Similarity between active and trypsin-activated inactive renin in dog plasma by means of renin inhibition: the dog as an animal model for studies of inactive renin.
A method for trypsin-activation of dog plasma inactive renin is described. Liquid phase trypsin (final concentration 6.7 mg/ml) was used and the reaction was stopped after 2 min at 4 degrees C by soybean trypsin inhibitor (13 mg/ml). Renin was measured as angiotensin I (Ang I) generation in trypsin-treated and untreated plasma using the antibody-trapping method, in the presence of excess ox renin substrate. The renin-like activity after trypsin was indeed due to renin, since Ang I generation in dog plasma before and after trypsin treatment was completely inhibited by H-77 at 10(-6) mol/l, and the two IC50 values were very similar (2.7 +/- 0.7 and 2.9 +/- 0.7 at 10(-8) mol/l, respectively). Dog plasma inactive renin was effectively separated from active renin by chromatography on Affigel Blue. Like human prorenin, dog plasma inactive renin rose in response to sodium depletion (furosemide 5 mg/kg, i.v.) followed by a low-salt diet (1 mmol Na+/day) for 4 days, (from 29.6 +/- 8 to 162 +/- 22 microU/ml; P less than 0.01, n = 10). Active renin also increased as expected. Intravenous captopril (6 mg/kg per h), for 3 h, led to a sharp increase in dog plasma active renin (from 53 +/- 8 to 360 +/- 60 microU/ml; P less than 0.01, n = 6), whereas inactive renin remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)
Tonolo
G
G
MRC Blood Pressure Unit, Western Infirmary, Glasgow, UK.
Tree
M
M
Pazzola
A
A
Leckie
B J
BJ
D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D002846:Chromatography, Affinity; D004285:Dogs; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000378:metabolism*; D005665:Furosemide / Q000494:pharmacology; D008297:Male; D009842:Oligopeptides / Q000494:pharmacology*; D012083:Renin / Q000096:biosynthesis* / Q000378:metabolism*; D012982:Sodium, Dietary / Q000008:administration & dosage; D014357:Trypsin / Q000378:metabolism*; D000092502:Renin Inhibitors
D000806:Angiotensin-Converting Enzyme Inhibitors; D004792:Enzyme Precursors; D005665:Furosemide; D009842:Oligopeptides; D012083:Renin; D012982:Sodium, Dietary; D014357:Trypsin; D000092502:Renin Inhibitors; C034503:H 77