Unexpected effects of pathogens on epithelial Na+ channels.
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Animals↗
Biomedical subjects
A Beesley
Publications and source records attributed to A Beesley.
Influence of peppermint oil on absorptive and secretory processes in rat small intestine.
BACKGROUND: Peppermint oil is used to relieve the symptoms of irritable bowel syndrome, relaxing intestinal smooth muscle by reducing the availability of calcium, but its effects on intestinal transport are unknown. AIMS: To determine the effect of peppermint oil on intestinal transport processes. METHODS: The influence of peppermint oil on intestinal transport was investigated in rat jejunum using both intestinal sheets mounted in Ussing chambers and brush border membrane vesicles. RESULTS: Mucosal peppermint oil (1 and 5 mg/ml) had no significant effect on basal short circuit current, but inhibited the increase associated with sodium dependent glucose absorption. The increased short circuit current induced by serosal acetylcholine, a reflection of calcium mediated electrogenic chloride secretion, was unaffected by mucosal peppermint oil (5 mg/ml). In contrast, serosal peppermint oil (1 mg/ml) inhibited the response to acetylcholine without reducing the effect of mucosal glucose. In brush border membrane vesicles active glucose uptake was inhibited by extravesicular peppermint oil at concentrations of 0.5 and 1 mg/ml. CONCLUSIONS: Peppermint oil in the intestinal lumen inhibits enterocyte glucose uptake via a direct action at the brush border membrane. Inhibition of secretion by serosal peppermint oil is consistent with a reduced availability of calcium.
Absorption↗
5-Hydroxytryptamine induces electrogenic secretion and simultaneously activates a modulating inhibitory neural circuit in rat small intestine in vitro.
5-Hydroxytryptamine (5-HT) induces electrogenic secretion across rat jejunum and ileum in vitro expressed as an increase in the short-circuit current. Enhancement of this secretory response by previous serosal addition of atropine (1 microM), hexamethonium (0.2 microM) or yohimbine (0.2 microM), especially in the ileum, indicated that 5-HT simultaneously activates an anti-secretory, inhibitory, enteric, neural, cholinergic-adrenergic pathway (ENCAP). A similar inhibitory ENCAP activated by 5-HT has previously been characterized in rat colon in vitro.
Animals↗
Histopathology of the skin of UV-B irradiated sole (Solea solea) and turbot (Scophthalmus maximus) larvae.
Larval stages of two economically important flatfish, the sole (Solea solea) and turbot (Scophthalmus maximus) were exposed to ambient and elevated levels of UV-B. Sole larvae, which naturally occur in the plankton in early spring, demonstrated skin lesions at elevated levels of UV-B. Histopathology of the sole revealed cellular changes in the integument, characteristic of sunburn damage, with a reduction in the size of mucus-secreting cells and an increased epidermal thickening, especially at the highest doses of UV-B (2.15 KJ bio eff/m2). Pigmentation in the sole is restricted to a few isolated melanocytes. The integrity of the heavily pigmented skin of turbot appeared to be unaffected by comparable doses of UV-B. Both species have protective mechanisms, which minimize the effects of naturally-occurring levels of UV-B. However, sole appear to be poorly adapted to accommodate any further increase in solar radiation.
Adaptation, Physiological↗