Johnny Nitro, whose real name was John Newton, grew up in Sacramento, the oldest of four children. When he was 13, he saved his lunch money and bought his first guitar from a pawn shop, teaching himself to play by listening to friends' B.B. King records.

A scholarship to the San Francisco Art Institute brought him to North Beach in the 1970s, and, since then, he rarely left. He lived for a while in a 1947 panel truck and worked as a car mechanic to make ends meet.

For a short time, he worked at Sears Point and other raceways. "I was the guy who mixed the fuel, so I was Nitro Man," he told The Chronicle in 2006, explaining the origins of his stage name.

Johnny performed with stars such as Albert Collins, Albert King, Tommy Castro, Freddie Roulette, and others and released several albums. Collins covered one of Mr. Nitro's original songs, "Dirty Dishes."

Like most blues artists, Johnny loved to tell a good story. Onstage at the Saloon, he'd chat with the audience, flirt with women, tell jokes and keep the crowd - which typically included local regulars and tourists from around the world - dancing all night. "His presence onstage was irresistible," Futoshi Morioka, a San Francisco guitarist said. "He could just stand there holding his guitar but had so much charisma." Among Johnny's favorite quips, said Kathy Tejcka of Benicia, who played keyboard for the Doorslammers, was this: "Keep drinking triples till you're seeing double, feeling single and getting in trouble."

Johnny himself quit drinking and smoking several years ago, his friends said. "He was really proud of that. He knew what it was like to have a second chance," Tejcka said. "He just referred to those years as 'back when I was really sick.' "

Johnny, 59, had been suffering from heart disease and diabetes for several years. At one point, he collapsed onstage and was hospitalized for several days but was back performing the next weekend, said Burton Winn of San Anselmo, the bassist for Mr. Nitro's band, the Doorslammers.

Despite his health problems, Johnny was among the most tireless musicians in the Bay Area, his friends and colleagues said. He played several nights a week, taught at the Blue Bear School of Music at Fort Mason and mentored dozens of younger musicians. "I'm 10 years younger than him, and he would wear my ass out," said Tejcka. "He rocked."