ALKALINE EXTRACTION AND CHARACTERIZATION OF CHOLECYSTOKININ-IMMUNOREACTIVITY FROM RAT GUT

  • 1 January 1981
    • journal article
    • research article
    • Vol. 81  (2) , 267-275
Abstract
Generally some variation of neutral or acid extractants was used to recover immunoreactive cholecystokinin (CCK) from gut and from brain. Recovery of CCK in 0.1 N NaOH extracts from gut mucosa, gut muscle or whole gut ranged up to 3-fold higher than in similar H2O or 0.1 N HCl extracts, although the reverse was the case for the extraction of secretin from the same tissue. CCK-immunoreactive peptides from rat gut resemble a CCK-33-like peptide, sulfated CCK-12 and CCK-8 and smaller COOH-terminal fragments, which are larger than the C-terminal tetrapeptide amide. The fraction of immunoreactivity in the form of a CCK-33-like peptide was greater, although the total recovery was less, in acid extractants of whole gut. Proper interpretation of dynamic changes in gut CCK in response to fasting, feeding and other laboratory manipulations requires efficient extraction of total immunoreactivity.