The role of the pericardium in cardiac function in the dogfish, Squalus acanthias

Opening the pericardium to the ambient bathing fluid surrounding the in situ perfused dogfish ( Squalus acanthias ) heart caused a precipitous fall in cardiac output. Cardiac output fell by 55% despite the rise of mean input pressure from subambient, to near zero levels. Lower cardiac output caused a fall in mean output pressure but not diastolic pressure as this was set by the experimenters. With the pericardium intact, the heart was filled by suction. With an open pericardium the magnitude of negative input pressures was severely reduced. None the less, far short periods within the cardiac cycle, the heart was still able to generate subambient pressures in the atrium and so draw fluid from the central veins.     

Anti-calcification of bovine pericardium for bioprosthetic heart valves after surface modification with hyaluronic acid derivatives

Surface modification of glutaraldehyde fixed bovine pericardium (GFBP) was successfully carried out with hyaluronic acid (HA) derivatives. At first, HA was chemically modified with adipic dihydrazide (ADH) to introduce hydrazide functional group into the carboxyl group of HA backbone. Then, GFBP was surface modified by grafting HA-ADH to the free aldehyde groups on the tissue and the subsequent HA-ADH hydrogel coating. HA-ADH hydrogels could be prepared through selective crosslinking at low pH between hydrazide groups of HA-ADH and crosslinkers containing succinimmidyl moieties with minimized protein denaturation. When HA-ADH hydrogels were prepared at low pH of 4.8 in the presence of erythropoietin (EPO) as a model protein, EPO release was continued up to 85% of total amount of loaded EPO for 4 days. To the contrary, only 30% of EPO was released from HA-ADH hydrogels prepared at pH=7.4, which might be due to the denaturation of EPO during the crosslinking reaction. Because the carboxyl groups on the glucuronic acid residues are recognition sites for HA degradation by hyaluronidase, the HA-ADH hydrogels degraded more slowly than HA hydrogels prepared by the crosslinking reaction of divinyl sulfone with hydroxyl groups of HA. Following a two-week subcutaneous implantation in osteopontin-null mice, clinically significant levels of calcification were observed for the positive controls without any surface modification. However, the calcification of surface modified GFBP with HA-ADH and HA-ADH hydrogels was drastically reduced by more than 85% of the positive controls. The anti-calcification effect of HA surface modification was also confirmed by microscopic analysis of explan ted tissue after staining with Alizarin Red S for calcium, which followed the trend as observed with calcium quantification.     

Ischemic preconditioning in rat heart: No correlation between glycogen content and return of function

We tested the hypothesis that glycogen levels at the beginning of ischemia affect lactate production during ischemia and postischemic contractile function.Isolated working rat hearts were perfused at physiological workload with bicarbonate buffer containing glucose (10 mmol/L). Hearts were subjected to four different preconditioning protocols, and cardiac function was assessed on reperfusion. Ischemic preconditioning was induced by either one cycle of 5 min ischemia followed by 5, 10, or 20 min of reperfusion (PC5/5, PC5/10, PC5/20), or three cycles of 5 min ischemia followed by 5 min of reperfusion (PC3 × 5/5). All hearts were subjected to 15 min total, global ischemia, followed by 30 min of reperfusion. We measured lactate release, timed the return of aortic flow, compared postischemic to preischemic power, and determined tissue metabolites at selected time points.Compared with preischemic function, cardiac power during reperfusion improved in groups PC5/10 and PC5/20, but was not different from control in groups PC5/5 and PC3 × 5/5. There was no correlation between preischemic glycogen levels and recovery of function during reperfusion. There was also no correlation between glycogen breakdown (or resynthesis) and recovery of function. Lactate accumulation during ischemia was lowest in group PC5/20 and highest in the group with three cycles of preconditioning (PC3 × 5/5). Lactate release during reperfusion was significantly higher in the groups with low recovery of power than in the groups with high recovery of power.In glucose-perfused rat heart recovery of function is independent from both pre- and postischemic myocardial glycogen content over a wide range of glycogen levels. The ability to utilize lactate during reperfusion is an indicator for postischemic return of contractile function.     

The density of myocardial and pericardial rat mast cells in isoproterenol-induced heart failure

The multifunctional mast cells (MC), located in the myocardium, actively react to the pathology of a cardiovascular system. We investigated MC density in the pericardium and myocardium of rats in intact and experimental heart failure (HF) 24 h and 14, 28, and 60 days after two (at 24 h intervals) injections of Isoproterenol (IP) inducing necrosises in the myocardium. An expressiveness of HF was estimated with the help of ultrasonic scanning of the heart after 28 and 60 days after two IP injections. MC of different degrees of maturity were identified cytochemically on paraffin sections stained with Alcian blue-Safranine. The MC density in the myocardium of intact and experimental rats was relatively low, ranging from 4 to 6 cells/mm², thus the ratio of cells of a different degrees of maturity during HF development was reliably unchanging. In the fibrous layer of pericardium, the MC density was higher than in the myocardium and, for the intact rats, it amounted 48.6 ± 13.0 cells/mm². 24 h to 14 days after IP injections, the MC density in pericardium in contrast to intact sample increased on the average in 1.5 times (P < 0.05) at the expense of increase of density of more differentiated cells stained with Safranine, without density change of less differentiated cells stained with Alcian blue. After 28 days, the MC density in pericardium was 2 times higher than in the intact sample (P < 0.01) and, at the same time, the density of cells of a different maturity degree (P < 0.05) was considerably increased. For 60 days, the MC density and the balance of Alcian-and Safranine-positive cells did not differ reliably from the intact sample. The dynamic of behavior of the MC population of pericardium was corresponding to HF injury on functional parameters. The data obtained indicate the active reaction of MC pericardium on a dysfunction of the myocardium; it stimulates the maturation of resident MCs and the reinforcement of the population at the expense of the migration of cells from the outside, which allows us to propose an intensification of the MC secretory function.     

In vitro cardiac performance in triploid brown trout at two acclimation temperatures

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.     

Notes on the occurrence of the tropical eel Anguilla bicolor bicolor in Peninsular Malaysia, Malaysia

Previous studies indicated that a tropical freshwater eel Anguilla bicolor bicolor occurs in Africa, India, Sri Lanka, Bangladesh, Myanmar, Indonesia and Australia, but an intensive survey has indicated an extended distribution range for the species into Peninsular Malaysia. Thus, A. b. bicolor is a native subspecies of Malaysia.     

犬双心室多点组合同步起搏的心肌力学效应研究

目的 :探讨多点组合同步心室起搏对犬心肌收缩 /舒张力学效应和心脏作功的影响。方法 :12只犬 ,随机进行 5种组合模式的双心室同步起搏 ,并以自身窦性心律状态 (SNR )作为对照。记录各起搏状态下 :左室内压上升和下降最大数率 (±dp/dtmax)、左室松弛时间常数 (τ)、左 /右室游离壁室壁肌张力 (L/RV tensileforce ,L/RV TF)、每搏量 (SV )、左室每搏功 (LVSW )和右室每搏功 (RVSW )等心肌收缩 /舒张力学和心脏作功参数。结果 :双室cHisB LVPL起搏和RVA LVPL起搏的心肌收缩力学参数 +dp/dtmax和L/RV TF较右室双点cHisB RVA起搏增加 ,前两组的心肌舒张力学参数 dp/dtmax也较cHisB RVA起搏增加 ,而τ值较后者缩短。双室三点cHisB RVA LVPL起搏和cHisB RVA LVA起搏的上述各参数均优于双室cHisB LVPL起搏和RVA LVPL起搏。而cHisB RVA LVPL起搏的 +dp/dtmax和L/RV TF均较cHisB RVA LVA起搏增加。cHisB RVA LVPL起搏 dp/dtmax较cHisB RVA LVA起搏提高 6.0 % ,τ值缩短 3 .7%。cHisB LVPL起搏和RVA LVPL起搏的SV、LVSW和RVSW等心室作功参数均较cHisB RVA起搏增加 ,而HisB RVA LVPL起搏的上述心脏作功各参数 ,亦分别较cHisB RVA LVA起搏和cHisB LVPL起搏有不同程度的增加。结论 :双室三点cHisB RVA LVPL组合同     

Extra-cardiac BCAA catabolism lowers blood pressure and protects from heart failure

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Conclusive evidence for panmixia in the American eel

Eels are unique species in the biological world. The two North Atlantic eel species, the American eel (Anguilla rostrata) and the European eel (A. anguilla), occupy a broad range of habitats from the Caribbean to Greenland in the western Atlantic and from Morocco to Iceland in the eastern Atlantic, respectively. North Atlantic eels have a catadromous life cycle, spawning only in the Sargasso Sea and spending the majority of their lives in continental (fresh, brackish and coastal) waters. Despite such a wide distribution range, North Atlantic eels have been regarded as a textbook example of panmictic species. In contrast with the large amount of population genetic studies testing the panmixia hypothesis in the European eel, a relatively modest effort has been given to study the population structure of the American eel. In this issue of Molecular Ecology, Côté et al. ( 2013 ) present the most comprehensive American eel data set to date, which includes samples of different life stages obtained throughout all its distribution range in North America. Results show a total lack of genetic differentiation among samples and provide decisive evidence for panmixia in the American eel.     

Glass eel recruitment, Anguilla anguilla (L.), in a Mediterranean lagoon assessed by a glass eel trap: factors explaining the catches

Although the colonisation of coastal rivers on the Atlantic and Mediterranean coast by glass eels, Anguilla anguilla, has been well studied and understood, the colonisation of lagoons by glass eels is much less known. For the first time in the Mediterranean region, the installation of a glass eel fish-pass in Grau de la Fourcade channels in the Rhône delta enabled us to determine which factors could explain the variations in the catches of glass eel entering the Vaccarès coastal lagoon system. Whatever be the procedure chosen, the results of the model were the same: the temperature, the cumulative water discharge from the channel in the 5 nights before the catch (freshwater lure) and time that the drainage pumps were working explained the glass eel catches in the fish-pass in the Grau de la Fourcade. The tide and the cumulative discharge from the channel for only 3 nights before the catch did not seem to have a significant role in explaining catches. These results show that it is important that the lagoons should continue to receive rainfall runoff from their watersheds so that their water levels are high in winter, and that there is a good colonisation by glass eels as a result of a freshwater lure effect, when strong north winds expel low salinity water to the sea.     

Recent advances in heart regeneration

Although cardiac stem cells (CSCs) and tissue engineering are very promising for cardiac regenerative medicine, studies with model organisms for heart regeneration will provide alternative therapeutic targets and opportunities. Here, we present a review on heart regeneration, with a particular focus on the most recent work in mouse and zebrafish. We attempt to summarize the recent progresses and bottlenecks of CSCs and tissue engineering for heart regeneration; and emphasize what we have learned from mouse and zebrafish regenerative models on discovering crucial genetic and epigenetic factors for stimulating heart regeneration; and speculate the potential application of these regenerative factors for heart failure. A brief perspective highlights several important and promising research directions in this exciting field. Birth Defects Research (Part C) 99:160–169, 2013. © 2013 Wiley Periodicals, Inc.     

The leucocyte enzyme cytochemistry of the Indian eel, Anguilla bicolor bicolor McClelland

Activity of peroxidase, alkaline phosphatase, acid phosphatase, α-naphthyl acetate esterase and naphthol-AS-D chloroacetate esterase in the leucocytes of the Indian eel, Anguilla bicolor bicolor McClelland, was studied. But for some minor differences, the enzyme pattern of the leucocytes, especially neutrophil peroxidase, of the Indian eel closely resembled that of the New Zealand eels, suggesting that the Indian eel is phylogenetically more closely allied to the New Zealand eels than to the European eel.     

Successful TRPV1 antagonist treatment for cardiac hypertrophy and heart failure in mice

Heart failure is becoming a global epidemic. It exerts a staggering toll on quality of life, and substantial medical and economic impact. In a pre-clinical model of cardiac hypertrophy and heart failure, we were able to overcome loss of heart function by administering the TRPV1 antagonist BCTC (4-(3-Chloro-2-pyridinyl)-N-[4-(1,1-dimethylethyl)phenyl]-1-piperazinecarboxamide). The results presented here identify TRPV1 antagonists as new treatment options for cardiac hypertrophy and heart failure.     

Olfactory sensitivity to amino acids in the juvenile stages of the European eel Anguilla anguilla (L.)

Scanning electron micrograph observations of the olfactory mucosa from both unpigmented glass eel(GE)andpigmentedelvers(EL)of the European eel, Anguilla anguilla (L.), revealed the presence of various cell types; amongst these, the ciliated and microvillous ones are likely to possess a chcmosensory function. Recording of underwater electro-olfactograms (EOGs) showed that various amino acids (glycine, L-alanine, L-valine, L-leucine, L-asparagine, L-glutamine and L-methionine) are effective stimulants for the olfactory mucosa. Dose response curves of stimulus concentrations v. EOG amplitudesfit regression linesat both GE and EL stages. Leucine was more stimulatory at the GE than at the EL stage. The stimulatory effect of the other six amino acids tested was similar at both developmental stages. The possible role of olfactory sensitivity in animal behaviour at different developmental stages is discussed.     

Performance of the isolated and perfused working heart of the teleostConger conger: study of the inotropic effect of prostacyclin

Summary An in vitro preparation of the heart of the teleostConger conger, isolated without the pericardium, was set up. The procedure allowed subambient pressures to develop in the perfusion chamber during contraction, mimicking the in vivo situation with the pericardium intact. The ventricle produced a cardiac output of about 15 ml·min^-1·kg wet body weight^-1 at subambient input pressure, and was able to double the stroke work with an increase of preload up to about 0.2 kPa. Using this preparation it was found that prostacyclin has a positive inotropic effect on the atrium and ventricle, but it does not affect the heart rate. Semilogarithmic doseresponse curves of prostacyclin on the atrium are reported, showing a threshold concentration of about 10^-9 M. The isolated and perfusedConger conger heart provides a useful model for a detailed analysis of the action of prostacyclin on myocardial contractility.     

Inter and intra-estuary variability in ingress, condition and settlement of the American eel Anguilla rostrata: implications for estimating and understanding recruitment

The objective of this study was to quantify spatial and temporal variability of anguillid glass eel ingress within and between adjacent watersheds in order to help illuminate the mechanisms moderating annual recruitment. Because single fixed locations are often used to assess annual recruitment, the intra-annual dynamics of ingress across multiple sites often remains unresolved. To address this question, plankton nets and eel collectors were deployed weekly to synoptically quantify early stage Anguilla rostrata abundance at 12 sites across two New Jersey estuaries over an ingress season. Numbers of early-stage glass eels collected at the inlet mouths were moderately variable within and between estuaries over time and showed evidence for weak lunar phase and water temperature correlations. The relative condition of glass eels, although highly variable, declined significantly over the ingress season and indicated a tendency for lower condition A. rostrata to colonize sites in the lower estuary. Accumulations of glass eels and early-stage elvers retrieved from collectors (one to >1500 A. rostrata per collector) at lower estuary sites were highly variable over time, producing only weak correlations between estuaries. By way of contrast, development into late-stage elvers, coupled with the large-scale colonization of up-river sites, was highly synchronized between and within estuaries and contingent on water temperatures reaching c. 10−12° C. Averaged over the ingress season, abundance estimates were remarkably consistent between paired sites across estuaries, indicating a low degree of interestuary variability. Within an estuary, however, abundance estimates varied considerably depending on location. These results and methodology have important implications for the planning and interpretation of early-stage anguillid eel surveys as well as the understanding of the dynamic nature of ingress and the spatial scales over which recruitment varies.     

Morphological and histological changes in the swim bladder during maturation of the Japanese eel

Silver eels Anguilla japonica ( I _G 1·5–3·5) had more developed rete mirabile, gas gland and submucosa than yellow eels ( I _G 0·4–1·5) and the development of swim bladder components increased with sexual maturity only in the early maturation process ( I _G 3·5). These observations indicate that the Japanese eel develops its swim bladder in either the river or shallow sea water and leaves for the open sea after the swim bladder has become adapted to a deeper-sea environment.     

Autonomic control of the heart in the Asian swamp eel (Monopterus albus)

The Asian swamp eel (Monopterus albus) is an air-breathing teleost with very reduced gills that uses the buccal cavity for air-breathing. Here we characterise the cardiovascular changes associated with the intermittent breathing pattern in M. albus and we study the autonomic control of the heart during water- and air-breathing. The shift from water- to air-breathing was associated with a rise in heart rate from 27.7 ± 1.6 to 41.4 ± 2.6 min(-1) and an increase in cardiac output from 23.1 ± 3.0 to 58.7 ± 6.5 mLmin(-1)kg(-1), while mean systemic blood pressure did not change (39.0 ± 3.5 and 46.4 ± 1.3 cmH(2)O). The autonomic control of the heart during water- and air-breathing was revealed by infusion of the β-adrenergic antagonist propranolol and muscarinic antagonist atropine (3 mgkg(-1)) in eels instrumented with an arterial catheter. Inhibition of the sympathetic and parasympathetic innervations of the heart revealed a strong vagal tone on the heart of water-breathing eels and that the tachycardia during air-breathing is primarily mediated by withdrawal of cholinergic tone.     

Cellular phone use does not acutely affect blood pressure or heart rate of humans

A recent study raised concern about increase of resting blood pressure after a 35 min exposure to the radiofrequency (RF) field emitted by a 900 MHz cellular phone. In this randomized, double blind, placebo controlled crossover trial, 32 healthy subjects were submitted to 900 MHz (2 W), 1800 MHz (1 W) cellular phone exposure, and to sham exposure in separate sessions. Arterial blood pressure (arm cuff method) and heart rate were measured during and after the 35 min RF and sham exposure sessions. We evaluated cardiovascular responses in terms of blood pressure and heart rate during controlled breathing, spontaneous breathing, head-up tilt table test, Valsalva manoeuvre and deep breathing test. Arterial blood pressure and heart rate did not change significantly during or after the 35 min RF exposures at 900 MHz or 1800 MHz, compared to sham exposure. The results of this study indicate that exposure to a cellular phone, using 900 MHz or 1800 MHz with maximal allowed antenna powers, does not acutely change arterial blood pressure and heart rate.