The spider is the Brazilian wandering spider (Phoneutria nigriventer). Bites from that spider are intensely painful and "can cause priapism, a potentially harmful and painful erection that can last for many hours and lead to impotence," states an American Heart Association news release.
Researchers from Brazil and the Medical College of Georgia purified a toxin from that spider's venom and tested it in rats and mice.
The researchers found that the toxin causes a chemical chain reaction that sets the stage for better blood flow in penile tissue -- and that could help treat ED.
"This toxin could be important for development of new agents for treatment of ED," write the researchers, who included Kenia Nunes, PhD, of the Medical College of Georgia in Augusta.