排序方式: 共有62条查询结果,搜索用时 46 毫秒
11.
In vitro cardiac performance in triploid brown trout at two acclimation temperatures 总被引:1,自引:0,他引:1
C. Mercier M. Axelsson N. Imbert G. Claireaux C. Lefrançois J. Altimiras A. P. Farrell 《Journal of fish biology》2002,60(1):117-133
The maximum values for heart rate ( f H ), stroke volume ( V H ), cardiac output ( Q ) and myocardial power output, measured in vitro with a perfused heart preparation, as well as the isometric force-frequency relationship for atrial and ventricular muscle strips, in triploid brown trout Salmo trutta were all comparable with established information for diploid rainbow trout Oncorhynchus mykiss . Therefore, it was concluded that triploidy is not associated with a major deficiency in maximum cardiac performance. However, a heightened sensitivity to ryanodine was discovered, which indicated an enhanced role for the sarcoplasmic reticulum in excitation-contraction coupling in these triploid fish. It is suspected that the enhanced role of the ryanodine receptor may be a cellular compensation related to larger cardiac myocytes. It was also clearly established that there was a plateau in maximum cardiac performance between 14 and 18° C and this plateau might be a contributing factor to the reduced factorial aerobic scope and increased fish mortality observed at 18° C. 相似文献
12.
The α1‐adrenergic receptor is involved in hepcidin upregulation induced by adrenaline and norepinephrine via the STAT3 pathway 下载免费PDF全文
13.
14.
Quantification of ventricular β2‐adrenoceptor density and ligand binding affinity in wild sockeye salmon Oncorhynchus nerka smolts using a novel modification to the tritiated ligand technique 下载免费PDF全文
A new, image‐based, tritiated ligand technique for measuring cardiac β2‐adrenoceptor (β2‐AR) binding characteristics was developed and validated with adult rainbow trout Oncorhynchus mykiss hearts so that the tissue limitation of traditional receptor binding techniques could be overcome and measurements could be made in hearts nearly 14‐times smaller than previously used. The myocardial cell‐surface (functional) β2‐AR density of O. nerka smolts sampled at the headwaters of the Chilko River was 54·2 fmol mg protein?1 and about half of that previously found in return migrating adults of the same population, but still more than twice that of adult hatchery O. mykiss (21·1 fmol mg protein?1). This technique now opens the possibility of investigating cardiac receptor density in a much wider range of fish species and life stages. 相似文献
15.
M.F Heath R.W Farndale C.S Napthine L.J Hayes R.J Evans 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》1997,118(4):889-893
Adrenaline is a weak aggregating agonist for human platelets acting through G-protein-coupled α2-adrenoceptors to inhibit adenylate cyclase and thus reduce cyclic AMP levels. Studies of equine platelets have shown that adrenaline is unable to promote their aggregation. We now confirm that adrenaline is without effect on equine platelet aggregation and demonstrate that it is also without effect on equine platelet membrane adenylate cyclase activity. We have previously shown that equine platelet membranes contain conventionally regulated adenylate cyclase activity, with both stimulatory ligands (forskolin and PGE1) and inhibitory ligands (collagen and PAF) each showing substantial and dose-dependent effects. We now show, in Western blots, that equine platelet membranes contain G proteins, including Gi2 (which mediates inhibition of adenylate cyclase by adrenaline in human platelets), Gi3, Gs, and Gq. Hence, all the necessary components and responses are in place in equine platelets to provide for a conventional role for cyclic AMP and adenylate cyclase in modulating platelet aggregation. The basis for the failure of adrenaline, unlike other ligands, to deliver such a signal, appears to be a marked lack of α2-adrenoceptors. This is supported by the low receptor density we found in idazoxan binding studies. 相似文献
16.
Cardiovascular and cerebrovascular disorders are well known to be associated with stress related behaviors. Stress enhances excretion of adrenaline, which is deaminated by monoamine oxidase and methylamine is formed. This product can be further deaminated by semicarbazide-sensitive amine oxidase (SSAO) and converted to toxic formaldehyde, hydrogen peroxide and ammonia. SSAO is located in the cardiovascular smooth muscles and circulated in the blood. We investigated whether formaldehyde can be derived from adrenaline in vivo. Methylamine was confirmed to be a product of adrenaline catalyzed by type A monoamine oxidase (MAO-A). Irreversible and long-lasting radioactive residual activity was detected in different tissues following administration of 1-[N-methyl-3H]-adrenaline. Such irreversible linkage could be blocked by selective MAO-A or SSAO inhibitors. Endothelial cells are quite sensitive to formaldehyde and relatively resistant to hydrogen peroxide. It is possible that stimulation of adrenaline excretion by chronic stress could increase the levels of circulatory formaldehyde. Such chronic formaldehyde stress may be involved in the initiation of endothelial injury and subsequently angiopathy. 相似文献
17.
延髓头端腹外侧区注入肾上腺素对血液流变学的影响 总被引:6,自引:0,他引:6
实验用SD雄性大鼠78只,采用束缚方法引起应激性高血粘度和血压升高。结果:(1)清醒大鼠束缚2d可引起应激性高血粘度和血压升高。(2)双侧延髓头端腹外侧区(rVLM)微量注射肾上腺素(E,每侧0.5μg/0.5μl)可引起血粘度明显增高,此作用可预先在双侧rVLM注入α肾上腺素能受体阻断剂酚妥拉明所阻断,不能被β-肾上腺能受体阻断剂心得安所阻断。用同样剂量E注入双侧延髓尾端腹外侧区(cVLM)或静 相似文献
18.
Incubation with noradrenaline (norepinephrine) of isolated membranes of rat's brain corpus striatum and cortex, showed that ionic-magnesium (Mg2+) is required for the neurotransmitter activatory response of adenylate cyclase [ATP pyrophosphate-lyase (cyclizing) (EC 4.6.1.1)], AC. 相似文献
19.
Perfused rainbow trout Oncorhynchus mykiss hearts exposed to simulated exercise conditions (hypoxia, hyperkalemia and acidosis) at 18° C experienced complete failure of maximum cardiac performance at oxygen tensions <5·6 kPa and partial failure at <6·7 kPa. This hypoxic threshold, which occurred in the presence of maximal adrenergic stimulation (500 nM adrenaline), is unusually high compared with previous results at a colder acclimation temperature. Cardiac failure was primarily due to significant decreases ( P < 0·05) in heart rate rather than cardiac stroke volume at all hypoxia levels tested. 相似文献
20.
Pous'kov A. N. Sharykina N. I. Pavlovskaya G. P. Kirichok L. M. Karatsuba T. A. 《Neurophysiology》2000,32(6):390-394
We studied the effects of treatments with adrenaline hydrochloride, obsidan (a -adrenoblocker), melipramine (an inhibitor of monoamine uptake by neurons), and reserpine (a sympatholytic drug) on tumor growth (Pliss' lymphosarcoma in rats) and on the antitumor activity of a novel cytostatic drug, chlofiden. We found that adrenaline and reserpine enhanced the antitumor effect of chlofiden. Isolated applications of adrenaline and melipramine exerted slight antitumor effects, while after reserpine treatment there was a trend toward stimulation of tumor growth. Under the conditions of the model used, obsidan demonstrated no noticeable antitumor activity and did not modify the antitumor effect of chlofiden. Possible mechanisms of the observed effects are discussed. 相似文献