Dexmedetomidine Exerts Dose-Dependent Age-Independent Antinociception but Age-Dependent Hypnosis in Fischer Rats

Maturational differences in the effects and mechanisms of action of endothelin 1 (ET-1) on airway contractility were investigated in tracheal smooth muscle (TSM) segments isolated from 2-wk-old and adult rabbits. In TSM under passive tension, ET-1 elicited dose-dependent contractions, with a potency of action that was significantly greater (P less than 0.001) in the 2-wk-old vs. adult tissues (i.e., mean +/- SE - log 50% of maximal response values: 8.59 +/- 0.17 vs. 7.79 +/- 0.15 - log M, respectively). In TSM half-maximally contracted with acetylcholine (ACh), however, ET-1 elicited dual and opposing dose-dependent effects. At lower doses (less than or equal to 10(-9) M), ET-1 induced TSM relaxation that was significantly greater in the adult vs. 2-wk-old TSM segments (i.e., approximately 100 vs. 26.5% decrease in active tension, respectively). The relaxant responses were associated with significantly enhanced (P less than 0.001) ET-1-induced release of prostaglandins E2 and I2 in the adult tissues. At higher doses (greater than 10(-9) M), ET-1 induced TSM contractions that were 1) attenuated to a relatively greater extent by the Ca2+ channel blocker, nifedipine (10(-5) M) in the 2-wk-old tissues and 2) associated with significantly (P less than 0.001) enhanced ET-1-stimulated accumulation of inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] in the immature TSM. Moreover, the TSM contractions were inhibited by the protein kinase C (PKC) antagonist, H-7, and the latter effect was more potent in the immature TSM. Collectively, these findings demonstrate that ET-1 exerts a potent duality of action in rabbit TSM which varies significantly with maturation, wherein 1) age-dependent differences in airway relaxation are associated with changes in the evoked release of bronchodilatory prostaglandins and 2) maturational differences in airway contraction are associated with changes in Ins(1,4,5)P3 accumulation and extracellular Ca2+ mobilization, coupled to differences in PKC activation.

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Age-Independent Adult Mortality in a Long-Lived Herb

Diversity ◽

10.3390/d11100187 ◽

2019 ◽

Vol 11 (10) ◽

pp. 187 ◽

Cited By ~ 1

Author(s):

Edelfeldt ◽

Lindell ◽

Dahlgren

Keyword(s):

General Pattern ◽

Cost Of Reproduction ◽

Mortality Rates ◽

Adult Mortality ◽

Trade Offs ◽

Age Dependent ◽

Annual Mortality ◽

Age Independent ◽

Long Term Studies

Relative to mammals and birds, little is known about the mortality trajectories of perennial plants, as there are few long-term demographic studies following multiple yearly cohorts from birth to death. This is particularly important because if reproductively mature individuals show actuarial senescence, current estimations of life spans assuming constant survival would be incorrect. There is also a lack of studies documenting how life history trade-offs and disturbance influence the mortality trajectories of plants. We conducted Bayesian survival trajectory analyses (BaSTA) of a 33-year individual-based dataset of Pulsatilla vulgaris ssp. gotlandica. Mortality trajectories corresponded to “Type III” survivorship patterns, with rapidly decreasing annual mortality rates for young plants, but with constant mortality for reproductively mature individuals. We found trade-off effects resulting in a cost of growth for non-reproductive plants but no apparent cost of reproduction. Contrarily to our expectation, young plants that had previously shrunk in size had a lower mortality. However, accounting for trade-offs and disturbance only had minor effects on the mortality trajectories. We conclude that BaSTA is a useful tool for assessing mortality patterns in plants if only partial age information is available. Furthermore, if constant mortality is a general pattern in polycarpic plants, long-term studies may not be necessary to assess their age-dependent demography.

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Age-Independent and Age-Dependent Neural Substrate for Single-Digit Multiplication and Addition Arithmetic Problems

Developmental Neuropsychology ◽

10.1080/87565641.2010.549873 ◽

2011 ◽

Vol 36 (3) ◽

pp. 338-352 ◽

Cited By ~ 13

Author(s):

Xinlin Zhou ◽

James R. Booth ◽

Jiayan Lu ◽

Hui Zhao ◽

Brian Butterworth ◽

...

Keyword(s):

Single Digit ◽

Neural Substrate ◽

Age Dependent ◽

Age Independent

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Nitrous oxide exerts age-dependent antinociceptive effects in Fischer rats

Pain ◽

10.1016/s0304-3959(02)00098-2 ◽

2002 ◽

Vol 100 (1) ◽

pp. 7-18 ◽

Cited By ~ 15

Author(s):

Yoko Ohashi ◽

Janet M Stowell ◽

Laura E Nelson ◽

Toshikazu Hashimoto ◽

Mervyn Maze ◽

...

Keyword(s):

Nitrous Oxide ◽

Antinociceptive Effects ◽

Age Dependent ◽

Fischer Rats

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Age-dependent and age-independent effects of testosterone in male quail

General and Comparative Endocrinology ◽

10.1016/j.ygcen.2014.08.007 ◽

2014 ◽

Vol 208 ◽

pp. 64-72

Author(s):

Charlotte A. Cornil ◽

Melanie Schmit ◽

Catherine de Bournonville ◽

Meg-Anne Ceuleers ◽

Corentin Daulne ◽

...

Keyword(s):

Age Dependent ◽

Independent Effects ◽

Age Independent

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Compartment models for estimating attributes of digesta flow in cattle

British Journal Of Nutrition ◽

10.1079/bjn19880129 ◽

1988 ◽

Vol 60 (3) ◽

pp. 571-595 ◽

Cited By ~ 118

Author(s):

K. R. Pond ◽

W. C. Ellis ◽

J. H. Matis ◽

H. M. Ferreiro ◽

J. D. Sutton

Keyword(s):

Residence Time ◽

Mean Residence Time ◽

Residence Times ◽

Age Dependency ◽

Faecal Excretion ◽

Compartment Models ◽

Equal Rate ◽

Age Dependent ◽

The Mean ◽

Age Independent

1. The basic assumptions involved in one- and two-compartment models with age-independent distributed residence times (exponential, G1) for describing digesta flow are reviewed as the bases for describing families of one- and two-compartment models which assume age-dependent distributions (Gn) of residence times.2. The two-compartment, age-independent model with exponentially distributed residence times (GIGI) yielded estimates of essentially equal rate parameters when fitted to faecal values for all four cows receiving a diet of 500 g coarsely chopped, sodium hydroxide-treated straw /kg and one of four cows receiving the same diet but with ground and pelleted straw. The incorporation of progressively higher orders of age dependency (G2-G6, Gn) into the faster turnover compartment of two-compartment models (GnG1) resulted in a resolution of equal rate parameters estimated by the G1G1 model and a reduction in standard errors for the rate and the initial concentration parameters.3. The occurrence of equal rate parameters in two-compartment models indicated an age-dependent process; a process which could equally well be described by a one-compartment, age-dependent compartment having an order of age dependency equal to the sum of these orders in the two-compartment model with equal rate parameters.4. The age-independent models overestimated time of first appearance in the faeces of a meal's particles. The association of age dependency with the faster turnover compartment resulted in earlier estimates for first appearance of the marked particles; estimates which were more consistent with observed first appearance.5. The faecal excretion pattern from cows fed on the ground and pelleted straw diet exhibited an age-independent distribution of longer residence times which dominated approximately 80% of the later residence times. Age-dependent, one-compartment models gave a poor fit to such data from these cows fed on ground and pelleted straw. In contrast, age-dependent, one-compartment models provided an excellent fit to data from cows fed on chopped straw; data which indicated that age-independent distributions of residence times were much delayed in appearing or were totally absent.6. The mean residence time for the slower turnover, age-independent compartment estimated from faecal excretional of stained particles from either diet was similar to that estimated from duodenal concentrations of the stained particles. This suggests that the slower turnover model compartment was confined to preduodenal sites.7. The mean residence time for the faster turnover, age-dependent compartment estimated from duodenal data was 58–62 % that estimated from faecal data and suggests that the site of this model compartment was both pre- and post-duodenal.8. It is emphasized that the slow and imperfect mixing of particulate matter that occurs in reticulo-rumen digesta is inconsistent with the assumptions of instantaneous and homogeneous mixing made by models having age-independent distributions of residence times. The use of age-dependent distributed residence times can accommodate such imperfect mixing and is consistent with the existence of age-discriminating processes involved in particle flow from the reticulo-rumen. Age dependency also offers improved precision in estimating parameters of digesta flow via processes having inherent uncertainty in their mixing and age-discriminating mechanisms.

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