the effects of intravenous injections of alfentanil , fentanyl , phenoperidine or morphine on respiratory and peak inspiratory air flow rate , the diaphragm electromyogram ( emg ) , the activity recorded extracellularly from respiratory neurones located in the ventral respiratory group and the cardiovascular system were examined in anaesthetized rats .
C0002026
alfentanil
C0015846
fentanyl