Development of a Sensitive Somatostatin Radioimmunoassay and its Application to Plasma of Stressed and Non-Stressed Rats

Abstract

A sensitive somatostatin radioimmunoassay was developed and immunoreactive somatostatin was measured in plasma of different vessels of stressed and non-stressed rats. Detection limit of the assay is 4 pg/ml. Serial dilutions of rat plasma run parallel to the standard curve. On gel chromatography of rat plasma immunoreactive somatostatin elutes at the position of synthetic somatostatin. Immunoreactive somatostatin in plasma of non-stressed rats is (mean ± 1 SEM) 368 ± 58, 244 ± 66, 273 ± 61, 260 ± 44, 359 ± 80 pg/ml in aorta abdominalis, vena cava, vena renalis, vena jugularis, vena porta respectively. After stress mean immunoreactive somatostatin was higher in plasma of all vessels, in aorta abdominalis (p ≤ 0.01), vena renalis and vena porta about 50 per cent, in vena jugularis and vena cava about 90 per cent (p ≤ 0.002). We conclude that under conditions like stress somatostatin circulates in increased amounts and perhaps reaches organs distant from documented sources.