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A L Widdison

Publications and source records attributed to A L Widdison.

38 records · Page 3Linked to original sources

The effect of dopamine in a model of biliary acute hemorrhagic pancreatitis.

Perfusion of the main pancreatic duct in cats with a dilute solution of bile salts increases ductal permeability. Subsequent perfusion of a permeable duct with activated pancreatic enzymes results in acute edematous pancreatitis. Simultaneous infusion of 16-16 dimethyl-PgE2 converts edematous pancreatitis to acute hemorrhagic pancreatitis (AHP). AHP may be associated with a reduction in pancreatic blood flow; it is certainly associated with increases in microvascular permeability. Low dose dopamine is a splanchnic vasodilator and may also reduce pancreatic microvascular permeability through beta agonist effects. In these studies, we investigated the effect of dopamine in an established feline model of biliary AHP. We also studied its effect on blood flow in both normal pancreas and after induction of AHP. We found that dopamine significantly reduced the degree of pancreatic inflammation, even when administered up to 12 h after onset of biliary AHP. However, the drug had no significant effect on blood flow either in normal pancreas or in the gland affected by hemorrhagic pancreatitis. We concluded that the effect of dopamine was most likely due to its ability to reduce pancreatic microvascular permeability.

16,16-Dimethylprostaglandin E2↗

Ketamine and the guinea-pig ileum: possible opiate agonist and antagonist actions and effects of peptidase inhibition.

The effects of ketamine and its interaction with naloxone were studied on the transmurally stimulated guinea-pig ileum preparation. Ketamine (at concentrations between 10(-4) and 10(-3) M) depressed the contractions of the ileum, showing a very steep log concentration-effect curve. Naloxone partially reversed the depressant effect of ketamine at slightly higher concentrations (between 10 nM and 1 microM) than those normally required to reverse opiate depression in this tissue. Naloxone did not affect pentobarbitone-induced depression, suggesting that ketamine has specific actions on opiate transmission. Phentolamine and propranolol did not affect the ketamine-induced depression, whereas acetylcholinesterase inhibition did not alter the action of naloxone on this depression. Ketamine showed some reversal effect on the depressant action of morphine and caused contractions of the morphine-tolerant ileum, suggesting that it may have opiate antagonist activity. Inhibition of peptidase enzymes by a mixture of dipeptides potentiated the depression after high-frequency stimulation of the ileum, but did not affect the action of ketamine. The results suggest that ketamine may interact with opiate mechanisms in the ileum to produce part of its depressant action and may also have some opiate antagonist activity.

Acetylcholine↗