[A pharmacokinetic study of 125I-VIP in rat]

To investigate the pharmacokinetics of 125I-VIP in normal rats, a single dose of 125I-VIP was given intravenoualy to rats and from 0.5 to 240 min after the administration, serial blood samples were taken and measuredp by gamma scintillation counter and finally expressed as mu Ci/ml blood. The data were analyzed by computer for the estimation of pharmacokinetic parameters and the judgment of compartment model with a program of 3P87. The results demonstrated that the pharmacokinetics of 125I-VIP in rat fitted with the three-compartment model(Wi = 1) based on either the comparison of the calculated theoretic value with measured concentration, the values of AIC and r2 or F test for the model judgment, and that the average distributive half-life of 125I-VIPk in blood was 1.36 min, the elimination half-life(T1/2 beta was 67.3 min, the K12(3.589 min-1) was markedly higher than that of K12(0.045 min-1), and the K21:K12(0.0127) was obviously lower than that of K31:K13(0.215). The present study indicates that 125I-VIP has a rapid uptake and slow elimination in the tissues with high density and affinity VIP receptors (the second compartment).