Changes in EEG and higher nervous activity of rats during cerebral anti-ischemic protection by acelysin]

The water-soluble aspirin (acelysin) has been used as an anti-ischaemic protector when injected in the dose of 150 mg/kg 30 min before ischaemia. The EEG has been registered during the whole period of experiment and the total EEG power index has been calculated. The higher nervous activity has been evaluated during analysis of rat's abilities for elaboration of conditional reflex of an active escape reaction in Y-labyrinth. The results have demonstrated the complete rehabilitation and restoration of brain functional activity 8 days after endurance of brain ischaemia under protection of acelisin.     

Electrical activity in frog heart after isoproterenol

The electrical and mechanical activity of myocardial strips from Rana pipiens after injection of isoproterenol (ISO) was studied during cyanide anoxia. Compared to controls, isometric tension was more depressed, resting tension more increased and action potential duration extremely reduced when ISO-damaged heart was exposed to cyanide anoxia. The same results could be obtained after inactivation of the fast Na+-system, when the resting membrane potential was held at -50 mV in elevated Ko+. These alterations are explained by an increase of Cai2+ since cyanide is known to release intracellularly stored Ca2+. Pretreatment with ISO may possibly increase the amount of releasable Ca2+.     

心肌细胞间的电耦联

心脏是由无数个独立的心肌细胞通过缝隙连接形成的一个功能性合胞体。心肌细胞间的电耦联是心脏“全或无”性动作电位传导和机械收缩的先决条件。缺氧、缺血、药物、细胞内外离子浓度的改变以及激素等因素可直接或间接地影响心肌细胞间的电耦联,从而导致心脏功能的改变。     

The anti-ischemic action of a perfluorocarbon emulsion (PFCE) on the canine myocardium

On the 60th minute after inducing the acute ischemia in the canine myocardium by the occlusion of the left anterior descending coronary artery, the animals were intravenously infused with perfluorochemical emulsion (PFCE), its salt composition (SC) or 4% surface-active substance (SAS), proxanol, at a dose of 10 ml/kg. Two hours after infusion, the occlusion was removed (reperfusion). The arterial pO2 was maintained at 120 mm Hg. Analysis of the blood flow, oxygen supply, acid-alkali balance, ECG, as well as creatine phosphokinase activity, measured in the ischemic area, has shown that PFC emulsion is capable of reducing ischemic damage and preventing reperfusion-induced myocardium injury. Thus, the presence of perfluorochemicals in the PFC emulsion is an essential factor in its ischemia-protective effect.     

Electrical and mechanical activity of isoproterenol-damaged frog heart

The electrical and mechanical activities of myocardial strips from Rana pipiens were studied in the steady state at various stimulation frequencies and after a period of rest. The temperature of the bath was varied between + 12 and 35 degrees C. Normal myocardium was compared with that damaged by isoproterenol (ISO). The percentage change of action potential durations (APD50) and isometric force (P) was similar in ISO-damaged and control hearts at various bath temperatures with steady state stimulation rates between 20 and 100/min. At low stimulation rates (3-6/min) the prolongation of the action potential (AP) was more pronounced and the P-decrease was less in ISO-damaged myocardium compared to controls. These differences became more apparent at low bath temperatures. After 10 min of rest, APD50-90 was significantly prolonged in ISO-damaged heart and P was increased by a factor of 2 compared to controls (stimulation rate 20/min). Steady state values, on the other hand, were nearly the same in both groups. These findings are interpreted as indicating a temperature or ISO-dependent increase of electrogenic trans-sarcolemmal Ca2+-uptake during low frequency, or post-rest stimulation, either directly by an increase of the slow inward current (Isi), or indirectly by decreased K+-permeabilities.     

Identification, biological activity, and mechanism of the anti-ischemic quinolone analog

The quinolone analog SQ-4004 has been identified as a potentially excellent anti-ischemic agent, which exhibited highly potent efficacy in reducing infarct volume size in vivo rat MCAO model (32.1% at 0.01mg/kg) and potent cardioprotective effect at myocardial infarction in vivo model (26.6% at 0.01mg/kg) while it exhibited highly reduced anti-bacterial activity. The mechanistic study revealed that the anti-ischemic activity might exert via an anti-apoptotic pathway, which implies its therapeutic uses against the ischemic cell injuries including ischemic stroke and ischemic heart disease.     

Mitotic activity of the myocardium in early ontogenesis of rabbits after minor mechanical injury to the heart

The data are provided on proliferative activity of myocytes in rabbit embryos and neonates. In rabbit embryos, in which myocardial regeneration is effected at the cellular level, mitoses of myocytes are largely important for myocyte proliferation. In rabbit neonates which do not show any complete regeneration of the myocardium, mitoses of myocytes are of primary importance for myocardial polyploidy. Minor mechanical injury to rabbit myocardium in early ontogenesis contributes to activation of the processes of hear muscle differentiation.     

Afferentation of the heart in pathological states of the myocardium

The state of afferent connections between sinoatrial node zone (SNZ) in the normal and affected myocardium (reversible ischemia, necrosis) and rostral parts of the brain cortex (RPC) was studied with the help of evoked potentials in acute experiments on cats. Interruption of afferent connections (SNZ-RPC) during reversible ischemia and experimental myocardial necrosis of the right ventricle was revealed. Ultramicroscopic data of SNZ studies as well as electrophysiologic changes registered in RCP during irritation of the peripheral part of the right vagus nerve and local application of GABA on SNZ suggest possible interruption of cardiac afferentation at the level of SNZ due to the mechanism of presynaptic inhibition.     

Collagenase activity in the normal rat myocardium

Summary Fibrillar collagen in the myocardium provides a supportive framework for myocytes and capillaries. Disruption of this organized framework has been observed in certain pathological states. Collagen degradation is primarily mediated by the specific enzyme collagenase, which has been found to exist in various tissues including the myocardium. In this report we describe a method that detects collagenase activity in sections of cardiac tissue. This method is on the basis of degradation of collagen by collagenase on one hand and the visualization of disrupted collagen fibers by immunofluorescence on the other. Frozen rat heart secctions were incubated under optimal conditions for collagenase activity (37°C in the presence of 0.1 M calcium at pH 7.4) for 24 h and 48 h. Subsequently, immunofluorescence staining with antibody to type I collagen was performed and the collagenous structures were visualized by immunofluorescence light microscopy. As control, untreated rat heart sections and sections incubated in the absence of calcium were similarly treated with antibody. After the 24 h of incubation, we found no change in the structural integrity of collagen fibers. Marked disruption of the type I collagen fibers was observed 48 h after incubation. No evidence of collagen fiber disruption was found in control sections. Experiments with exogenous collagenase resulted in similar collagen fiber disruption in the frozen rat heart sections. We conclude that the disruption of collagen type I fibers after 48 h of incubation, under optimal conditions for collagenolytic digestion, is. the result of collagen degradation by intrinsic collagenase of the myocardium.     

Electrical and mechanical activity in heart tissue of flounder and rainbow trout during acidosis

1. Twitch force and voltage across the sarcolemma were measured in heart tissue of flounder and rainbow trout. 2. For the trout heart, hypercapnia was followed by a loss of force and an action potential prolongation. 3. This was also observed for the flounder heart, but only initially. 4. About 5 min after the onset of hypercapnia, an increase in force and a shortening of the action potential occurred in the flounder heart. 5. After about 30 min of hypercapnia a decrease in force and a prolongation of the action potential slowly appeared. 6. These results can be interpreted in terms of a species-dependent effect of acidosis on the cellular Ca2+ handling and the influence of intracellular Ca2+ on the action potential.     

Electrical activity of cultured cells of the guinea pig heart. Comparison with the rat]

For the first time, action potentials were recorded with the use of microelectrodes from myocardial cells beating spontaneously which were obtained by trypsination of guinea-pig embryonic hearts. 4-5 weeks old embryos have been found most suitable for such experiments. The development of cultures and the recordings obtained were compared to those observed in rat hearts under the same experimental conditions. These results showed that inspite of the known physiological differences between adult rat hearts and adult guinea-pig hearts, the cardiomyoblasts cultured under the same conditions possess common features relating to the repolarization phase of action potential, specially a lack of the plateau.