M.R.C. Blood Pressure Unit, Western Infirmary, Glasgow, G11 6NT
(Received 27 August 1975)
The rat has been widely used in the investigation of the physiology and pathology of the renin—angiotensin system. This paper describes an adaptation of the radioimmunoassay of angiotensin II in human plasma (Dusterdieck & McElwee, 1971) for use in the rat.
Antibodies against [Asn1, Val5]-angiotensin II (Hypertensin, Ciba) were raised in rabbits using a minor modification of the method described by Goodfriend, Fasman, Kemp & Levine
(1966). The antiserum used cross-reacted 100% with [Asp1, He5]-angiotensin II (Schwartz-Mann), 2–8 heptapeptide (Ile4), and 3–8 hexapeptide (Ile3) fragments but only 0·6% with [Asp1,Ile5]-angiotensin I and 0·008% with rat renin substrate obtained from dialysed nephrectomized rat plasma.
Since the octapeptide native to the rat is thought to be in the Ile5 form (Powell-Jackson, Brown, Lever, Macgregor, Macadam, Titterington, Robertson & Waite, 1972), [Asp1, Ile5]-angiotensin II was iodinated with Na125I as described