first heart beat slower. Then, Loewi took some of the liquid bathing the first heart and applied it to the second heart. The application of the liquid made the second heart also beat slower, proving that some soluble chemical released by the vagus nerve was controlling the heart rate. He called the unknown chemical ‘vagusstoff’. It was later found that this chemical corresponded to acetylcholine

Even though Dr Loewi had established highly significant probability that his hypothesis was correct, it took the scientific community a further 10 years to accept his outcomes. His dream and subsequent diligence gave rise to the theory of chemical transmission of the nervous impulse and he was awarded a Nobel Prize. 

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