Carrageenan and dextran in rats.

Carrageenan injected subcutaneously into one hindpaw of the rat produces an anaphylactoid reaction which prevents the same paw responding to a second dose 14 days later but does not alter the response to dextran. However, dextran does not modify the response of the hindpaw to a subsequent dose of either dextran or carrageenan 14 days later. When using these models of inflammation for testing the anti-inflammatory activity of drugs, valuable extra information may be gained by adopting the cross-over technique and using both paws of each animal.