Isolation and purification of a vascular hyperreactivity factor from rabbit kidney cortex.

ABSTRACT

A compound capable of amplifying the threshold pressor response to norepinephrine (NE) was obtained from rabbit kidney cortex. This compound was purified and characterized using a series of techniques including gel filtration, ion exchange chromatography, preparative electrofocusing, HPLC, FAB mass spectrometry (FAB-MS), and Fourier transform infrared spectrometry. From this, an acid/heat stable (6N HC1, 160 degrees C, 24 hours), low molecular weight (ca 147) compound with a strong (+) charge density (Pi greater than 10) was identified. When injected into assay rats (i.v.), this compound amplified the pressor response to fixed doses of NE. Taken together, this compound exhibits nearly identical characteristics (i.e. acid/heat stability, structure, charge and biologic activity to the naturally occurring polyamine spermidine (SPD-145.6 daltons). Moreover, bolus injections of SPD (10 micrograms, i.v.) amplified the pressor response to NE over a range of doses from 5-25 ng.