On the Components of the Kr85Wash‐Out Curves from the Small Intestine of the Cat

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Abstract
The wash‐out of intra‐arterially injected Kr35from denervated small intestinal segments (mainly jejunum) of the cat was recorded by means of a scintillation detector at various levels of vascular tone. The elimination curve could be resolved into four components (I‐IV) at all blood flow levels. Four independent methods were used in an attempt to localize the different componerits, namely, registration of the elimination of β‐activity, local injections into different parts of the intestinal segment, autoradiography and comparisons of weights of the compartments. The following localization of the four components was made probable. The first component reflected predominantly a countercurrent exchange of krypton between the ascending and descending limbs of the vascular loops in the mucosa at “resting” flow levels. During vasodilatation, this component mirrored mainly the wash‐out of the tracer from a well‐perfused region in the mucosa‐submucosa. The second and third components mainly reflected the disappearance of Kr85from the mucosa and the muscularis, respectively. The slowest component (IV) probably mirrored an elimination of Kr85from the perivascular fat of the mesentery and an absorption of the tracer from the intestinal lumen.