For the first time, researchers have discovered nicotine receptors on kidney cells, a further indication that smoking can accelerate kidney damage.
"There is a lot of clinical evidence with patients suggesting that people who have kidney disease and who smoke have a worse prognosis than people who don't smoke," said study co-author Dr Edgar A. Jaimes, an associate professor of medicine at the University of Miami School of Medicine. "They end up on dialysis faster. We have found one of the possible mechanisms that makes that happen."
The findings were presented Wednesday at the American Heart Association's Annual Fall Conference of the Council for High Blood Pressure Research, in San Antonio.
The kidneys regulate the body's excretion and re-absorption of water and electrolytes - such as calcium, magnesium, potassium, sodium and sulfate. If the kidneys aren't able to excrete these substances, fluid and blood volume increases. High build-ups of waste products in the blood can make a person feel sick, according to background information for the study.
Kidney disease is the most common cause of high blood pressure, Jaimes noted. Even subtle disruptions in kidney function can affect blood pressure, since the kidneys regulate levels of salt in body fluids. If kidney disease worsens, it can lead to kidney failure, requiring dialysis or a kidney transplant.
Nicotine receptors on kidney
Jaimes and his colleagues at the Miami Veterans Administration Medical Centre looked for nicotine receptors on kidney cells and found them. "They've never been described before," he said.
The receptors were found on mesangial cells, which are located in the glomeruli - the kidneys filtering units. In kidney disease, those cells are often activated to produce collagen and fibronectin, molecules that cause kidney scarring.
That's just what happened when the researchers added nicotine to cultures of kidney cells at a concentration similar to what could be expected in an average smoker. Mesangial cell proliferation increased by 50 percent to 80 percent. Fibronectin production increased by about 50 percent. Those effects were reduced when a compound blocking the nicotine receptors was added.
"This damage happens on top of everything else that smoking does," Jaimes said.
It's a finding with a practical application for doctors treating kidney disease, he said.
"The main thing for people who have kidney disease is that smoking cessation should be part of the treatment," Jaimes said. – (HealthDayNews)
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