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Lifetime's "Strong Medicine (search)" was originally created to be "about women on both sides of the stethoscope," said executive producer Tammy Ader.

So why, then, is cable's longest-running original drama beginning its sixth season on Sunday (8 p.m. EDT) with the arrival of Rick Schroder (search) as Dr. Dylan West to partner with Dr. Luisa Delgado (Rosa Blasi-Finn)?

"For ages, my own OBGYN, who's a man, has being saying it can't be just women who treat women," Ader said, "and we've always wanted the other partner to be 180 degrees different from Rosa's character."

Delgado's an outspoken single mom, who champions the issues of the underprivileged. Harvard educated Dr. Dana Stowe (Janine Turner) was her partner until the middle of season three; former Army officer Dr. Andy Campbell (Patricia Richardson) then co-ran the Philadelphia-based clinic until the end of last season.

Contemplating what new lead character might provide similar culture-clashing chemistry, Ader realized the true 180-degree difference was a man.

West's arrival is, Schroder said, clearly "a shock" when he's "introduced in the ER in the middle of a tragedy — a train derailment with a lot of injured people." Delgado in particular is "not too happy" because back in medical school, when he was chief surgical resident and she was an intern, they were often at odds.

Schroder, now 35, won a Golden Globe as the weeping blond kid in the 1979 remake of the boxing melodrama "The Champ (search)." During his 'tween and teen years, he starred as rich and spoiled Ricky Stratton in the sitcom "Silver Spoons (search)." In 1989, he co-starred in the Western miniseries "Lonesome Dove (search)." And from 1998 to 2001, he was troubled Detective Danny Sorenson on "NYPD Blue."

Wanting to present him with a different sort of challenge from the intense, unhappy Sorenson, Ader created West as a much sunnier, more laid-back personality, a single guy with a great sense of humor. She then flew to Phoenix, where Schroder and wife Andrea are raising their four children.

"It's nice to be wanted," said Schroder, whose character is "a San Diego beach guy" but "very committed and very enthusiastic toward his job."

Brooklyn-born Schroder's similar attitude about his own work probably helps explain his successful transition from child stardom to a solid adult career that is balanced with a devotion to family and lack of interest in Hollywood hype.

"I love what I do and I bring a great deal of enthusiasm to anything I do. I think there's a perseverance that wins over talent. I have a lot of perseverance, though I do have some talent," he said, talking between scenes on the "Strong Medicine" set.

One of the reasons Schroder signed on, too, was that his deal also allows him to direct upcoming episodes of the series and — when the right project is found — a Lifetime movie.

The actor has taken an interest in behind-the-camera work of late. He wrote, directed and produced the independent feature "Black Cloud (search)," a story about a young American Indian boxer. He also won Country Music Television's 2004 director of the year award for the video "Whiskey Lullaby," sung by Brad Paisley and Alison Krauss.

But on this morning, Schroder was very much the actor, doing a lengthy walk-and-talk scene with Blasi-Finn for an episode titled "Dying Inside." They move down the hospital's crowded corridors while discussing a difficult diagnosis and sparring over class and cultural issues.

Schroder looks comfortable in his white medical coat, but is still finding it challenging "to say all these large medical words understandably and at the same time have all the energy that you need."

But fitting into a long-running show is something he's had prior experience with from his stint on "NYPD Blue."

"It's kind of like you are joining a new pack, a wolf pack, a dog pack. You've got to proceed with caution, somewhat tentatively ...," he said.

Everyone is sort of on their best behavior for the first few weeks, but then people start letting that down to show who they really are," he said, grinning. "But it's a great group of people. They have made me feel very welcome."