NURSE JACKIE. 10:30 tonight, Showtime.

LONG BEFORE she shed Carmela Soprano's lacquered nails for the well-scrubbed cuticles of an emergency-room nurse in Showtime's "Nurse Jackie," Edie Falco was a bit of an adrenaline junkie.

"I got obsessed with [TLC's] 'Trauma: Life in the E.R.,' " Falco said at a Showtime party in Hollywood a few months ago.

"I've been watching it for years. I've lost friends over it, because they can't sit with me while I watch it," she said. "I've always loved that medical stuff. So the fact that I end up playing [a nurse], doing a show like this, is hysterical to me."

And not even a little off-putting, though in tonight's premiere, her character, who works in a New York City hospital, will encounter more blood and body parts than Carmela, at least, probably saw in the entire run of "The Sopranos."

"The medical stuff - I don't know. Some people are squeamish, and some people aren't. And I'm just not," she said.

Which is not the same as saying that Falco, whose own Aunt Carmela is a nurse, is pining for the real thing.

"The responsibility scares the s--- out of me. I don't think I'm up for that."

Truth is, even a lot of nurses might not be up for the life of Jackie, who prays, like St. Augustine, that God will make her good - "but not yet."

A work in progress on a network where moral ambiguity's the rule, not the exception, Jackie, who has problems with both men and pills, nevertheless stands out from a crowd that includes a pot-dealing mom - "Weeds" returns for a fifth season tonight - a serial killer with principles ("Dexter"), a writer with women issues ("Californication") and a king with major women issues ("The Tudors").

And not just because she quotes Augustine and T.S. Eliot.

Falco's simply magnificent in a role that exploits a certain no-nonsense quality she's always brought to even the nonsensical aspects of her characters. Carmela Soprano may have been full of it at times, but Falco gave her conviction.

There's remarkably little nonsense about Jackie, despite some extreme behavior in the pilot, which was made available to Showtime's digital subscribers before tonight. Subsequent episodes show a woman whose life's going to look all too familiar to many working mothers, even those who've managed not to complicate things to the extent Jackie has.

Executive producer Linda Wallem, who describes herself as "17 years sober," sees the character as a classic, though relatively high-functioning, addict.

"Part of being an addict is you want more," she told reporters in January, attempting to explain how Jackie can have a lover at the hospital - played by Paul Schulze, a longtime friend of Falco's who was also Carmela's pal, "Father Phil" - and a husband at home.

No such explanation seems to be required for any number of male characters, from "Rescue Me's" Tommy Gavin to Carmela's own Tony (James Gandolfini), but let's not kid ourselves that the double standard's dead.

Falco's not worried.

"Any more backlash than there was from doing a mob show for Italians, are you kidding me? I welcome this particular backlash," she joked.

The first of at least three medical series we'll see in the next year that focus on nurses, not doctors, "Nurse Jackie" shines a light, sometimes a glaring one, on the people who interact far more intimately with the sick and dying than most doctors do.

Falco, who spent a little time observing emergency-room nurses at work before deciding it felt too "obtrusive," said she saw "nothing really dramatic. I saw a lot of heart things that they thought were heart attacks, that weren't. A couple of broken bones. An inmate that had a fever . . . it was not a lot of stuff that you see" on TV.

"I really just wanted to be a fly on the wall, which I can't really be, which is why 'Trauma: Life in the E.R.' is so great. I'm alone in my room. They're not looking at me, I'm just looking at them," she said.

She's also seen urban emergency rooms from the other side.

"Back in the day, when I didn't have health insurance, something would go wrong in the middle of the night, and I'd spend hours and hours in the waiting rooms of emergency rooms of New York City," she said, recalling them as "awful, terrifying places."

Coming off "The Sopranos," she was pitched a lot of things, she said.

"Any time an Italian wife came up, I was the first person they thought of, and it's flattering, but also not very creative," she said.

Having worked only a few days a week for much of the run of "The Sopranos," she was also looking to be busier, she said.

"I work very hard when I commit myself to something and I had to make sure it was something I was really crazy about. So I said no to a lot of stuff before I said yes to this one," she said.

"As an actor, you know, waiting tables for 15 years, you never imagine you'll be in a position like this. I still have to pinch myself, you know? But this is why - I was on a television show that made a lot of money for a lot of people, you know. And the awards thing [she won three Emmys for "The Sopranos"], it's literally money in the bank . . . It does give you a certain amount of clout. But, you know, briefly, until the next thing comes along and someone else has it," she said.

For now, though, she's just trying to figure out how to describe her new show, a half-hour of highs, lows and occasional laughs.

"People say black comedy. It's very hard to categorize. Like I say to my friend as I'm working on this, 'I don't know what this thing is,' " she said.

"I'm at a loss. And my friend said, 'Well, maybe that's all right.' " *

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