Assessment of Glucagon Immunoreactivity in Plasma

Weir, Gordon C.

doi:10.1007/978-1-4612-6366-1_5

Cited by 4 publications

(2 citation statements)

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“…Pms-F had much less effect, and pepstatin had no effect on either IRG or glucagon degradation. (1974 and 1975) and others (Weir, 1977;Jaspan et al, 1981). Fig.…”

Section: Resultsmentioning

confidence: 89%

“…forms of immunoreactive glucagon (IRG) have been found in plasma (Valverde et al, 1974 and1975;Jaspan et al, 1976 andValverde, 1977;Weir, 1977;Jaspan, 1982). Filtration of whole plasma from humans and other animals on Bio Gel P-10 or P-30 yields at least two major fractions of IRG: one with a molecular weight of about 3,500 (IRG3500) and another with a large molecular weight which appears in the void volume.…”

Section: Differentmentioning

confidence: 99%

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Glucagon degradation in fraction of big plasma glucagon in rats treated with carbon tetrachloride.

et al. 1983

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When whole plasma obtained from rats given carbon tetrachloride was applied to a column of Bio Gel P-30, P-150 or P-300, a large molecular form of immunoreactive glucagon (IRG), so called "big plasma glucagon " (BPG), was eluted in the void volume. Glucagon degrading activity, measured under the same conditions as for radioimmunoassay of IRG, was eluted in parallel with IRG. Since standard assay mixture containing aprotinin was used for the measurement of IRG, this degradation of glucagon might be due to an enzyme(s) other than serine proteinases.p-Hydroxymercuribenzoate depressed glucagon degradation and IRG in the BPG fractions to 20% and 30% of the control values, respectively. Other inhibitors of thiol proteinases, such as N-ethylmaleimide and leupeptin, also decreased the values for both glucagon degradation and IRG to a similar extent. However, phenylmethylsulfonyl fluoride and pepstatin had little or no effect on these values. On filtration of plasma from carbon tetrachloride-treated rats on a column of Bio Gel A-1.5 m, IRG peaks between 600 k and 1,200 k daltons were obtained and glucagon degrading activity was again eluted with IRG. When p-chloromercuriphenyl sulfonate and N-ethylmaleimide were added to the elution buffer and assay mixtures, the glucagon degrading activity was almost completely inhibited and the values for IRG between 600 k and 1,200 k daltons were decreased to less than 10% of those of the control. These results indicate that more than 90% of the IRG in the fractions of BPG obtained from carbon tetrachloride-treated rats could be accounted for entirely by the degradation of immunoreactive 125I-glucagon by plasma proteinases, probably thiol proteinases.Thus we conclude that some proteinases are still active in the radioimmunoassay system of glucagon which is widely used at present, and lead apparently higher glucagon values owing to degradation of 125I-glucagon.

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“…Pms-F had much less effect, and pepstatin had no effect on either IRG or glucagon degradation. (1974 and 1975) and others (Weir, 1977;Jaspan et al, 1981). Fig.…”

Section: Resultsmentioning

confidence: 89%