Effect of age on vasoactive intestinal polypeptide-induced short-circuit current in porcine jejunum

Abstract 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 EC 50 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 μA · cm −2 ) than neonatal (57.1±3.6 μA · cm −2 ) and young pigs (63.1±2.9 μA · 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.