Effect of age on vasoactive intestinal polypeptide-induced short-circuit current in porcine jejunum.
Vasoactive intestinal polypeptide is a transmitter at the neuroepithelial junction of the small intestine in cholera toxin-induced secretion. We investigated whether the secretory effect in vitro of vasoactive intestinal polypeptide in porcine jejunum was changed with age. Stripped tissue preparations from three age groups, neonatal (7-11 days), young (6-8 weeks) and adult (13-15 weeks) pigs, were mounted in Ussing chambers and short-circuited. Vasoactive intestinal polypeptide produced concentration dependent increases in short-circuit current in all three age groups with EC50 values (in nM) of 14.5 +/- 1.9, 16.2 +/- 2.0 and 147 +/- 0 in neonatal, young and adult pigs, respectively. The peak increases in short-circuit current in adult pigs were significantly decreased compared with the other two age groups. To evaluate the secretory capacity, theophylline was added to tissue preparations in which baseline short-circuit current again was established. Theophylline caused a significantly lesser increase in short-circuit current in adult pigs (25.4 +/- 2.0 microA.cm-2) than neonatal (57.1 +/- 3.6 microA.cm-2) and young pigs (63.1 +/- 2.9 microA.cm-2). In conclusion, vasoactive intestinal polypeptide showed a marked decrease in the secretory response with age in porcine jejunum, at least partly caused by a reduced secretory capacity of the enterocytes.
Erlwanger
K H
KH
Faculty of Veterinary Science, University of Zimbabwe, Harare.
Unmack
M A
MA
Grøndahl
M L
ML
Skadhauge
E
E
Thorbøll
J E
JE
D000375:Aging / Q000502:physiology*; D000818:Animals; D007583:Jejunum / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D013552:Swine; D013806:Theophylline / Q000494:pharmacology; D014660:Vasoactive Intestinal Peptide / Q000502:physiology*
D014660:Vasoactive Intestinal Peptide; D013806:Theophylline