By Adam Marcus

TUESDAY, March 21 (HealthSCOUT) -- A family of diabetes drugs that improves the body?s sensitivity to insulin may also shield blood vessels from damage caused by hardening of the arteries and procedures to clear blockages.

A report in the current issue of the journal Circulation shows that a group of drugs called glitazones prevents lesions from forming in the smooth muscle just beneath the surface of arteries. Glitazones include Avandia, Actos and the controversial drug Rezulin.

Experts say the drugs could help patients with Type II diabetes avoid potentially fatal vessel problems. Heart and vessel diseases are the leading causes of death for the 15 million Americans who suffer from the blood sugar condition.

The finding involves a protein receptor molecule called peroxisome proliferator-activated receptor-gamma, mercifully shortened to PPAR-gamma. This molecule is found in a number of tissues, but particularly in skeletal muscle and fat cells, where it is involved in the conversion of blood sugar to energy.

More of a mystery, however, is why PPAR-gamma exists in other cells not central to blood sugar. Recent studies have pointed to a role for the protein in artery walls, but how big a part hasn?t been known.

In the latest finding, Ronald Law, an assistant professor of medicine at the University of California at Los Angeles, and his colleagues used a variety of cell-screening techniques to show that PPAR-gamma was indeed common in the smooth muscle cells of both rat, and then human, blood vessels.

The researchers then treated cells with Avandia and Rezulin (rosiglitazone and troglitazone) and an experimental compound. Not only did the drugs prevent the muscle cells from multiplying, Law says, but they appeared to hamper their ability to migrate, too.

When a blood vessel becomes diseased, immune cells flock to the affected area and burrow beneath the surface into the smooth muscle cells below. This response, initially helpful, eventually triggers a two-step reaction that leads to even greater damage.

Almost like a tumor, the interior muscle cells begin to divide rampantly, building up a mass, known as plaque, that can narrow the vessel and shut down blood flow. And they begin to migrate to the area of distress, exacerbating the problem.

A similar chain reaction often occurs in patients who receive vessel-widening treatments like angioplasty or stenting. The treated vessel can form a new plaque, which can break off and cause a stroke.

"Administration of [glitizones] prior to intervention should reduce injury, and may slow the progression of atherosclerosis," Law says.

Mounting evidence suggests that much of the vessel damage in Type II diabetics -- who have twice to four times the normal risk of vessel disease -- is due to insulin insensitivity. So the drugs could also protect patients in the beginning stages of diabetes, Law adds.

But glitazones have met with their share of controversy lately. Earlier this month, the consumer group Public Citizen petitioned regulators to revise the drugs? warning labels to reflect what it saw as a significant risk of heart disease.

The group was particularly critical of Rezulin, which has been linked to nearly 60 liver-related deaths and 56 cases of heart failure since its introduction 18 months ago. (From HealthSCOUT )