Tributes have been pouring in for

Brittany Murphy

, 32, who died Sunday of cardiac arrest in Los Angeles. So have rumors, innuendos, and queries: How did the actress, who had been dogged by reports of drug use, die?

"It appears to be natural," L.A. County assistant chief coroner Ed Winter said yesterday. An autopsy was scheduled for yesterday, but results of toxicology tests may take weeks.

A heart attack doesn't seem so far-fetched: In '01, Murphy revealed that she had struggled with an unspecified heart condition since childhood.

But drug rumors are proliferating. Celeb blogger and would-be celeb Perez Hilton writes that anon "pals" insist Murphy was hooked on narcotic painkillers. Her death, he said, "comes as no surprise! We, and those who knew Brittany . . . saw this coming," adding "that does not make this any less horrible." Murphy is survived by her husband, screenwriter Simon Monjack.

And more reactions

Friends, colleagues, fans, even an ex-boyfriend have expressed messages of sorrow over

Brittany Murphy

's untimely death at age 32 of a heart attack.

Her death seems all the sadder, given Murphy's desire to have a baby. "As far as having a New Year's resolution," the 8 Mile and Clueless star told Access Hollywood on Dec. 3, "I'd love to have a child next year."

Murphy's father, reputed mobster Angelo Bertolotti, said he had lost touch with the actress for years and was stunned at news of her death: "She was just an absolute doll since she was born. . . . Everybody loved her. . . . She was just a regular gal."

Murphy, whose parents split up when she was 2, was raised by her mum, Sharon Murphy, in Edison, N.J. The actress credited her mum with her drive to achieve stardom.

"I was really grateful to have grown up in an environment that was conducive to creating and didn't stifle any of that," Murphy said.

Friends are in shock. Murphy friend and former stylist Tiffany Saidnia tells Life & Style, "Brittany was such a sweetheart, I'm deeply saddened about this." Former beau Ashton Kutcher tweeted Sunday, "2day the world lost a little piece of sunshine. . . . My deepest condolences go out 2 Brittany's family, her husband, & her amazing mother Sharon."

A funeral date has yet to be announced.

It's all over for Underwood!

Sorry, ye country-loving would-be lotharios:

Carrie Underwood

, 29, has officially removed herself from the field. The

American Idol

goddess has said yes to her paramour, Canadian hockey player

Mike Fisher

, 26, whom she has been dating for a year, says E!Online.

Carrie declares her love for MF in the liner notes to her CD, Play On: "You are the most amazing addition to my life. I thank God for you every day."

Bad news for Michael Jackson fans

A heavily publicized tribute concert honoring King of Pop

Michael Jackson

has been canceled because organizer World Awards Media GmbH has gone out of business. The show, which was to star A-listers including

Mary J. Blige

and

Chris Brown

, was originally planned for Vienna, but moved to London when some acts backed out. Meanwhile, TMZ claims the release of Jackson's FBI files will be delayed. The 333-page document, which includes notes pertaining to MJ's 1993 and 2004 molestation cases, was due to come out yesterday.

The FBI has yet to comment.

Tila Tequila lends a helping hand

Singapore-born celeb-culture byproduct

Tila Tequila

(née

Tila Nguyen

), 28, Tweeted on Sunday that she has agreed to be a surrogate mother for her brother and his wife: "That is my xmas present to them. Im pregnant!!!!"

TT has not released any details: Is she carrying their child as a gestational surrogate, or is she having her own biological child?

The publicity-lusting beauty's claims to fame include MTV disaster A Shot at Love With Tila Tequila, Fuse TV's Pants-Off Dance-Off, and photos in Penthouse, Stuff, and Maxim.

Howard Stern has a teeny fit

Howard Stern

, 55, is threatening to quit Sirius XM Radio. But don't freak out: The schlock jock is probably just angling for more dough.

Stern is about to begin negotiations with Sirius now that he's entering the last year of his ludicrously lucrative $500 mil five-year contract. It's all good, says Sirius CEO Mel Karmazin, who says he wants to keep Stern. But given cuts at Sirius and other media outlets, the abrasive deejay may have to settle for less cash. And that, folks, might make him screech and cry even more.

Britney Spears clears the record

The nation's least sensual sex symbol,

Britney Spears

, yesterday posted a list of the 75 most lyingest news reports about her (

). Her manager

Adam Leber

says the lies were culled from the more than 13,000 stories about Britney in '09. (She's so popular!)

So what's the No. 1 stupidest story? A report that Brit was dating Indian choreographer Sandip Soparrkar. (Yawn!)

No. 2 is even more boring . . .

Another Kidman challenge

Beatific

Tom Cruise

escapee

Nicole Kidman

wants to assay yet another challenging role: that of a transsexual. She tells USA Today she hankers to star in

The Danish Girl

as a post-op transsexual married to

Gwyneth Paltrow

. (

Oh my!

) Says NK: "If that story comes together, I will definitely make that story. It's an unusual story and it's a love story that needs to be told." She's very

storied

, Nic.

Be a Coen Bros. star!

The Coen Brothers

(

Miller's Crossing

) need a genuine gal to star in their remake of the '69

John Wayne

classic

True Grit

. The bros need a 12-to-16-year-old actress to play Mattie Ross (

Kim Darby

in the original). For information about sending audition videos, visit

.

Tidbits 'n' pieces

Perez Hilton

, citing anon sources, says that after

Madonna

split from

Guy Ritchie

, she mounted a campaign (well, a dinner date) to harpoon

George Clooney

as an amorous partner. The source said George felt no chemistry and couldn't "wait to get out of there."

Variety says James Cameron's gazillion-dollar Saturday-morning cartoon Avatar made $77.3 mil over the weekend to become the best-ever December debut.

Contact "SideShow" at sideshow@phillynews.com.

This column contains information from Inquirer wire services.