The emetic reflex in a reptile (Crocodylus porosus)

The emetic (vomiting) reflex in a crocodilian, Crocodylus porosus, was char acterised for the first time using the plant alkaloid veratrine (5 mg kg(-1 ) i.v. or i.p.) as an emetic stimulus. The latency to the onset of vomiting was 8.0+/-0.9 min (mean +/- S.E.M., N=5 animals). Vomiting was preceded by a clearly defined set of prodromal behaviours including, in temporal seque nce, rhythmic contraction of the pharynx, sneezing and jaw snapping. Expuls ion of vomitus was not particularly forceful and was accompanied by lateral shaking of the head. Physiological studies revealed that vomiting was acco mpanied by oscillatory (9.1+/-0.7 oscillations over 29.7+/-3.6 s, N=9 episo des in three animals) increases in intraperitoneal pressure (7.0+/-0.9 kPa, cf, 0.7+/-0.1 kPa during respiration). The significance of these results i s discussed in the context of the role(s) of vomiting as a protective refle x and as a mechanism for removal of indigestible food residues (e.g. fur, c laws) from the gut.