scholarly journals Role of chloride-mediated inhibition in respiratory rhythmogenesis in an in vitro brainstem of tadpole, Rana catesbeiana.

1996 ◽  
Vol 492 (2) ◽  
pp. 545-558 ◽  
Author(s):  
R J Galante ◽  
L Kubin ◽  
A P Fishman ◽  
A I Pack
Keyword(s):  
Rana Catesbeiana ◽  
Respiratory Rhythmogenesis

H(+)-K(+)-ATPase contributes to regulation of pHi in frog oxynticopeptic cells

1991 ◽  
Vol 261 (5) ◽  
pp. G781-G789 ◽  
Author(s):  
A. Yanaka ◽  
K. J. Carter ◽  
P. J. Goddard ◽  
M. C. Heissenberg ◽  
W. Silen
Keyword(s):  
Steady State ◽  
Gastric Mucosa ◽  
Histamine Release ◽  
Rana Catesbeiana ◽  
Intracellular Acidosis ◽  
Endogenous Histamine ◽  
Decreasing Ph ◽  
Oxynticopeptic Cells

The effect of intracellular acidosis on luminal H+ secretion and the role of H(+)-K(+)-ATPase in regulation of intracellular pH (pHi) in oxynticopeptic cells (OPC) (measured with a pH-sensitive fluorescent dye) were examined in intact sheets of in vitro frog (Rana catesbeiana) gastric mucosa. Intracellular acidosis of OPC induced by decreasing pH in the serosal solution (pHs) from 7.2 to 6.0 reversibly increased forskolin-stimulated H+ secretion without increasing endogenous histamine release. The observed increase in H+ secretion was unaffected by either 1 mM cimetidine or 1 mM histamine, but was accentuated by 1 mM amiloride, an effect abolished by 0.3 mM omeprazole. Steady-state pHi values in stimulated or resting OPC at pHs 7.2 were not significantly different. However, pHi in OPC was significantly higher in stimulated than in resting tissues at pHs 6.9, a difference accentuated by decreasing pHs to 6.4 or by 1 mM amiloride. Amiloride completely prevented recovery from intracellular acidosis induced by pHs 6.4 or 6.9 in omeprazole-treated tissues, but only partially mitigated recovery in cimetidine- or forskolin-treated tissues. At pHs 6.4, high luminal [K+] (100 mM) increased H+ secretion and hastened recovery of pHi in cimetidine-treated tissues in the presence of amiloride. These results suggest that, in intact sheets of in vitro frog gastric mucosa, 1) intracellular acidosis stimulates luminal H+ secretion via histamine-independent mechanisms and 2) H(+)-K(+)-ATPase contributes to the recovery of OPC from intracellular acidosis.

Sites of respiratory rhythmogenesis during development in the tadpole

2001 ◽  
Vol 280 (4) ◽  
pp. R913-R920 ◽  
Author(s):  
C. S. Torgerson ◽  
M. J. Gdovin ◽  
J. E. Remmers
Keyword(s):  
Brain Stem ◽  
Rana Catesbeiana ◽  
Lung Ventilation ◽  
Respiratory Rhythmogenesis ◽  
Amphibian Larvae ◽  
Before And After ◽  
Lung Ventilator ◽  
Necessary And Sufficient ◽  
Stem Segments

During ontogeny, amphibian larvae experience a dramatic alteration in the motor act of breathing as the premetamorphic gill breather develops into the postmetamorphic lung ventilator. We tested the hypothesis that the site of lung rhythmogenesis relocates during metamorphosis by recording fictive lung ventilation before and after transecting the in vitro brain stem of pre- and postmetamorphic Rana catesbeiana into four segments. In premetamorphic tadpoles, the two caudalmost brain stem segments combined proved to be the minimum brain stem configuration necessary and sufficient for lung burst generation. In the postmetamorphic counterpart, this function was supplied by the combination of the two rostralmost brain stem segments. In the postmetamorphic brain stem, a 500-μm segment lying just rostral to cranial nerve IX conveys rhythmogenic capability to neighboring rostral or caudal segments. We conclude that lung rhythmogenic capability translocates rostrally during development as the tadpole shifts from gill to lung ventilation.

Central respiratory activity of the tadpole in vitro brain stem is modulated diversely by nitric oxide

2002 ◽  
Vol 283 (2) ◽  
pp. R417-R428 ◽  
Author(s):  
Michael B. Harris ◽  
Richard J. A. Wilson ◽  
Konstantinon Vasilakos ◽  
Barbara E. Taylor ◽  
John E. Remmers
Keyword(s):  
Nitric Oxide ◽  
Rana Catesbeiana ◽  
Lung Ventilation ◽  
Central Chemosensitivity ◽  
Respiratory Rhythmogenesis ◽  
Specific Frequency ◽  
Central Respiratory Activity ◽  
Ph Conditions ◽  
Respiratory Rhythms

Nitric oxide (NO) is a potent central neuromodulator of respiration, yet its scope and site of action are unclear. We used 7-nitroindazole (7-NI), a selective inhibitor of endogenous neuronal NO synthesis, to investigate the neurogenesis of respiration in larval bullfrog ( Rana catesbeiana) isolated brain stems. 7-NI treatment (0.0625–0.75 mM) increased the specific frequency of buccal ventilation (BV) events, indicating influence on BV central rhythm generators (CRGs). The drug reduced occurrence, altered burst shape, and disrupted clustering of lung ventilation (LV) events, without altering their specific frequency. LV burst occurrence and clustering also differed between pH conditions. We conclude that NO has diverse effects on respiratory rhythmogenesis, being necessary for the expression of respiratory rhythms, inhibiting the frequency of BV CRG, and affecting both shape and clustering of LV bursts through conditional modulation of LV CRG. We confirm central chemosensitivity in these preparations and demonstrate chemomodulation of LV burst clustering and occurrence but not specific frequency. Results support distinct oscillators underlying LV and BV CRGs.

The role of silicon in forages: A quantitative X-Ray study

1987 ◽  
Vol 45 ◽  
pp. 416-417
Author(s):  
Janet H. Woodward ◽  
D. E. Akin
Keyword(s):  
Sodium Acetate ◽  
Dry Matter ◽  
Acetate Buffer ◽  
Plant Tissues ◽  
Sodium Acetate Buffer ◽  
X Ray ◽  
Dry Matter Digestibility ◽  
Percent Composition

Silicon (Si) is distributed throughout plant tissues, but its role in forages has not been clarified. Although Si has been suggested as an antiquality factor which limits the digestibility of structural carbohydrates, other research indicates that its presence in plants does not affect digestibility. We employed x-ray microanalysis to evaluate Si as an antiquality factor at specific sites of two cultivars of bermuda grass (Cynodon dactvlon (L.) Pers.). “Coastal” and “Tifton-78” were chosen for this study because previous work in our lab has shown that, although these two grasses are similar ultrastructurally, they differ in in vitro dry matter digestibility and in percent composition of Si.Two millimeter leaf sections of Tifton-7 8 (Tift-7 8) and Coastal (CBG) were incubated for 72 hr in 2.5% (w/v) cellulase in 0.05 M sodium acetate buffer, pH 5.0. For controls, sections were incubated in the sodium acetate buffer or were not treated.

An integrated screening method for evaluating the pulmonary toxicity of inhaled particulates: Role of microscopic techniques in assessing pulmonary macrophage clearance functions

1990 ◽  
Vol 48 (3) ◽  
pp. 826-827
Author(s):  
David B. Warheit ◽  
Lena Achinko ◽  
Mark A. Hartsky
Keyword(s):  
Bronchoalveolar Lavage ◽  
Pulmonary Toxicity ◽  
Screening Method ◽  
Pulmonary Response ◽  
Inhaled Particles ◽  
Cytochemical Analysis ◽  
Pulmonary Macrophages ◽  
Integrated Screening

There is a great need for the development of a rapid and reliable bioassay to evaluate the pulmonary toxicity of inhaled particles. A number of methods have been proposed, including lung clearance studies, bronchoalveolar lavage analysis, and in vitro cytotoxicity tests. These methods are often limited in scope inasmuch as they measure only one dimension of the pulmonary response to inhaled, instilled or incubated dusts. Accordingly, a comprehensive approach to lung toxicity studies has been developed.To validate the method, rats were exposed for 6 hours or 3 days to various concentrations of either aerosolized alpha quartz silica (Si) or carbonyl iron (CI) particles. Cells and fluids from groups of sham and dust-exposed animals were recovered by bronchoalveolar lavage (BAL). Alkaline phosphatase, LDH and protein values were measured in BAL fluids at several time points postexposure. Cells were counted and evaluated for viability, as well as differential and cytochemical analysis. In addition, pulmonary macrophages (PM) were cultured and studied for morphology, chemotaxis, and phagocytosis by scanning electron microscopy.

The Role of Polyphenols in the Modulation of Plasma Non-Enzymatic Antioxidant Capacity (NEAC)

2012 ◽  
Vol 82 (3) ◽  
pp. 228-232 ◽  
Author(s):  
Mauro Serafini ◽  
Giuseppa Morabito
Keyword(s):  
Antioxidant Capacity ◽  
Dietary Intervention ◽  
Ex Vivo ◽  
The Body ◽  
Dietary Polyphenols ◽  
Enzymatic Antioxidant ◽  
Endogenous Antioxidant

Dietary polyphenols have been shown to scavenge free radicals, modulating cellular redox transcription factors in different in vitro and ex vivo models. Dietary intervention studies have shown that consumption of plant foods modulates plasma Non-Enzymatic Antioxidant Capacity (NEAC), a biomarker of the endogenous antioxidant network, in human subjects. However, the identification of the molecules responsible for this effect are yet to be obtained and evidences of an antioxidant in vivo action of polyphenols are conflicting. There is a clear discrepancy between polyphenols (PP) concentration in body fluids and the extent of increase of plasma NEAC. The low degree of absorption and the extensive metabolism of PP within the body have raised questions about their contribution to the endogenous antioxidant network. This work will discuss the role of polyphenols from galenic preparation, food extracts, and selected dietary sources as modulators of plasma NEAC in humans.

Anti-obesity role of Aster glehni extract: in vivo and in vitro effects

Planta Medica ◽  
2012 ◽  
Vol 78 (11) ◽  
Author(s):  
HM Lee ◽  
TG Ahn ◽  
CW Kim ◽  
HJ An
Keyword(s):  
In Vitro Effects

Role of the 807 C/T Polymorphism of the α2 Gene in Platelet GP Ia Collagen Receptor Expression and Function

1999 ◽  
Vol 81 (06) ◽  
pp. 951-956 ◽  
Author(s):  
J. Corral ◽  
R. González-Conejero ◽  
J. Rivera ◽  
F. Ortuño ◽  
P. Aparicio ◽  
...  
Keyword(s):  
Venous Thrombosis ◽  
Cell Types ◽  
Receptor Expression ◽  
Case Control Studies ◽  
Platelet Surface ◽  
Vitro Analysis ◽  
And Function ◽  
In Vitro Analysis

SummaryThe variability of the platelet GP Ia/IIa density has been associated with the 807 C/T polymorphism (Phe 224) of the GP Ia gene in American Caucasian population. We have investigated the genotype and allelic frequencies of this polymorphism in Spanish Caucasians. The T allele was found in 35% of the 284 blood donors analyzed. We confirmed in 159 healthy subjects a significant association between the 807 C/T polymorphism and the platelet GP Ia density. The T allele correlated with high number of GP Ia molecules on platelet surface. In addition, we observed a similar association of this polymorphism with the expression of this protein in other blood cell types. The platelet responsiveness to collagen was determined by “in vitro” analysis of the platelet activation and aggregation response. We found no significant differences in these functional platelet parameters according to the 807 C/T genotype. Finally, results from 3 case/control studies involving 302 consecutive patients (101 with coronary heart disease, 104 with cerebrovascular disease and 97 with deep venous thrombosis) determined that the 807 C/T polymorphism of the GP Ia gene does not represent a risk factor for arterial or venous thrombosis.

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