Specific antibody to hog renal renin and its application to the direct radioimmunoassay of renin in various organs.

We produced anti-hog renin antibodies using as antigens pure hog renal renin that either had been insolubilized or conjugated to tetanus toxoid. High titer antibodies were obtained, which demonstrated different cross-reactivity with renins from other species. A direct radioimmunoassay for renin was developed using antibody, monoiodinated 125I-hog renin, and various methods for separating free and antibody-bound trace. This assay was capable of detecting 40 pg of hog renin and was applied to the determination of renin in hog blood and other organs. Based on the direct measurement of renin by this radioimmunoassay, the renin-like activity (i.e., the ability to generate angiotensin I from renin substrate preparations) of the pituitary gland was found to be due mostly to true renin, whereas the renin activity of other hog tissues, including the adrenal gland, liver, lung, spleen, and submaxillary gland, was not identified as renin and may have been due to cathepsins.