cardiac muscle contractile responses to six narcotic analgesics ( morphine , meperidine , pentazocine , fentanyl , methadone and l-alpha-acetylmethadol ) , at concentrations from 10 ( -8 ) to 10 ( -4 ) m , both in the presence and absence of the narcotic antagonist , naloxone , were studied in the isolated , isometric cat right ventricular papillary muscle preparation .
C0027061
cardiac muscle
C0030352
papillary muscle