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Digitale Medien

Early and late effects of low-dose famotidine, ranitidine or placebo on pentagastrin-stimulated gastric acid secretion in man (1996)

GRIMLEY, C. E. ; WEST, J. M. ; LOFT, D. E. ; [weitere]

Oxford BSL : Blackwell Science

Alimentary pharmacology & therapeutics 10 (1996), S. 0

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Details

ISSN: 1365-2036

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Medizin

Notizen: Background: There are no published comparative studies on the effect of low-dose H2-antagonists on pentagastrin-stimulated gastric acid secretion. Methods: Twenty-four healthy subjects were dosed with either famotidine 10 mg, ranitidine 75 mg or placebo in a balanced three-period cross-over design. The subjects were studied in groups of 12, simultaneously, under identical controlled environmental conditions. Gastric juice was aspirated in 15-min aliquots during sub-maximal (0.6 μg . h/kg) intravenous pentagastrin stimulation in the third and fourth hours (early period) and the eighth and ninth hours (late period) after oral dosing. The hydrogen ion (H+) content of gastric juice was measured ex vivo, by titrating to pH 7 known volumes of gastric aspirate against 0.1 m sodium hydroxide, using a versatile microprocessor-controlled auto-titration unit. Gastric acid output during the period of interest was calculated by adding the hydrogen ion content of 15-min aliquots collected during that period. The geometric mean of the cumulative pentagastrin-stimulated gastric acid output during the early and late periods was determined for the subjects dosed with either famotidine, ranitidine or placebo. Comparisons were performed by ANOVA. Results: During the early period (2–4 h post-dose), when the subjects were given placebo, mean gastric acid output was 46.6 mmol, decreasing by 76% to 11.3 mmol (P〈0.001) when treated with famotidine and by 76% to 11.1 mmol (P〈0.001) when treated with ranitidine. During the late period (7–9 h post-dose), when the subjects were dosed with placebo, mean gastric acid output was 41.2 mmol, decreasing by 38% to 25.7 mmol (P〈0.001) when treated with famotidine and by 27% to 30.0 mmol (P=0.007) when treated with ranitidine. The difference between the inhibitory effects of famotidine and ranitidine on gastric acid output were non-significant during either period. Conclusions: Low-dose famotidine and ranitidine, intended for over-the-counter use, inhibit stimulated gastric acid secretion profoundly in the third and fourth hours after an oral dose. Modest effects are still detectable up to 9 h after dosing.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1046/j.1365-2036.1996.51193000.x

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Digitale Medien

Developmental changes in the activation properties and ultrastructure of fast- and slow-twitch muscles from fetal sheep (1999)

West, J. M. ; Barclay, C. J. ; Luff, A. R. ; [weitere]

Springer

Journal of muscle research and cell motility 20 (1999), S. 249-264

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ISSN: 1573-2657

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Medizin

Notizen: Abstract At early stages of muscle development, skeletal muscles contract and relax slowly, regardless of whether they are destined to become fast- or slow-twitch. In this study, we have characterised the activation profiles of developing fast- and slow-twitch muscles from a precocial species, the sheep, to determine if the activation profiles of the muscles are characteristically slow when both the fast- and slow-twitch muscles have slow isometric contraction profiles. Single skinned muscle fibres from the fast-twitch flexor digitorum longus (FDL) and slow-twitch soleus muscles from fetal (gestational ages 70, 90, 120 and 140 days; term 147 days) and neonatal (8 weeks old) sheep were used to determine the isometric force pCa (pCa = −log10[Ca2+]) and forcepSr relations during development. Fast-twitch mammalian muscles generally have a greatly different sensitivity to Ca2+ and Sr2+ whereas slow-twitch muscles have a similar sensitivity to these divalent cations. At all ages studied, the forcepCa and force pSr relations of the FDL muscle were widely separated. The mean separation of the mid-point of the curves (pCa50−pSr50) was ∼1.1. This is typical of adult fast-twitch muscle. The force-pCa and force-pSr curves for soleus muscle were also widely separated at 70 and 90 days gestation (pCa50−pSr50∼0.75); between 90 days and 140 days this separation decreased significantly to ∼0.2. This leads to a paradoxical situation whereby at early stages of muscle development the fast muscles have contraction dynamics of slow muscles but the slow muscles have activation profiles more characteristic of fast muscles. The time course for development of the FDL and soleus is different, based on sarcomere structure with the soleus muscle developing clearly defined sarcomere structure earlier in gestation than the FDL. At 70 days gestation the FDL muscle had no clearly defined sarcomeres. Force (N cm-2) increased almost linearly between 70 and 140 days gestation in both muscle types and there was no difference between the Ca2+- and Sr2+-activated force throughout development.