Immunoreactive secretin concentrations were measured in femoral venous plama and in
interstinal perfusates during acid and neutral perfusion of small intestinal segments
in anesthetized rabbits. Steady-state plasma and luminal secretin concentrations were
<20 pg/ml. Duodenal perfusion with with 0.1 N hydrochloric acid stimulated peak plasma
immunoreactive secretin concentrations of 200-300 pg/ml within five minutes. Acid
stimulated plasma concentrations remained constant during 30 minutes of perfusion.
Secretin output into the acid perfusate (2000-4000 pg/min) accompanied the release
into plasma. Subsequent perfusion with a neutral solution resulted in a rapid return
to steady-state plasma and luminal secretin concentrations. Sequential acid perfusion
of the ileum, jejunum, and duodenum stimulated similar concentrations of secretin
in plasma and luminal perfusates.
Secretin
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Radioimmunoassay
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Luminal Hormone
