Supermarkets, pharmacies and small shops opened for the first time in 10 days Wednesday as a nationwide strike aimed at toppling Gen. Manuel Antonio Noriega began to fall apart. Despite the defections, Alberto Boyd, president of the National Council of Private Enterprise, said he and other strike leaders were not ending their effort to get rid of Noriega. In Washington, the Reagan administration said it was considering new sanctions to force out Noriega, but it appeared no action was imminent. The reopening of the capital's Gago, Rey and Super 99 supermarkets signaled the first crack in a work stoppage that closed an estimated 90 percent of the nation's business and industry. Later, the city's leading pharmacies reopened, as did some small clothing and other dry goods stores in the central business district. Traffic, extremely light for days, began to build again on Panama City's streets, with the usual jams of buses, taxis and private autos developing at major intersections. Grocery stores were doing a brisk but not extraordinarily heavy business. Customers were required to pay in cash and appeared to be buying mostly essentials. The government said some of the nation's banks, closed since March 3, would reopen Thursday, but only to process old checks. Even with a limited reopening of banks and some stores, there appeared to be no hope of a quick infusion of cash that would permit a return to normal commerce in the money-short nation. The cash crisis is due in part to U.S. economic sanctions against Noriega, who is charged in the United States with drug trafficking. As chief of the 15,000-member Defense Forces, Noriega is the real power behind Panama's civilian government. Some U.S. companies, including Miami-based Eastern Airlines and Harrison, N.Y.-based Texaco, Inc., this week paid the government $5 million owed for taxes, a diplomatic source who spoke on condition of anonymity said Wednesday. Owners of the reopened grocery stores could not be reached for comment, but Angelica Guinard, a leader of the opposition National Civic Crusade leader, said they had been under strong government pressure to reopen. She said the pressure included threats of confiscation of their goods and personal threats against themselves and their families. However, an executive of the Gago supermarket chain, the city's largest, said his company's stores opened ``because we have to pay our employees, and if we didn't open, we wouldn't have anything to do it with.'' He spoke on condition of anonymity. A woman leaving a Rey supermarket in one of Panama City's middle-class neighborhoods said she had bought only essentials: rice, milk, beans and soap. ``The kids don't understand,'' she said. ``They want to know why we don't have the kinds of things we had before.'' But she said the eldest, who turned 8 on Saturday, is catching on. ``He said, `Mommy, you can't throw a party for me because Noriega won't leave,''' she said. She wouldn't give her name. Felix Navarro, a wholesale fruit and vegetable dealer who closed down his own business in the strike, carefully studied prices on five-pound bags of rice before choosing one. Pointing to the rice and a container of cooking oil, he said, ``I had $100 in cash at the beginning of the month, and after I buy these, I'm broke.'' Panama's chronic cash shortage worsened last month when Noriega fired President Eric Arturo Delvalle, touching off a panic run on the banks that eventually forced their closure. The United States aggravated the crisis by imposing a number of economic sanctions, including the freezing of millions of dollars in Panamanian government funds held by U.S. banks. The Reagan administration continues to recognize Delvalle, who is in hiding, as Panama's president. White House spokesman Marlin Fitzwater told reporters in Washington on Wednesday that ``other sanctions are being actively considered'' to force Noriega's ouster. Sen. Alfonse M. D'Amato, R-N.Y., said Noriega's troops have harassed and beaten Panama Canal employees. ``There is a continuing pattern of escalation'' in Panamanian actions against the canal, he said in an interview on ABC-TV's ``Good Morning America.'' He did not elaborate. On Tuesday, Noriega condemned the presence of the U.S. helicopter carrier Okinawa on the Pacific end of the Panama Canal. It passed through the canal Tuesday on its way to its home port, San Diego. The U.S. Defense Department said in Washington that the passage was ``routine,'' but Noriega called it ``a threat and an aggression.'' There was no immediate indication how long the vessel would stay in the area.