Just this week, news broke that Nate Dogg's estate was on the hook for nearly $300K in medical bills, raked up during the last years of his life, after a judge ruled in favor of a California treatment center.

According to TMZ, one of the late singer's associates is saying all the Nate's rap friends have refused to pitch in ... and he's left holding the bag.

Nate Dogg's estate and label owner/manager David Michery have been sued by CareMeridian in Orange County, California for unpaid bills the singer owes for treatment he received from 2008 to 2010, after suffering a massive stroke that left his partially paralyzed.

According to Michery, he vouched for the bill in 2010, but only because of nobody else would, including "Nate's so-called rapper friends."

He tells TMZ that Nate's life was hanging in the balance, and he was the only one who came forward to get the help the singer needed.

"I was the only person who would come forward because I didn't want him to die," said Michery. "Me and Nate have 20 years history together and I did what everyone should have done and tried to save his life ... not let him get kicked out in the streets and die."

Longtime Nate collaborator/friend, Warren G, echoed a similar statement, saying he did what he could ... and even made calls to no avail.

"I rode with Nate 'til the end ... I did what I could do for him with other things financially," Warren G told TMZ. "If I was able to pay for his hospital bill, I would have. I made several calls to numerous people for help. I love Nate ... he's my brother."

Who pays back the bill? Well, Michery says he intends to. He says he will release some never-before-heard Nate Dogg tracks in an attempt to earn the money he's been ordered to pay.