The effect of TGFα on intestinal solute transport

The effect of transforming growth α (TGFα) and epidermal growth factor (EGF) on 3-O- methylglucose transport was examined in vitro under short-circuited conditions in stripped rabbit jejunum. Mucosal EGF, 60 ng/ml, stimulated a significant increase in net 3-O- methylglucose transport ( J net 0.67 ± 0.15 vs. 0.90 ± 0.15 μ Eq/cm 2/ h ; P < 0.03; n = 6) due to an increased mucosal to serosal flux ( J ms 1.2 ± 0.2 vs. 1.5 ± 0.2 μ Eq/cm 2/ h ; P < 0.03). In contrast, TGFα, when applied to both mucosal and serosal surfaces at concentrations of either 60 ( n = 6) or 150 ( n = 9) ng/ml had no effect on either mucosal to serosal ( J ms ) or net transport ( J net ) of 3-O- methylglucose . TGFα did induce a significant increase in the serosal to mucosal flux ( J sm 60 ng/ml 0.44 ± 0.02 vs. 0.51 ± 0.03, 150 ng/ml 0.55 ± 0.03 vs. 0.64 ± 0.05 μ Eq/cm 2/ h ; P < 0.05). When brush border surface area was examined after exposure to either 60 ng/ml TGFα or saline vehicle for 2 h in in vivo isolated jejunal loops no significant difference was found (control 53 ± 1.9; n = 35 vs. TGFα 52 ± 1.9 μ m 2 ; n = 29). Bioactivity of transforming growth factor α was assessed by an gastric acid secretion bioassay and found to be intact. These data provide further evidence for separate and distinct functional roles for these peptides in some biological systems.