Scientists studying the tiniest blood vessels found an interesting subject: reindeer noses. Turns out that Rudolph's nose is red due to "nasal microcirculation," which apparently is what gives him a big edge while hauling a heavy sleigh in the deep freeze of winter.

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Every once in a while, medical researchers hit it right on the nose, answering burning questions that plague humankind.

Scientists have recently tackled one of those, and their results were published this month on, the very respectable online journal associated with the British Medical Association. The object of their study is — what else? — the nose.

Rudolph’s, to be precise. And why, scientifically speaking, it’s so red.

Turns out there are good reasons to look at Rudolph’s superior “nasal microcirculation,” which apparently is what gives him a big edge when flying through cold winter air hauling a heavy sleigh.

Professor Can Ince of the Department of Intensive Care Medicine at Erasmus Medical Center in Rotterdam, Netherlands, with colleagues there and in Norway, found that reindeer have very richly vascularized noses.

It’s those flowing red blood cells in hairpinlike capillaries — 25 percent more than in the humans they studied — that keep Rudolph’s nose from freezing, regulate the temperature of his brain, and allow him to cool off when he overheats.

“These factors explain why the nose of Rudolph, the lead flying reindeer employed by Santa Claus to pull his sleigh, is red and well adapted to carrying out his duties in extreme temperatures,” the authors wrote of the famous reindeer’s “luminous red nose.”

Why study reindeer? In part because the researchers figured their work would be a natural for the BMJ’s much read Christmas issue. And, more seriously, because it was a good way for Ince to test his work in developing handheld video microscopy — devices he’s developing for use at the bedside in critical care medicine.

Allegedly, researchers were testing their hypothesis that Rudolph’s nose is red because of the presence of this highly dense and rich nasal microcirculation.

A video released with the paper shows researchers in Norway leading a placid reindeer into the lab, where it obligingly marches along on a treadmill as they record the blood flow in its big, furry nose.

Other pictures show how the microcirculation looks when viewed with Ince’s instruments.

In humans, Ince said in emails, similarly measuring the blood flow in tiny blood vessels can deliver important medical information, particularly in patients with sepsis (blood infection) or heart failure.

Our noses, like Rudolph’s, have an important role: They help heat, filter and humidify inhaled air, control inflammation, transport fluid to form mucus and deliver oxygen to nasal cells, the authors wrote.

Those nasal tissues also play an important role in the uptake of drugs and responses to allergens.

But studies have been hampered by not having good techniques, and most information has come from excised tissues, the researchers said.

Handheld imaging instruments have been able to show microcirculation in the nose to be the most sensitive blood-related indicator of outcome and response to treatment, the authors wrote, and have identified it as a key factor in a wide range of diseases, including treatment responses in cancer therapies.

“This has given us much insight into the origin of disease and therapy as occurring at the cellular level,” Ince said.

As for Rudolph, the researchers say they’ve solved the mystery, highlighting the “intrinsic physiological properties” of his legendary schnozz.

“We thank Santa Claus for his enthusiastic support,” they concluded in the paper. “He was as keen as us to unravel the mystery of his friend’s nose.”

Carol M. Ostrom: 206-464-2249 or

On Twitter @costrom.