DETROIT -- The gray probe, looking like a Nintendo Wii controller, is draped around Zach Zenner's neck. He puts the instrument there for maneuverability -- something he has done almost every morning since he started working with ultrasound machines earlier this year. He wants to get this right.

He spreads electrode gel on the machine’s tabletop platform and lines up the anesthetized rat he has been studying the past few days. Zenner turns the lights off and the machine on in Room LL362 of the John D. Dingell Veterans Affairs Medical Center. He can read the screen better this way.

The search begins for the animal’s aortic arch.

Sometimes, it takes him 20 minutes to locate the arch. On this day, Zenner finds it on the first try. “Oh yeah,” Zenner said, marveling at his initial perfect alignment. This saves time. It also shows the progress he has made as a volunteer research assistant for Dr. Noreen Rossi since January.

Zenner, a running back for the Detroit Lions with a potential future in medicine, is part of Rossi’s team studying the effects of glucose and fructose on hypertension and blood pressure in rats. This is one of thousands of studies conducted by the Veterans Affairs hospitals each year, one Rossi and Zenner hope will provide beneficial information for human diets.

The ultrasound is part of Zenner’s daily routine in the basement laboratory, where he derives satisfaction from small victories such as hitting the ultrasound the first time.

Zach Zenner is part of a team studying the effects of glucose and fructose on hypertension and blood pressure in rats. Michael Rothstein

“Oh, I love it when it works out,” Zenner said through a mask he wears because of the allergies he has to some animals. He eyeballs the lineup, creating a perfect match and a better picture. Then he injects the rat with a drug to raise its blood pressure, expanding the aortic arch.

The machine beeps twice. “Oh, you see it?” Zenner asked a visitor one day in March. The machine beeps twice again. The rat's blood pressure returns to normal. It’s a smaller range of expansion. This rat has been more difficult than most.

This goes on for about 45 minutes, ultrasounds on the rat's aortic arch and renal artery, watching them expand and contract because of drugs it was given. Earlier in the day, Zenner studied the rat’s reaction to drugs off curves on a computer. The ultrasounds offer visual proof.

Some medical students spend a semester learning how to perform ultrasounds. Zenner, because of this research project, picked up the skill in weeks -- something he’ll be able to apply after football when he heads to medical school.

Zenner had an odd initial introduction to anatomy: deer hunting with his father, Paul. After they shot a deer, they would remove its organs to preserve the meat and butcher the deer themselves, offering 13-year-old Zach his first exposure to internal organs. He observed the intricacies of anatomy and how organs work.

"He kicked ass in everything that he touched. His dissections were beautiful." Professor Scott Pedersen

South Dakota State University

“You plant lots of seeds, I guess, when they are a kid, and as a dad, you don’t know what’s going to stay with your kid and what’s not, right? We just did it,” Paul said. “He was interested, and we had the transparencies, and mostly because I wanted him to understand where to shoot the deer so that it was a clean kill, basically, and not a wounded animal. I had a booklet and things, and we looked at that together about where there’s only a couple of places you would want to shoot a deer, a mammal that big, so that it goes down.

“Then out in the woods, I guess, you would point stuff out to him and he was always interested in it.”

Zenner enrolled at South Dakota State five years later, the only school to offer him a Division I scholarship. Paul suggested a career in health care. Zenner had contemplated it before. He started taking classes and found something he was good at and enjoyed.

He balanced working on human cadavers in professor Scott Pedersen’s anatomy class during his junior year with rushing for over 2,000 yards for the Jackrabbits. He first took Pedersen's class as an anatomy student, but returned as an intern and then came back a third time as part of Pedersen's dissection team before graduation. The human body fascinated him, how one organ connected to another to make everything operate.

It’s been three years since Zenner worked with Pedersen, yet the professor still calls him "one of the finer mentors" he has had during his 17 years in the program. Watching Zenner in an anatomy lab and with students, Pedersen had little doubt Zenner had the skills to become a surgeon and the bedside manner to be a doctor.

"He kicked ass in everything that he touched," Pedersen said. "His dissections were beautiful. I can’t say surgeon-grade because it’s sort of a destructive process with dissecting. He was fantastic."

Zenner was accepted to the Sanford School of Medicine at the University of South Dakota, but one thing kept him from beginning his studies: the NFL.

Two Chicago defenders hit Zenner on Oct. 18, 2015, cracking multiple ribs and partially collapsing his lung. Zenner went to Henry Ford Hospital for inpatient care for a couple of days. His injuries ended his rookie year but provided an unexpected benefit.

While hospitalized, Zenner asked anyone he encountered about potential medical-research opportunities in the winter. He would have a long offseason of recovery and wanted to find something interesting to increase his knowledge and feed his passion for medicine.

Zach Zenner's rookie season was cut short due to injury, but the silver lining was it led to a medical-research opportunity. Leon Halip/Getty Images

He connected with Henry Ford Hospital's Dr. William Beierwaltes, who hired him as a volunteer research assistant in 2016. While there, Zenner worked on a project testing rats to discover how fructose affects hypertension levels. The project took months, overlapping with Lions minicamp. It also led him to Rossi. Beierwaltes recommended Zenner to her when she was seeking research assistants for her 2017 project, which also involved testing glucose and fructose levels in rats.

Rossi didn’t know Zenner played in the NFL. She knew only that a colleague she respected recommended him and he’d work for free. She hired Zenner after an initial November meeting. It’s been a good pairing.

“He’s good with people. He’s good with the rats,” Rossi said. “... Most labs do studies on rats that are asleep, and when you’re studying stress and nerve, that kind of thing, being asleep doesn’t really ... it actually alters the results. But these studies are very hard to do on awake rats, but he’s good.

“Even though he doesn’t do the surgery yet, he wants to be a surgeon. I think, just being able to do the study quietly requires ... that’s something you need as a surgeon, too, or even as a physician, that you can remain calm when things go crazy, when things go wrong.”

Zenner’s calm demeanor in high-pressure situations is beneficial in research whenever an aberration shows up in data. His bluntness led Zenner’s wife, Alyssa, to tell him recently he’d be good at any type of medicine except pediatrics. He might be too matter-of-fact for that.

Medicine is his future. Research, something he has gained a larger appreciation for, is his present.

“This fricking guy.”

Zenner shakes his head as he scans the rat he has been studying the past three days. Most rats he has observed have followed predictable patterns based on what they’ve been fed and are drinking. Not this one.

“He’s very resistant to what I’m trying to do,” Zenner said. It’s the middle of an hour-long scan of the rat during which Zenner is reading blood pressure and heart rate levels on a black desktop computer based on different drugs he’s given the rat. It’s not even 9 a.m., but Zenner, in a generic white lab coat with his identification badge hanging around his neck, has been here almost an hour in Room LL318 -- one of the rooms he has been in seven days a week during Rossi’s project.

As aberrations occur -- and with this rat, there have been a lot -- he writes notations in his composition notebook. He’ll refer to his notes later in the study when he does his charts based on the data he has compiled.

He has learned that the data is the data, meaning there are no set goals for the project. The observations unearthed could lead to new findings about hypertension, blood pressure and how both animals and humans digest fructose and glucose.

Later, as Rossi and Zenner harvest the rat’s organs for continued study, he expresses frustration with the difference in readings.

“There are variations in rats, just like they are people,” Rossi tells Zenner. “It’s next-level, though. There’s one that will aggravate you every time.”

Zenner nods. The past two years have given him an understanding of research he didn’t have as an undergraduate. He has learned from Rossi, a Yale-educated nephrologist (kidney specialist) and researcher who has practiced daily for over 20 years.

Zenner remains with the rat postmortem, dissecting other organs, just as he did in his college anatomy class and with his dad on deer-hunting trips. One day, he says, he looks forward to working with human patients, trying to save lives instead of studying animals and corpses.

There’s another byproduct of Zenner’s research. The further away he is from his undergraduate degree and the more competitive medical school and residency matching become, the more valuable these experiences will be.

Working on Rossi’s study gives Zenner the chance to be published in medical journals. Putting his name on multiple research papers while he’s still in the NFL will give him an advantage whenever he ends up in med school. Some students wait years to get published or never do research at all.

“Yeah, and I think research in general -- forget about that, in addition to all of that and getting in or whatever -- it gives you a different way of thinking about things,” Rossi said. “You don’t take things for granted. Like this is a normal rat. This is supposed to be a normal rat. It didn’t get fructose or glucose or high salt. He just got regular rat chow and water and yet it’s acting weirdly.”

Zenner doesn’t fully grasp the importance of publication yet. It’s not why he inquired about working with Rossi. He wanted to stay engaged with medicine and keep his brain active in the offseason. He could have played video games or sat on a beach. Instead, he has been in a basement every day with rats, studying dietary choices. Some of the initial findings -- he can’t say what because that information is proprietary -- have changed his own diet.

It’s just another perk for Zenner, hopeful future medical student and current NFL player and medical researcher.