Comparison of the half-lives and regeneration rates of blood clotting factors II, VII, and X in anticoagulant-resistant and susceptible Norway rats (Rattus norvegicus Berk.).

The half-lives and regeneration rates of clotting factors II, VII, and X in the plasma of anticoagulant-resistant and susceptible rats were determined. There is little or no difference in the half-lives of factors II and X in anticoagulant-resistant rats compared to susceptible rats, but the half-life of factor VII is longer in anticoagulant-resistant rats. In anticoagulant-resistant rats critical clotting factors appear to be carboxylated in preference to factor II, whereas the opposite occurs in susceptible rats; this may contribute to an animal's resistance status.

Symptom-dependent taste aversion induced by an anticoagulant rodenticide in the brown rat (Rattus norvegicus).

In a series of 3 experiments with different experimental paradigms, feeding patterns of laboratory rats (Rattus norvegicus) were monitored in 2-choice feeding tests after intubation with a sublethal dose of an anticoagulant rodenticide. We report for the first time that contrary to accepted wisdom, anticoagulants can induce taste aversions. Furthermore, we report behavioral symptoms within the 1st day after dosing. Our data suggest that the taste aversion is induced through an inhibition of the vitamin K cycle and is transient, attenuating over the same period as the levels of vitamin K-dependent proteins return to normal. Because the taste aversion is expressed most strongly when symptoms are most pronounced and is not expressed after symptoms have disappeared, we term this novel form of control symptom-dependent taste aversion.

The development of a blood clotting response test for discriminating between difenacoum-resistant and susceptible Norway rats (Rattus norvegicus, Berk.).

1. A new test for identifying levels of difenacoum resistance in the Norway rat is described, based upon the differential physiological response to difenacoum administration. 2. This test is based on changes in blood clotting activity over 4 days, following administration of the rodenticide difenacoum in conjunction with menadione (vitamin K3). 3. The anticoagulant effect is reduced only in rats that are resistant or tolerant to difenacoum. 4. This test procedure is quicker than traditional feeding tests, and identifies the degree of resistance in both laboratory and wild rats that have difenacoum resistance genes.