Postconditioning (PostC) is a re cently discovered phenomenon whereby brief repetitive cycles of ischaemia with intermittent reperfusion following prolonged is chaemia elicit cardioprotection. This study investigated whether the age, genetic characteristics or number of repetitive cycles influenced the protective effect of PostC in mice. C57BL/6 floxed or non-floxed STAT-3 mice aged between 14-16 weeks (young) or 18-20 weeks (older) were perfused on a Langendorff apparatus and subjected to 35 min global ischaemia and 45 min reperfusion. PostC was elicited by either 3 (PostC-3) or 6 cycles (PostC-6) of 10s ischaemia and 10 s reperfusion. PostC-3 and PostC-6 in both young and older non-floxed mice reduced the myocar dial infarct size. In contrast, only PostC-3 reduced myocardial infarct size in young floxed mice. Neither PostC-3 nor PostC-6 reduced the in farct in older floxed mice. Our data reveal that genetic characteristics, a minute difference in age or the nu mber of postconditioning cycles are critical factors to be consid ered for the successful effect of ischaemic postconditioning in a murine model. Moreover, these factors should be taken into consideration for future experimental research or clinical applications of this protective phenomenon., S. J. Somers ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Several aspects of growth and feeding of C. paludica have been assessed in two different environments: a lenitic and a lotic hydrosystem, Portil lagoon and Rivera de Cala river respectively. Growth patterns showed some differences with Iberian loach growing slower in the lagoon than in the river. Because of this, although individuals of both populations reach sexual maturity in their second year (year-class 1+), specimens of lagoon population mature at smaller sizes. The C. paludica population in the river showed a better somatic condition than in the lagoon. In both hydrosystems, their diet was mainly chironomid larvae and ostracods, although the Portil lagoon Iberian loach population showed a clear trophic segregation between young of the year (year-class 0+) and sexually matures individuals (year-class ≥ 1+).
Metaschistura cristata is a small nemacheilid loach species found at a few localities only in Turkmenistan and Iran. The present study reports, for the first time, data on its biology, based on 747 specimens collected from the River Zanglanlou in north-eastern Iran. Specimens were collected at monthly intervals over two reproductive seasons from February to June 2007 and 2008. Maximum age, based on opercula readings, was 4+ years for both sexes. Specimens ranged in size from 25 to 87 mm total length and weighed from 0.09 to 4.91 g. Length-weight relationships implied positive allometric growth for both sexes and the sex ratio was 1 : 1.2 in favour of females. The Gonadosomatic indicated that peak reproduction occurred during April and May, with highest average values of 1.473 ± 0.99 for males and 12.9 ± 7.14 for females in April. Oocyte diameter ranged from 0.53 to 1.46 mm, with a mean value of 0.943 mm. Absolute and relative fecundity ranged between 114-1246 eggs and 79.47-1285.71 eggs/g, respectively. Absolute fecundity and oocyte diameter to fish size (length and weight) were directly correlated, while the relationship between relative fecundity and fish size (length and weight) showed an inverse power function.
GABA exhibits depolarizing action in the immature neurons due to high intracellular activity of chloride ions. It is maintained by cation-chloride cotransporter NKCC1 which is present in immature brain. Bumetanide is a specific inhibitor of this cotransporter. We studied possible anticonvulsant activity of bumetanide in pentyl enetetrazol-induced seizures in three age groups of rat pups (7, 12, and 18 days old). Pretreatment with bumetanide (0.2-1 mg/kg i.p.) resulted in dose-dependent decrease of incidence of the tonic phase of generalized tonic-clonic seizures in 12-day-old rats only. No effect was observed in younger and older animals. Higher dose of bumetanide (2.5 mg/kg) did not affect tonic convulsions but, on the contrary, decreased latencies of generalized seizures in 12-day-old animals. Lack of marked anticonvulsant effect is probably due to relative maturity of neurons in the brainstem where the generator of generalized seizures is localized. Age- and dose-specific suppression of the tonic phase needs further analysis. and Obsahuje seznam literatury
Altered Ca2+ handling may be responsible for the development of cardiac contractile dysfunctions with advanced age. In the present study, we investigated the roles of oxidative damage to sarcoplasmic reticulum (SR) and expression of Ca2+-ATPase (SERCA 2a) and phospholamban in age-associated dysfunction of cardiac SR. SR vesicles were prepared from hearts of 2-, 6-, 15-, and 26-month-old Wistar rats. Although activity of Ca2+-ATPase decreased with advancing age, no differences in relative amounts of SERCA 2a and phospholamban protein were observed. On the other hand, significant accumulation of protein oxidative damage occurred with aging. The results of this study suggest that agerelated alteration in Ca2+-ATPase activity in the rat heart is not a consequence of decreased protein levels of SERCA 2a and phospholamban, but could arise from oxidative modifications of SR proteins. Cellular oxidative damage caused by reactive oxygen species could contribute to age-related alternations in myocardial relaxation., E. Babušíková ... [et al.]., and Obsahuje seznam literatury
Age-associated changes in large blood vessels were characterized by increased arterial wall thickness, luminal dilation and impaired endothelial function. But little is known about the effect of age on structural and functional changes in small resistance arteries. The mechanisms underlying age-associated endothelial dysfunction in rat mesenteric resistance arteries were investigated in the present study. Small rat mesenteric arteries were excised and cannulated, and vascular endothelial functions were tested by acetylcholine (ACh). Our experiments showed (1) endotheliumdependent vasorelaxation induced by ACh was reduced in aged mesenteric arteries; (2) blockade of Kca channels markedly reduced the vasodilation in young and adult rats, the resultant reduction in aged rats was much smaller compared with young and adult rats; (3) inhibition of endothelial nitric oxide synthase (NOS) resulted in a significant reduction of vasodilation in young and adult, but there was a smaller reduction in aged rats. The results suggest that (1) endothelial function was impaired in mesenteric arteries of aged rats; (2) both Kca channels and nitric oxide (NO) contribute together to the ACh-induced vasorelaxation in small mesenteric arteries, and (3) both the impairment of Kca channel function and decreased NO account for the age-related endothelial dysfunction., E. Zhou, D. Qing, J. Li., and Obsahuje bibliografii a bibliografické odkazy
The age-dependent changes in baroreflex control of heart rate were studied in inbred Dahl rats. At the age of 8 weeks the baroreflex slope was significantly greater in salt-resistant (R/Jr) than in salt-sensitive (S/Jr) rats fed a low- salt diet. The reverse was true in 16-week-old animals. High salt intake (8 % NaCI diet for 4 weeks) suppressed baroreflex efficiency in both age groups of S/Jr animals whereas no effects occurred in R/Jr rats. Baroreflex slope was, however, significantly lower in young S/Jr rats with a severe form of salt hypertension than in adult salt-loaded S/Jr rats in which only a moderate blood pressure elevation was observed.
The oxidative stress hypothesis of aging suggests that accumulation of oxidative damage is a key factor of the alterations in physiological function during aging. We studied age-related sensitivity to oxidative modifications of proteins and lipids of cardiac sarcoplasmic reticulum (SR) isolated from 6-, 15- and 26-month-old rats. Oxidative stress was generated in vitro by exposing SR vesicles to 0.1 mmol/l FeSO4/EDTA + 1 mmol/l H2O2 at 37 °C for 60 min. In all groups, oxidative stress was associated with decreased membrane surface hydrophobicity, as detected by 1-anilino-8-naphthalenesulfonate as a probe. Structural changes in SR membranes were accompanied by degradation of tryptophan and significant accumulation of protein dityrosines, protein conjugates with lipid peroxidation products, conjugated dienes and thiobarbituric acid reactive substances. The sensitivity to oxidative damage was most pronounced in SR of 26-month-old rat. Our results indicate that aging and oxidative stress are associated with accumulation of oxidatively damaged proteins and lipids and these changes could contribute to cardiovascular injury., E. Babušíková, M. Jeseňák, D. Dobrota, N. Tribulová, P. Kaplán., and Obsahuje bibliografii a bibliografické odkazy
The growth of the prostate gland is androgen-dependent. Testosterone is converted to the most potent dihydrotestosterone (DHT) by 5α-reductase within the prostate. Androgen interacts with androgen receptors (AR) to regulate normal growth of the prostate and has also been implicated in both the progression of benign prostate hyperplasia and prostate cancer. This study was conducted to compare the mRNA expression of AR and 5α-reductase by the prostate gland from three age categories: immature, young-mature and old dogs. Quantitative gene expression was assessed by the real-time PCR and the results were expressed as a relative mRNA expression of the target gene. This study revealed that there was no significant difference in the mRNA expression of the AR gene by the prostate gland of immature, young and old dogs. In contrast, there is a highly significant (P<0.001) down-regulation in 5α-reductase gene by the prostate of young and old dogs as compared with immature dogs. However, there is no significant difference in mRNA expression of the 5α-reductase gene by the prostate gland from young and old dogs. This differential expression of AR and 5α-reductase genes, which are involved in the regulation of androgen effect on prostate gland, might reflect an age-dependent growth requirement of the gland for androgens., F. Shidaifat., and Obsahuje seznam literatury
The effects of phenytoin on threshold intensities of stimulation were studied in cortical epileptic afterdischarges (ADs) in 12-day-old and adult rats with implanted electrodes. Stimulation of the sensorimotor cortical area induced movements directly related to the stimulation as well as EEG afterdischarges (ADs) of the spike-and-wave type and of the limbic type. Rat pups exhibited lower thresholds for stimulation-bound movements and spike-and- wave ADs than adult animals. On the contrary, the limbic type of ADs was elicited with lower current intensity in adult than in immature rats. Phenytoin increased the threshold for stimulation-related movements only in adult rats, whereas threshold intensities for spike-and-wave ADs were increased and thresholds for limbic type of ADs remained uninfluenced in both age groups. The age-dependent effect on stimulation-related movements might be due to a maturation of connectivity in the motor system or to developmental changes in the voltage-gated sodium channels as the main target of phenytoin action.