Transport mechanism of urate in humans

Published on May 31, 2016   52 min

A selection of talks on Gastroenterology & Nephrology

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Hello, my name is Hiroyuki Saturai, professor of pharacology, Kyorin University School of Medicine, Tokyo, Japan. Today, I'd like to discuss urate transport in our body. I will try hard to explain physiological principles of urate transport so that my talk is applicable not only to urate, but also to many negatively charged xenobiotics or endogenous substrate.
So this is the agenda for this talk. I will briefly discuss about what urate is doing in our body. Then we move to the physiology of trans-epithelial movement of the solute. Then I will come back to urate handling and especially in the two key organs in urate metabolism, kidney and the intestine. Then I will finish with drugs that affect urate transport, either a treatment or a side effect.
This is the yin and yang of urate, so good and bad of urate. If your uric acid is very high, many doctors think that you are in trouble such as gout, or arthritis, kidney stones. However, urate itself is a major antioxidant. This is a bright side. Some people say that once humans could retain urate in their body, vitamin C, also known as a very strong anti-oxidant, we lost an anti-oxidant possibly at that time when we got urate. But superoxide is generated through urate production by xanthine oxidase. And this free radical, superoxide, causes lots of trouble. It appears that radical damage and the anti-oxidant effect of urate canceled out. But other chemical dioxide dark side still remains. So here, the most problematic of the urate is its poor solubility. When urate becomes insoluble, that forms crystal. And then crystal is in the kidney that causes kidney stones. And then if the crystal forms in your joint, that activates innate immunity then leads to inflammation. And this is a gouty attack.