Dimorpholamine

Extended term, continuous measurement and observation of drug responses were performed to examine the feasibility of a custom-made whole-body plethysmograph for measuring respiratory function in unanesthetized, unrestrained monkeys. Using this apparatus, respiratory function (respiration rate, tidal volume, and minute volume) was observed for 23 hr in unanesthetized, unrestrained cynomolgus monkeys (Macaca fascicularis). The respiration rate, tidal volume, and minute volume in the light period (7:00 to 19:00) reached approximately 30% to 50% higher values than in the dark period (19:00 to 7:00), thus clearly exhibiting circadian variation in the cynomolgus monkey respiratory functions. Administration of morphine (10 mg/kg, s.c.) resulted in sustained reduction in tidal volume and minute volume, and ketamine (30 mg/kg [sub-anesthetic dose], i.m.) also produced sustained reduction in respiration rate, tidal volume, and minute volume. With dimorpholamine (1 mg/kg, i.v.) or caffeine (10 mg/kg, s.c.), respiration rate, tidal volume, and minute volume increased. Physiological saline (1 ml/kg, s.c. and 0.1 ml/kg, i.v.) and chlorpromazine (10 mg/kg, s.c.) produced no clear-cut changes in respiration rate, tidal volume, or minute volume. From the above results, we conclude that our custom-made whole-body plethysmograph is useful for measuring respiratory function in unanesthetized and unrestrained monkeys.

A highly sensitive apparatus and method for measuring respiratory changes in conscious mice and rats is described. The apparatus is constructed from readily available components and consists of three sections: 1) mouse housing capsule and respiratory-sensitive part; 2) air supplying part; and 3) data recording part. Changes in the respiration of an encapsuled mouse can be accurately detected by means of changes in pressure exerted on the respiratory-sensitive part attached to the capsule. In our study, the rapid increases and decreases in the respiratory rates of these animals after the i.v. administration of respiratory depressing agents (morphine and arachidonate) and a respiratory stimulant (dimorpholamine) were recorded with exceptional accuracy by this procedure.