| 1. |
- Azerkan, Leila, et al.
(författare)
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Characterization of oxyntic glands isolated from the rat gastric mucosa
- 2001
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Ingår i: Comparative Biochemistry and Physiology A. - 1095-6433 .- 1531-4332. ; 128:2, s. 349-357
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Tidskriftsartikel (refereegranskat)abstract
- A simple and reproducible method for isolating oxyntic glands from the rat gastric mucosa was developed. The mucosa was incubated with pronase and EGTA, and then treated mechanically to release glands that were separated from single cells by sedimentation. Parietal cells were identified by immunostaining using a monoclonal antibody against H,K-ATPase. The glandular cells appeared morphologically intact. By careful control of the conditions of gland isolation, long glandular structures comprising hundreds of cells surrounding the lumen were obtained. Intraperitoneal injection of Br-deoxyuridine in the rat 1.5 h before the isolation procedure resulted in glands with a labeling of cells in their neck region. The glands were viable, as demonstrated by their ability to respond to various hormones. Histamine dose-dependently stimulated the acid formation which was measured as the accumulation of [14C]aminopyrine. At 100 microM histamine the accumulation was increased 5-10-fold. At 100 nM, pentagastrin potentiated the histamine stimulated accumulation by approximately 40% but pentagastrin alone did not stimulate. The oxyntic glands obtained by the present procedure appear useful for studies on cell physiology, including regulation of acid secretion, cellular interactions, and possibly also differentiation and proliferation mechanisms since long glandular fragments that contained the proliferative zone could be isolated.
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| 2. |
- Bengtsson, Per, et al.
(författare)
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Effects of cholecystokinin on acid formation in glands and cells isolated from rabbit and rat gastric mucosa
- 2000
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Ingår i: Comparative Biochemistry and Physiology A. - 1095-6433 .- 1531-4332. ; 126:1, s. 77-84
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Tidskriftsartikel (refereegranskat)abstract
- Isolated gastric glands and isolated cells prepared from rabbit and rat were studied to analyse the influence of cholecystokinin octapeptide (CCK 8) on histamine stimulated parietal cell acid formation as assessed by [14C]aminopyrine sequestered in acid tissue compartments. In rabbit gastric glands, CCK 8 evoked 32±6% (P<0.01) inhibition of histamine stimulated acid formation, whereas in glands prepared from rat no inhibition was recorded. Instead, CCK 8 seemed to induce a variable increase of the histamine stimulation in rat gastric glands as the aminopyrine accumulation was increased by 110±46% (P<0.1). Further studies on cell preparations derived from rabbit gastric mucosa revealed dual properties of CCK 8, eliciting either inhibition or stimulation of the parietal cell depending on the presence of endocrine cells. The results show that paracrine communication may be effective in glandular preparations, but seems to vary depending on species.
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| 5. |
- Antonopoulou, Efthimia, et al.
(författare)
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Effects of aromatase inhibitors and different doses of testosterone on gonadotropins in one year old male Atlantic salmon (Salmo salar).
- 2009
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Ingår i: Comparative biochemistry and physiology. Part A, Molecular & integrative physiology. - : Elsevier BV. - 1531-4332 .- 1095-6433. ; 153:4, s. 408-16
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Tidskriftsartikel (refereegranskat)abstract
- The effects of different doses of testosterone (T), the aromatase inhibitors 1,4,6-androstatriene-3,17-dione (ATD) and 4-hydroxy-4-androstene-3,17-dione (4OH), and the combined treatment of T and ATD on luteinizing hormone (LH) and follicle-stimulating hormone (FSH) at the onset of puberty in juvenile Atlantic salmon males were investigated. T always increased pituitary LH. Also, ATD increased pituitary LH, though to a lesser extent than T. However, ATD combined with T diminished pituitary LH levels compared to T alone, indicating an aromatase-dependent positive feedback of T on LH in immature males. 4OH, which was less effective than ATD as an aromatase inhibitor, increased LH content. ATD treatment resulted in increased pituitary FSH levels, similar to those of mature controls. Positive effects of ATD on plasma FSH were found, indicating the presence of an aromatase-dependent negative feedback. The 4OH effects on FSH levels were inconsistent. T exerted both positive and negative effects on pituitary FSH and testes growth, depending on dose and season, with the positive effects being more pronounced with the low doses and the negative effects with the high doses. The treatment of T combined with ATD did not affect the positive effect of T alone on pituitary and plasma FSH, indicating the presence of an aromatase-independent positive feedback on FSH. There was a positive correlation between FSH and gonadosomatic index, especially during summer when gonadal development occurs.
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| 7. |
- Bagatto, B., et al.
(författare)
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Physiological variability in yearling alligators: Clutch differences at rest andduring activity
- 2012
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Ingår i: Comparative Biochemistry and Physiology - Part A. - : Elsevier. - 0300-9629 .- 1095-6433. ; Part A:162, s. 44-50
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Tidskriftsartikel (refereegranskat)abstract
- The adult phenotype of an organism is the result of its genotype, the environment, and the interaction betweenthe two. Assessing the relative contribution of these factors to the final adult phenotype continues tooccupy researchers. Studies have shown clutch effects early in development but few have investigated thepersistence of clutch effects on a longer time scale. Five clutches of American alligators were reared for1 year in a common environment then assessed for the presence of clutch effects as they related to morphologicaland physiological characteristics. After 1 year, significant clutch effects were evident in all size relatedvariables despite open access to food. Additionally, lung and liver masses remained different betweenclutches after animal mass was taken into account. Although clutch had no effect on resting heart rate, itsignificantly contributed to mean arterial pressure. During swimming and exhaustive exercise, the resultingrespiratory and metabolic acidoses were strongly dependent on clutch. Therefore, while the environmentcan have significant influences on the American alligator from hatching to death, the measureable contributionof genetics to the morphology and physiology of the organism remains evident, even after 1 year ofcommon rearing conditions. It behooves researchers to acknowledge and control for clutch effects when designingexperiments.
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| 8. |
- Basse, W. C., et al.
(författare)
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A sea urchin Na+K+2Cl- cotransporter is involved in the maintenance of calcification-relevant cytoplasmic cords in Strongylocentrotus droebachiensis larvae
- 2015
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Ingår i: Comparative Biochemistry and Physiology A. - : Elsevier BV. - 1095-6433. ; 187, s. 184-192
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Tidskriftsartikel (refereegranskat)abstract
- The cellular mechanisms of calcification in sea urchin larvae are still not well understood. Primary mesenchyme cells within the larval body cavity form a syncytium to secrete CaCO3 spicules from intracellular amorphous CaCO3 (ACC) stores. We studied the role of Na+K+2Cl- cotransporter (NKCC) in intracellular ACC accumulation and larval spicule formation of Strongylocentrotus droebachiensis. First, we incubated growing larvae with three different loop diuretics (azosemide, bumetanide, and furosemide) and established concentration-response curves. All loop diuretics were able to inhibit calcification already at concentrations that specifically inhibit NKCC. Calcification was most effectively inhibited by azosemide (IC50=6.5μM), while larval mortality and swimming ability were not negatively impacted by the treatment. The inhibition by bumetanide (IC50=26.4μM) and furosemide (IC50=315.4μM) resembled the pharmacological fingerprint of the mammalian NKCC1 isoform. We further examined the effect of azosemide on the maintenance of cytoplasmic cords and on the occurrence of calcification vesicles using fluorescent dyes (calcein, FM1-43). Fifty micromolars of azosemide inhibited the maintenance of cytoplasmic cords and resulted in increased calcein fluorescence within calcification vesicles. The expression of NKCC in S. droebachiensis was verified by PCR and Western blot with a specific NKCC antibody. In summary, the pharmacological profile of loop diuretics and their specific effects on calcification in sea urchin larvae suggest that they act by inhibition of NKCC via repression of cytoplasmic cord formation and maintenance.
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