[Renal metabolism of endogenous gastrin]

The kidney was thought to be the most important known site of the metabolism of gastrin. Specific mechanisms for gastrin catabolism in vivo have not been elucidated. Very little of the gastrin that is filtered by the kidney homogenates appears in the urine. The kidney tubule contains enzymatic activity that cleaves the C-terminal dipeptide amide from gastrin tetrapeptide, but it is not known if such an enzyme acts on the lager gastrin molecules. Removal of gastrin from the circulation is too rapid to be caused by any specific organ but rather must, be due to some nonspecific widespread metabolic process, probably existing in circulating serum. There are some lingering bits of evidence to suggest that although all capillary beds may extract gastrin equally, the renal bed may be first among equals.