Acute phase plasma proteins in kininogen-deficient Brown Norway rats

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Abstract
We examined whether Brown Norway rat plasma (BN/May Pfd f) contains .alpha.1-cysteine proteinase inhibitor (.alpha.1-CPI), also called major acute phase .alpha.1-protein or T-kininogen. T-kininogen is a low molecular weight kininogen from which kinin can be released by trypsin but not by kallikreins, The BN plasma reacted with rabbit anti-.alpha.1-CPI gamma globulins. Purified .alpha.1-CPI released a kinin-like activity with trypsin and with homogenate of salivary glands, as Brown Norway rat plasma did. High concentration of added rat urine induced a small release (10%) of kinin from .alpha.1-CPI. Preincubation of Brown Norway rat plasma with rabbit anti-rat .alpha.1-CPI .gamma.-globulins nearly suppressed the kinin-forming substrate of trypsin in this plasma. These results indicated that plasma of our Brown Norway rats contains only .alpha.1-CPI as kinin-forming substrate. This plasma contains low amount of .alpha.2-macroglobulin, while its content in orosomucoid and haptoglobin was a little larger than that of Wistar rat plasma.