AJP - Gastrointestinal and Liver Physiology, Vol 243, Issue 6 511-G517, Copyright © 1982 by American Physiological Society
Postnatal development of intestinal secretin in rats and guinea pigs
T. L. Paquette, D. F. Shulman, D. H. Alpers and B. M. Jaffe
The amounts and concentrations of secretin in extracts of rat and guinea
pig small intestine were measured with a porcine secretin radioimmunoassay.
Immunoactivity in the extracts comigrated with porcine secretin in sodium
dodecyl sulfate acrylamide gel electrophoresis. In the small intestines of
adult rats and newborn and adult guinea pigs, there was a marked
proximal-to-distal gradient in secretin concentration; newborn rats
exhibited approximately equal proximal and distal secretin concentrations.
Concentrations were as follows: most proximal newborn or adult guinea pig
segments, 80 ng/mg prot; most distal newborn or adult guinea pig segments,
2 ng/mg prot; most proximal adult rat segments, 50 ng/mg prot; most distal
adult rat segments, 8 ng/mg prot; and newborn rat intestine, 11 ng/mg prot.
In either rats or guinea pigs, the secretin concentration in the proximal
small intestine fell between days 2 and 6 postpartum to levels 3- and
10-fold below their respective newborn values. It is consistent with the
relatively mature state of the newborn guinea pig digestive tract that it
displays the proximal-to-distal gradient of secretin that is characteristic
of both adult guinea pigs and rats. In the proximal intestine of both
species, intestinal growth outpaces the accumulation of secretin.
