WASHINGTON (AP) _ Nicotine given to animals in water or by injections stimulated the growth of blood vessels. The finding surprised researchers and could have implications for some medical treatments and the long-term use of nicotine patches.
``This was totally a shock to us. We expected just the opposite,'' Dr. John P. Cooke, director of vascular medicine at Stanford University School of Medicine, said in a telephone interview.
Encouraging the growth of blood vessels can be good or bad depending on circumstances, said Cooke, whose findings were reported in Friday's issue of the journal Nature Medicine.
It's beneficial in cases where a patient has circulation problems, he explained. But the process, called angiogenesis, can also result in encouraging the growth of tumors, which need blood vessels to grow, and plaque which can clog larger blood vessels, he said.
``Cardiologists are very enamored now of angiogenic therapy to treat poor blood flow to the heart, to treat poor blood flow to the legs,'' Cooke said.
But he cautioned that in this type of treatment it will be important to deliver the agents that encourage vessel growth directly to the place where needed. ``If they are given systemically it can have unwanted consequences,'' he said.
But he was quick to add that people should still use nicotine patches to stop smoking, just not for long periods.
``That is a very good therapy, nicotine patches, but they should be used as directed for a short term. Some people make the mistake of using them for a long term and that could have consequences,'' he said. ``But it's so important to stop smoking.''
Directions with the patches generally call for their use for a limited period of time.
``Our labeling is very clear that this is for a 10 week period and use beyond 10 weeks is not recommended,'' said Ken Strahs, a vice president at GlaxoSmithKline, which makes Nicoderm CQ, one of the best known brands. ``We think that this study just emphasizes the need for smokers to quit smoking as soon as they possibly can.''
Dr. Rakesh Jain of Massachusetts General Hospital and Harvard Medical School agreed that it is vital to stop smoking and the patches can be useful.
``There is no reason to panic,'' he said. ``To quit smoking, that's the best thing.''
Jain, who was not part of Cooke's team, said the results help confirm earlier studies, but more research needs to be done to better understand the effect of nicotine.
It's hard for many doctors to accept that non-smoked nicotine promotes blood-vessel growth because they are used to thinking of nicotine in connection with tobacco smoke, Cooke explained. Smoking can damage the circulation, but the effect is complicated because there are some 4,000 chemicals included in smoke, he explained.
Cooke said his researchers were surprised at finding the increased blood flow in mice after the nicotine was either injected into muscle or supplied in water.
But they were able to confirm the results in cell cultures as well as in the mice.
He said many people are surprised that artery-clogging plaques need blood, because the plaque seems inanimate. But he likened it to a coral reef, which also looks inanimate but is full of living cells.