Partial characterization of angiotensin II-like material extracted from the rat brain

Angiotensin II (ANG II)-like material was detected in acid extracts of rat brain using radio-immunoassay (RIA) and a radioreceptor assay (RRA). This material, expressed as ANG II equivalents, corresponded to 131 +/- 20 fmol/g and 33 +/- 4 pmol/g as assessed by RIA and RRA respectively. Such quantitative differences indicated that the brain material did not behave as authentic ANG II in both assays, and further chromatographic investigations confirmed this inference. In particular, gel filtration through Sephadex G-25 and TSK Spherogel 3000 SW revealed that the apparent molecular weight of ANG II-like material was much higher (approximately 5000-7000) than that of authentic ANG II. Furthermore, in contrast to the marked hypertension due to ANG II, a decrease in blood pressure (BP) was observed in rats following the systemic administration of chromatographic eluates enriched with brain ANG II-like material.