@Tes yeux noirs,
nitroglycerine is taken as a pill which converts to NO and this allows dilation of blood vessesls and controls the endothelium. Taking NO is not recommended by Drs . I think it has to do with how dosage by oxiation of Nitroglycerine is better metered dosage in the vscular system . But yes NO is a medicine that helps protect against heart attck.
Theres a story about how physicians found out the relationship that nitro has with controlling blood vessel flexibility. They studied coall miners in Englnd n US for years. They noted that miners always hd heart attcks on weekends when they were off and not while they worked in the mins (theu used nitro and dynamite )