Effect of Atropine on Pigeon Pancreas II

It is well established that atropine administration results in decreased pancreatic secretion; however, little information has been available concerning the metabolic effects of this agent on the pancreas. Recently it was shown that atropine administration to pigeons was associated with changes in pancreatic enzyme secretion and synthesis (1). The present investigations were performed for two reasons: (a) to obtain additional specific information concerning the mechanism of action of atropine on pancreatic protein synthesis; and (b) to determine general mechanisms concerned with reduction of pancreatic protein synthesis.

These studies show that uridine-³H incorporation into tissue RNA was decreased 2, 4, and 6 hr following atropine administration. However, no change was apparent in uridine-³H incorporation into nuclear RNA 2 and 4 hr following atropine. The major decrease in uridine-³H incorporation was into soluble RNA. Pancreatic microsomes and supernatant from atropine-treated birds incorporated fewer counts following in vitro incubation than microsomes and supernatant from saline-treated birds. These results suggest that the initial decrease in l-phenylalanine-¹⁴C incorporation results primarily from changes involving the translational level of protein synthesis.

Methods. Fasted or fed white Carneau pigeons, age 6-8 weeks (wt 500 g) were used for all studies (2). All animals had free access to water.

Materials and methods used have been previously described (2-4).

Pigeons (control group, 3 birds; atropine group, 3 birds) were given atropine, 0.8 mg/kg, or saline in pectoral muscles according to the following schedules: (1- and 2-hr studies) atropine, 0.4 mg each 30 min, two or four times; (4- and 6-hr studies) atropine, 0.4 mg each hour, four or six times; saline, 1.0 ml was given to control birds at the same time. Atropine administration at these doses and periods of time resulted in no apparent change in the well being of the animals.