Changes in the Rhythmoinotropic Dependence of the Myocardium in Rats with Postinfarction Cardiosclerosis after β1-Adrenoreceptor Blocking

The rhythmoinotropic dependence of the papillary muscles was studied in rats with postinfarction cardiosclerosis after blocking of β₁-adrenoreceptors by concor (7 mg/kg daily). The development of postinfarction cardiosclerosis led to a reduction of the postextrasystolic potentiation and of potentiation induced by periods of rest. Preliminary blocking of β₁-adrenoreceptors stimulated the postextrasystolic contractions and contractions after periods of rest in the myocardium of rats with postinfarction cardiosclerosis. These results suggest that blocking of β₁-adrenoreceptors promotes an improvement of calcium-accumulating function of the cardiomyocyte sarcoplasmatic reticulum in the myocardium of rats with postinfarction cardiosclerosis. Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 147, No. 3, pp. 346–350, March, 2009     

Antiarrhythmic Activity of Phytoadaptogens in Short-Term Ischemia-Reperfusion of the Heart and Postinfarction Cardiosclerosis

A course of treatment (16 mg/kg orally during 5 days) by Aralia mandshurica or Rhodiola rosea extracts reduced the incidence of ischemic and reperfusion ventricular arrhythmias during 10-min ischemia and 10-min reperfusion. Extracts of Eleutherococcus senticosus, Leuzea carthamoides, and Panax ginseng did not change the incidence of ischemic and reperfusion arrhythmias. Chronic treatment by aralia, rhodiola, and eleutherococcus elevated the ventricular fibrillation threshold in rats with postinfarction cardiosclerosis. Ginseng and leuzea did not change this parameter in rats with postinfarction cardiosclerosis. Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 147, No. 3, pp. 303–306, March, 2009     

Inotropic Response of the Myocardium in Rats with Postinfarction Cardiosclerosis Exposed to Extrasystolic Treatment

The inotropic response of the myocardium to extrasystolic treatment was studied on isolated perfused papillary muscles from rats with postinfarction cardiosclerosis. The development of postinfarction cardiosclerosis was accompanied by a decrease in myocardial excitability. The amplitude of extrasystolic contractions in the remodeled myocardium far surpassed the control. However, the amplitude of postextrasystolic contraction did not surpass that in normal contraction—relaxation cycle. Our results suggest that the ability of the sarcoplasmic reticulum in cardiomyocytes to accumulate Ca²⁺ is impaired during postinfarction remodeling.__________Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 139, No. 6, pp. 613–616, June, 2005     

Rhythmoinotropic Myocardial Reactions in Rats with Postinfarction Cardiosclerosis against the Background of Streptozotocin-Induced Diabetes

We studied rhythmoinotropic reactions of the myocardium in rats with postinfarction cardiosclerosis and in rats with postinfarction cardiosclerosis against the background of streptozotocin-induced diabetes. Inotropic myocardial response in rats with postinfarction cardiosclerosis was signifi cantly inhibited after rest periods, while in streptozotocin diabetic rats the rhythmoinotropic myocardial reaction was comparable with the reaction of intact myocardium. The combination of postinfarction cardiosclerosis and diabetes paradoxically contributed to preservation of contractile function of the myocardium in rats.     

Opioid receptors and heart resistance to arrhythmogenic factors

We present detailed data on the role of central and peripheral opioid receptors in the regulation of heart resistance to arrhythmogenic factors. Stimulation of peripheral δ₂- and κ₁-receptors increases heart resistance to the arrhythmogenic effect of acute ischemia and reperfusion. Activation of peripheral μ- and δ₁-opioid receptors improves electrical stability of the heart in animals with postinfarction cardiosclerosis. Possible mechanisms for opioidergic regulation of heart resistance to arrhythmogenic factors are discussed. Translated fromByulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 138, No. 8, pp. 124–131, August, 2004 This work was supported by the Russian Foundation for Basic Research.     

Content of Fibronectin and Glycosaminoglycans in Blood Serum of Rats with SiO2-Induced Inflammation after Radon-Containing Water Bath

In animals with SiO₂-induced inflammation, exposure in radon-containing water promoted normalization of fibronectin content on days 3 and 10 and reduced the content of glycosaminoglycans on days 3 and 20 compared to the corresponding values in intact animals and rats with SiO₂-induced inflammation not exposed to radon. Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Suppl. 1, pp. 32–34, 2008     

Lipid composition of rat somatic nerves under the effect of damaging factors

Ligation of the sciatic nerve in rats led to reversible decrease in excitability and changes in lipid composition of myelinated nerve fiber: increase in the content of lysophosphatidylcholine, lysophosphatidylethanolamine, and free fatty acids and phospholipase A₂ activity. Xymedon and laminin accelerate nerve regeneration and restore its lipid composition. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 142, No. 8, pp. 155–157, August, 2006     

Negative regulation of caspase-3 expression in the neonatal cerebral cortex by α<Subscript>2A</Subscript>-adrenoceptors

Antisense oligonucleotide to α_2A-adrenoceptors increased the levels of mRNA (reverse polymerase chain reaction) and protein for a key executioner protease of apoptosis caspase-3 (immunoblotting assay) in the cerebral cortex of newborn rats. The relationship between the observed effect and low expression of α₂-adrenoceptors was confirmed by the possibility of correcting this phenomenon by clonidine (stimulator of α₂-adrenoceptors). __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 143, No. 3, pp. 244–246, March, 2007     

Adaptation of the cardiovascular system to postinfarction cardiosclerosis in rats with congenital adrenoreactivity of the myocardium

Three months after myocardial infarction the severity of heart failure and size of postinfarction scars in August rats with inherently reduced adrenoreactivity of the myocardium were similar to those in Wistar rats. The mortality rate in August rats was 2.5-fold lower than in Wistar rats. During the postinfarction period, myocardial adrenoreactivity in August rats remained lower, while the efficiency of cardiac function was 62% higher than in Wistar rats. The incidence of epinephrine-induced arrhythmias in August rats was much lower than in Wistar rats. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 144, No. 12, pp. 624–628, December, 2007     

Structural characteristics of cardiomyocytes in the right atrium of NISAG rats

Electron microscopy and stereomorphometric analysis of hypertrophic cardiomyocytes in the right atrium of NISAG rats revealed signs of activation of biosynthetic processes: increased relative volume of euchromatin (compared to Wistar rats), high density of nuclear pores, presence of large numerous Golgi complexes, and well-developed endoplasmic reticulum. The numerical density of secretory granules in the cytoplasm of cardiomyocytes in NISAG rats significantly surpassed that in Wistar rats. However, these granules in NISAG rats were smaller than in Wistar rats. The presence of numerous secretory granules and increased ratio of forming and dissolving structures suggest that this pool is characterized by high turnover rate,i.e., intensive synthesis and rapid elimination (consumption) of natriuretic peptide. Hypertrophy and hyperactivity of endocrine function in atrial cardiomyocytes of NISAG rats can be considered as a compensatory reaction to hypertension. Translated fromByulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 138, No. 7, pp. 4–8, July, 2004     

Effect of serum from cardiovascular patients on catalytic activity of secretory phospholipase A2 (IIA)

Incubation of patients’ serum catalytically active by type IIA secretory phospholipase A₂ (SP-IIA) with serum containing the enzyme in a high concentration but exhibiting no catalytic activity in 1:1 volume ratio led to a significant inhibition of SP-IIA catalytic activity. Donor and patient sera with low levels of SP-IIA had no effect on the serum with SP-IIA activity under these conditions. However, the increase in the content of patients’ serum with a low level of SP-IIA in the incubation mixture to 1:2 (v/v) and of donor serum to 1:3 (v/v) also led to blockade of SP-IIA catalytic activity. These results indicate that human serum contains an SP-IIA inhibitor and its concentration decreases significantly in sera with SP-IIA activity. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 142, No. 11, pp. 525–527, November, 2006     

Der Einfluß desP A CO 2 auf die Wirkung der Sinusnervenreizung bei intakten und ausgeschalteten Nn. vagi

Summary In rabbits rebreathing oxygen one carotid sinus nerve was stimulated repeatedly by electrical stimuli of constant intensity, both before and after inactivation of vagi by cold blocking or sectioning. In animals with intact vagi the reflex hyperpnea elicited by the nerve stimulation decreased only slightly with increasing hypercapnia. After inactivation of the vagi the stimulatory effect was, at normalP _{A CO 2}, mostly greater than in the intact condition. But with increasing hypercapnia the decrease of the reflex hyperpnea was generally steeper than in the intact preparation, sometimes reaching even lower values than before inactivation. The depressant effects of the stimulation on systemic blood pressure and heart rate were not distinctly changed by the increase ofP _{A CO 2}, neither with intact nor with inactivated vagi. It is concluded that the ventilatory effect of chemoreceptor afferents is modified both by centralP _{CO 2} and by vagal afferents.

Mit Unterstützung der Deutschen Forschungsgemeinschaft (Wi 165).     

M<Subscript>3</Subscript> cholinergic receptors are involved in postnatal development of cholinergic regulation of cardiac activity in rats

We studied the role of M₃ cholinergic receptors in the regulation of cardiac activity in rats during early postnatal ontogeny in vivo. Blockade of M₃ cholinergic receptors in 20-week-old animals increased heart rate and decreased blood pressure. In rats aging 8, 6, and 3 weeks, blockade of M₃ cholinergic receptors had little effect on R-R interval, but unexpectedly increased it in 1-week-old animals. It can be hypothesized that tonic inhibitory effect of the vagus nerve in adult rats is realized through M₃ cholinergic receptors of the heart. The decrease in heart rate during blockade of M₃ cholinergic receptors in 1-week-old rats was probably related to specific innervation of the heart in animals of this age. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 144, No. 8, pp. 135–137, August, 2007     

Involvement of oxygen radicals and phospholipase A2 in acute pancreatitis of the rat

Summary The purpose of this study was to assess the involvement of oxygen radicals and phospholipase A₂ in acute pancreatitis. Acute pancreatitis was induced in rats by the CCK-analogue cerulein (5 µg/kg · h) for 30 min, 3.5 h, and 12 h. At the end of the infusion, serum enzymes and the lipid peroxidation products conjugated dienes and malondialdehyde in the tissue were measured. Moreover, tissue samples underwent lightmicroscopical examination. After 3.5 h cerulein, an interstitial edema and a beginning accumulation of granulocytes in the pancreatic gland is observed. These changes are aggravating within 12 h, leading to tissue necrosis and migration of the granulocytes into the tissue. Concomitantly amylase and lipase increase by 15 and 35 times, respectively. Conjugated dienes and malondialdehyde increase already after 30 min cerulein and reach their highest levels after 3.5 h cerulein. At the same time the tissue activity of phospholipase A₂ is elevated three fold. Rats were treated with superoxide dismutase and catalase before cerulein infusion. Treatment significantly prevents tissue necrosis, granulocyte accumulation, and edema formation. The enhanced activity of phospholipase A₂, however, is unaffected by the treatment. Oxygen radicals seem to be instrumental in the development of the disease.     

Effects of chlorpromazine on the enzymatic and toxic properties of the most basic phospholipase A2 fromVipera russelli snake venom

The effect of chlorpromazine on various biological activities of phospholipase A₂ VRV-PL-VIII_a fromVipera russelli snake venom was investigated. The drug inhibited the in vitro phospholipase A₂ activity of the enzyme by 55%. The ID₅₀ was found to be 1.15 µM. Increasing substrate concentration relieved the inhibition of phospholipase A₂ activity by the drug indicating probable interaction with the substrate. The drug totally quenched the fluorescence intensity of the enzyme. Chlorpromazine increased the LD₅₀ of the enzyme by 1.6 fold. The drug also inhibited hemolytic and anticoagulant potencies but failed to inhibit edema inducing activity and myotoxicity of the enzyme.     

Effect of atmospheric ammonia on mortality rate of rats with barbiturate intoxication

Ammonia inhalation (0.84–1.07 mg/liter, 3 h) was accompanied by a 65% increase in ammonia concentration in mixed blood of intact rats. This treatment did not cause death of intact animals, but potentiated the lethal effect of sodium thiopental and inhibited external respiration and O₂ consumption in animals. The resistance of rats to the lethal effect of barbiturate tended to decrease under conditions of experimental hyperammonemia induced by intraperitoneal injection of ammonium acetate in a nonlethal dose (6 mmol/kg). Our results indicate that potentiation of the toxic effect of barbiturates by atmospheric ammonia is related to its resorptive effects. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 143, No. 6, pp. 634–636, June, 2007     

Extracellular phospholipase A2 detected at inflamed sites in rats does not originate from platelets

Extracellular phospholipase A₂ activity has been detected in caseinate-induced peritoneal fluid in rats. We studied the source of this extracellular phospholipase A₂ in platelet-poor rats which had been pretreated with an intravenous injection of rabbit anti-rat platelet serum. In these rats, the increase in the peritoneal fluid extracellular phospholipase A₂ level at the inflamed sites was almost identical to that observed in control rats, although platelet numbers in peripheral blood were decreased markedly. This observation suggests that extracellular phospholipase A₂ in the peritoneal cavity is not derived mainly from platelets.This work was supported in part by Grants-in-Aid for Scientific Research (Nos. 62870093 and 63480490) from the Ministry of Education, Science and Culture of Japan.     

Effects of hormones on phospholipase A2 activity in rat skin

We studied the effects of hydrocortisone, progesterone, estradiol, and testosterone on phospholipase A₂ activity in plasma and lysosomal membranes of rat dermis and epidermis. The dermal enzyme was more sensitive to estradiol, while epidermal to testosterone. The effects of progesterone and hydrocortisone were mediated by lipocortin-like protein, while estradiol and testosterone directly by modulated phospholipase A₂ activity Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 129, No. 1, pp. 70–72, January, 2000     

Inotropic reaction of myocardium rats with postinfarction and diabetic remodeling on extrasistolic influences

Studied inotropic reaction papillary muscles of rats with postinfarction and diabetic remodeling on extrasistolic influences. It was found, that excitability of myocardium rats raises at a diabetes induced streptozotocin. Postextrasistolic contraction of myocardium rats with postinfarction cardiosclerosis it was considerably oppressed, and rhythmoinitropic reaction of myocardium rats was comparable to reaction of intact myocardium at a diabetes induced streptozotocin. The combination postinfarction and diabetic influence is paradoxical promoted preservation postextrasistolic potentiation of myocardium rats.     

Combined administration of NAN-190 and 17β-estradiol abolishes the amnesic effect of scopolamine in middle-aged ovariectomized rats

Chronic combined administration of 5-HT_1A receptor antagonist NAN-190 and 17β-estradiol improved conditioned passive avoidance performance in middle-aged ovariectomized rats with scopolamine-induced amnesia. Our results suggest that the ovarian hormonal, cholinergic, and serotoninergic systems play a role in age-related cognitive disturbances under conditions of hypoestrogenic syndrome. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 142, No. 7, pp. 90–93, July, 2006