NORMAN, Okla. - Troubles continue to mount for the University of Oklahoma wrestling team as senior Nate Parker, fifth in the NCAA tournament last season, has left the Sooner squad.     Parker was moved from 141 to 149 two weeks ago in order to get freshman Teyon Ware in the lineup. Parker had a pin in his first match at 149, then lost four of five and left the team last Saturday in California between OU dual wins over Fresno State and Cal Poly.     "Nate Parker, by mutual agreement, is no longer with the University of Oklahoma wrestling program," coach Jack Spates said Tuesday. "We lost the Arizona State dual because Nate head butted his opponent and was disqualified. We have no interest in commenting on the situation."     Spates was in West Palm Beach, Fla., Tuesday to be with his father, Bob, who suffered a heart attack.     "He is fine," Jack Spates said of his father. "This is a bad year for heart attacks in the Spates family."     Jack Spates sustained a heart attack in early December, but rejoined the team a week later.     Matt Grice, who has been sidelined after shoulder surgery, or Danny Rubenstein will move into the 149-pound slot. Grice was 3-3 before the injury and hasn't wrestled since Nov. 16. Rubenstein is 2-3 and hasn't seen action since Nov. 24.     Parker finished his senior season at 14-8 after beginning the season ranked in the top five in the nation at 141. Unbeaten heavyweight Leonce Crump, ranked second nationally, is ineligible and hasn't wrestled since Dec. 8.     OU, which has slipped to 12th in the latest ratings, wrestles West Virginia on Saturday in the first round of the National Duals in Columbus, Ohio.