Alteration of aminophylline-induced respiratory stimulation by perturbation of biogenic amine systems

Aminophylline-induced stimulation of respiration in halothane-anesthetized rats was abolished in rats given 6-hydroxydopamine and desmethylimipramine neonatally to selectively destroy central nervous system dopamine nerve terminals. The respiratory stimulation was also prevented by prior administration of dopamine receptor antagonists haloperidol and cisflupenthixol. The combination of apomorphine and aminophylline produced an additive stimulatory effect on respiration to values greater than those observed with either drug alone. Animals which received pargyline and 5,7-dihydroxytryptamine neonatally to selectively destroy central nervous system serotonin nerve terminals appeared to be more sensitive to the stimulatory effects of aminophylline on respiration when tested as adults. The depressant effect of 5-methoxy-N, N-dimethyl-tryptamine on respiration was slightly enhanced in the presence of aminophylline. These data suggest that the respiratory response to aminophylline is the summation of the effects of this drug on central nervous system dopamine on serotonin neuronal systems.