glands and small intestine. There are wide interspecies differences for the plasma
amylase levels, and tissue distribution of amylase (Rajasingham et al., 1971; McGeachin
and Akin, 1982). The number of isoenzymes in different species varies, and plasma
amylase in the plasma may be the pancreatic (P) isoamylase or (S) isoamylase from the
salivary gland: in mice it is reported that serum amylase is of salivary origin while
urinary amylase is of pancreatic origin (MacKenzie and Mosser, 1976). Total plasma
amylase is more commonly measured as salivary changes are relatively uncommon, but
they do occur in some conditions such as sialoadenosis (Arglebe et al., 1978). The
plasma P amylase is probably a more sensitive and specific assay for pancreatitis in some
species where this assay works. The half-life of amylase is short, varying from less than 2
Assessment of gastrointestinal toxicity and pancreatic toxicity 135
h in the mouse to 5 h in the dog. Urinary amylase is generally increased where plasma
amylase is increased, but it offers no major diagnostic advantage over plasma
measurements because it is also affected by renal injury and disease.