Perfusion of the jejunum with a mixture of amino acids (MAA) stimulates cholecystokin-in-pancreozymin (CCK) release in man. Since gastrin is normally found in the small intestine, studies were conducted to determine if MAA perfusion had an effect on circulating serum gastrin levels in man. In man, endogenous stimulation of CCK had no effect on gastrin release; however, when CCK was given exogenously (10% pure form), serum, gastrin levels were significantly increased. In dogs, the 10% pure CCK given exogenously also significantly increased gastrin concentrations, while the pure CCK octapeptide did not. Cross-reactivity between CCK and the gastrin antibody was minimal and could not be shown to be responsible for the serum gastrin elevations. Neither the physiological release of CCK in humans nor exogenous administration of CCK octapeptide in dogs at a dose equivalent to maximal stimulation of pancratic secretion in humans significantly altered peripheral venous serum levels of immunoreactive gastrin. Therefore, we conclude that the gastrinemic response of exogenous CCK (10% pure) in man and dog is problably due to an impurity in the CCK preparation; when studying the effects of CCK on the gastrointestinal tract, only the pure CCK or the octapeptide should be used.
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