Radioimmunoassay of substance P in lung perfusate.
A radioimmunoassay of the undecapeptide substance P (SP) and its application in rabbit lung superfusate has been developed. The assay was based on the use of a radioactive tracer, 125I-SP-Tyr8, which showed, with an excess of antibodies, a specific binding greater than 90% and a nonspecific binding lower than 2%. This tracer was stable for 4 weeks at -20 degrees C. Its specific radioactivity was 384 Ci/mmol. The assay's lower limit of detection was 10 pg/ml (0.7 fmol). The determination of SP in rabbit lung perfusate required extraction and concentration using octadecylsilane cartridges. Under these conditions, the recovery of SP from experiments on lung perfusates (n=4) was 75.0+/-4.5%, and the intraassay and interassay coefficients of variation were 7.3+/-1.9% and 10.7+/-1.3%, respectively. Amounts of SP released in rabbit lung perfusates were determined following stimulation of pulmonary C fibers with capsaicin (10(-4) M). During the stimulation period, the values of SP from lung perfusates (n=6) increased significantly when compared with baseline values.
Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, University of Liège, Belgium.
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Nemmar
P
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Gustin
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Delaunois
J F
JF
Beckers
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J
Sulon
D000818:Animals; D002211:Capsaicin / Q000494:pharmacology; D008168:Lung / Q000187:drug effects / Q000378:metabolism*; D010477:Perfusion / Q000379:methods; D011817:Rabbits; D011863:Radioimmunoassay / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013373:Substance P / Q000493:pharmacokinetics*; D014443:Tyrosine
D013373:Substance P; D014443:Tyrosine; D002211:Capsaicin