Vitamin E alters hepatic antioxidant enzymes in rats treated with dehydroepiandrosterone (DHEA).

The effects of vitamin E on hepatic antioxidant enzymes and plasma indicators of tissue damage were studied in rats treated with dehydroepiandrosterone (DHEA). Thirty-two male Sprague-Dawley rats were randomly allotted to one of four groups of eight rats each. Rats were treated with DHEA [100 mg/(kg body wt.d), i.p.], vitamin E (1 g/kg diet), or DHEA+vitamin E, or were untreated (controls) for 5 wk. Treatment with DHEA reduced (P < 0.05) weight gain, fat pad weight and carcass lipid concentration and increased carcass protein and ash concentration compared with control rats. The DHEA-treated rats had significantly lower concentrations of serum triglycerides and total cholesterol, yet greater amounts of liver lipid, than did control rats. Supplementation of DHEA-treated rats with vitamin E had no significant effect on weight gain, carcass composition or plasma metabolites compared with rats treated with DHEA alone. The rate of hepatic peroxisomal fatty acid oxidation in DHEA-treated rats was approximately 240% of that in control or vitamin E-supplemented rats. The specific activities of enzymes that defend against oxidative stress (e.g., glutathione reductase, glutathione transferase, catalase) or are indicators of tissue damage (e.g., alanine and aspartate aminotransferases) were all significantly higher in DHEA-treated rats compared with control rats. Supplementation of DHEA-treated rats with vitamin E generally reduced these indices of oxidative stress compared with rats treated with DHEA alone, suggesting that vitamin E may have a protective effect against potential oxidative damage associated with DHEA treatment.

Computer-assisted video measurement of inhibition of ciliary beat frequency of human nasal epithelium in vitro by xylometazoline.

The effect of xylometazoline, an alpha-adrenergic agonist, on ciliary beat frequency (CBF) was tested on samples of human nasal epithelium in vitro. Ciliated tissue was obtained from the inferior nasal turbinates of five normal individuals. CBF was measured from video recordings of ciliary activity using a computer-assisted photometric technique. The mean CBF of cells from the five subjects, followed for 40 min without xylometazoline, was 12.0 +/- 1.1 Hz. All concentrations of xylometazoline significantly decreased ciliary beat frequency. After a 10-min exposure, the mean CBF dropped to 3.8 +/- 0.4 with 0.1% xylometazoline, 4.9 +/- 1.0 with 0.05%, and 8.1 +/- 0.9 with 0.025%. Washing with control culture medium at least partially reversed the inhibition within 10 min. Phentolamine (10(-3) M), an alpha-adrenergic antagonist, did not alter CBF significantly when used alone, but partially blocked the strong cilioinhibitory effect of xylometazoline. This action of xylometazoline is similar to that of several commercially prepared decongestants that contain potentially ciliotoxic preservatives in addition to alpha-adrenergic agonists and supports the view that alpha-adrenergic agonists act directly on ciliated cells to inhibit ciliary activity.

Features of developing ferret tracheal epithelium: ultrastructural observations of in vivo and in vitro differentiation of ciliated cells.

Ultrastructural features of the developing, surface epithelium of ferrets from birth to 28 days of age were characterized. Progressive ciliogenesis in vivo was observed, beginning with cells covering the membranous portion of the trachea. Emerging cilia appeared in ultrathin sections and by scanning electron microscopy at sites correlating with accumulation of integral membrane particles seen in freeze-fracture preparations. Two patterns of ciliogenesis were observed: (1) the random emergence of cilia over the apical cell surface, and (2) initial emergence of cilia at the peripheral boundary of the luminal border of individual cells. Novel, ringlike structures were observed on the surfaces of nonciliated cells at all ages studied. Active ciliogenesis as well as the appearance of ring structures also were documented in the superficial epithelium from 1- to 5-day-old animals maintained in vitro for up to 4 days.

Regulation of mucociliary transport. Response of mucous cells to stimulation by amiloride applied to the frog palate in vitro.

Mucociliary transport (MCT) over the surface of isolated frog palatal epithelium was significantly inhibited by the diuretic drug amiloride (50% at 10(-5)M); this occurred when the drug was applied to the mucosal but not to the submucosal surface. The rate of ciliary beating was unchanged by treatment with amiloride (13.5 +/- 1.3 Hz, amiloride; 13.4 +/- 1.4 Hz, control). Spontaneous reversal of inhibition of MCT occurred after extended rinsing (1.5 to 3 h) with Ringer's solution; however, addition of mucus immediately restored MCT to control level. Amiloride applied to the mucosal surface stimulated 2.5 to 3 times as many cells to discharge mucus; this was correlated with an increase of 28% in apparent viscoelasticity of the mucus transport layer measured in situ (approximated by determining breaking strength of mucus using a surface tension balance). Other effects of mucosal application of amiloride included reduction of the transepithelial electrical potential by 62% and increased sodium (17%) in secreted mucus. This is the first report of a stimulatory effect by amiloride on mucous secretory cells.