Dopamine in models of alcoholic acute pancreatitis.

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Abstract
Acute oedematous pancreatitis and acute haemorrhagic pancreatitis were studied using the low pressure duct perfusion models of alcoholic pancreatitis in cats. After creating either form over 24 hours, each pancreas was histologically graded and assigned an inflammatory score (0-16; absent-severe). Urinary trypsinogen activation peptide concentrations were also used as a measure of severity. Using the model of acute haemorrhagic pancreatitis, it was previously shown that low dose dopamine (5 micrograms/kg.m) reduced the inflammatory score at 24 hours and that this effect was mediated by a reduction in pancreatic microvascular permeability acting via dopaminergic and beta adrenergic receptors. Further studies were conducted and are reported here. In experiment 1 different doses of dopamine in established alcoholic acute haemorrhagic pancreatitis were studied. In group 1 control cats (no dopamine), the inflammatory score was 10.5 (interquartile range (IQR)4). In groups 2, 3, and 4, haemorrhagic pancreatitis was induced. Twelve hours later dopamine was infused for six hours, in the doses of 2 micrograms/kg.min, 5 micrograms/kg.min, and 50 micrograms/kg.min respectively. The inflammatory score in group 2 was 7 (IQR 0.5, p < 0.05 v group 1), in group 3 it was 7 (IQR 2, p < 0.05 v group 1), and in group 4 it was 7 (IQR 4, p < 0.05 v group 1). This was matched by significantly lower levels of urinary tripsinogen activation peptide at 24 hours. In experiment 2 (group 5) we tried to reduce microvascular permeability further by combining dopamine with antihistamines, but there was no improvement in the inflammatory score. As oedematous pancreatitis is the commoner and milder form of acute pancreatitis in clinical practice, in experiment 3 we looked at the effect of dopamine in this model. In group 6 control cats (no treatment), the inflammatory score was 7 (IQR 3, p < 0.05 v group 1). In group 7 cats given dopamine (5 micrograms/kg.min for six hours) from 12 hours after the onset of actue oedematous pancreatitis, the inflammatory score was reduced to 4(IQR 2, p < 0.05 v group 6). This was matched by a significant reduction in the 24 hour urinary tripsin activation peptide concentration.