PLASMA INSULIN ACTIVITY FOLLOWING THE ADMINISTRATION OF BZ 55 (N-SULFANYLYL-N'-n-BUTYLCARBAMIDE) IN DOGS

(I) Determination of insulin was examined by the rat-diaphragm method, and the following results were obtained: A linear regression was observed between extraglucose uptake and log-concentration of insulin in the range of 10 to 0.01mU/kg. The minimum detectable concentration was 0.003mU/ml, slope of regression line (regression coefficient) b=0.6610, standard deviation of regression line S=0.1674, index of precision λ=0.253 (intervals between consecutive doses, 10-fold).(II) Plasma insulin activity in 14 normal fasting dogs, estimated by this method was 0.347±0.184mU/ml. Change in plasma insulin activity was observed after administration of insulin, glucose and BZ 55 (N-sulfanylyl-N'-n-butyl-carbamide) with the following results:1. After intravenous administration of 1U/kg of insulin, plasma insulin activity increased from 0.229mU/ml before to 4.655m, U/ml at 10mins. became 0.645mU/ml at 30 mins. after.2. After subcutaneous administration of 0.2-0.8U/kg of insulin the results were as follows: In case of 0.2U/kg, plasma insulin activity always remained in the normal range; but in the case of 0.6U/kg, it increased significantly after the injection. The minimum dose of insulin in subcutaneous injection which produced increase in plasma insulin activity was 0.4U/kg.3. After the intravenous injection of 1g/kg of glucose, 0.347mU/ml before the injection became 0.933mU/ml at 30mins., indicating increase.4. After intraperitoneal administration of 50mg/kg of BZ 55, 0.287-0.382mU/ml before the injection became 0.180mU/ml at 1hr. and 2hrs. After the intravenous administration of 100mg/kg, 0.471mU/ml before the injection became 0.336mU/ml at 1hr., 0.283mU/ml at 2hrs. and 0.301mU/ml at 4 hrs. In all the cases, there was no significant difference in plasma insulin activity between before and after the administration.(III) No significant effect of BZ 55 was observed in vitro experiments on the basal uptake and insulin effect by the isolated rats diaphragm.