Levosimendan in Acute and Advanced Heart Failure: an Expert Perspective on Posology and Therapeutic Application.

Levosimendan, a calcium sensitizer and potassium channel-opener, is widely appreciated by many specialist heart failure practitioners for its effects on systemic and pulmonary hemodynamics and for the relief of symptoms of acute heart failure. The drug's impact on mortality in large randomized controlled trials has been inconsistent or inconclusive but, in contrast to conventional inotropes, there have been no indications of worsened survival and some signals of improved heart failure-related quality of life. For this reason, levosimendan has been proposed as a safer inodilator option than traditional agents in settings, such as advanced heart failure. Positive effects of levosimendan on renal function have also been described. At the HEART FAILURE 2018 congress of the Heart Failure Association of the European Society of Cardiology, safe and effective use levosimendan in acute and advanced heart failure was examined in a series of expert tutorials. The proceedings of those tutorials are summarized in this review, with special reference to advanced heart failure and heart failure with concomitant renal dysfunction. Meta-analysis of clinical trials data is supportive of a renal-protective effect of levosimendan, while physiological observations suggest that this effect is exerted at least in part via organ-specific effects that may include selective vasodilation of glomerular afferent arterioles and increased renal blood flow, with no compromise of renal oxygenation. These lines of evidence require further investigation and their clinical significance needs to be evaluated in specifically designed prospective trials.

Incidence of chromosomal abnormalities in the presence of fetal subcutaneous oedema, such as nuchal oedema, cystic hygroma and non-immune hydrops.

INTRODUCTION: The authors investigated the incidence of chromosomal abnormalities in subcutaneous oedema detected in the fetus by intrauterine ultrasonography. MATERIAL AND METHOD: In the 10-year period, intrauterine karyotyping was performed in pregnancies with positive ultrasound findings for subcutaneous oedema, such as nuchal oedema, cystic hygroma and non-immune hydrops. RESULTS: Intrauterine karyotyping in fetal subcutaneous oedema was carried out in 434 cases. The chromosomal investigation was made in nuchal oedema in 374 cases, in 120 patients the chromosomal examination was made in the first trimester because of nuchal translucency, and in 254 cases in the second trimester because of nuchal thickening. Cystic hygroma cases (27 patients), non-immune hydrops cases (20 patients), and combined cases of non-immune hydrops and cystic hygroma (13 patients) were investigated separately. In nuchal oedema, pathological karyotypes were detected in 8.33% in the first trimester and in 5.51% in the second trimester. Chromosomal abnormality was found in 48.15, 20, and 53.8% in cystic hygroma, non-immune hydrops, and combined occurrence of non-immune hydrops and cystic hygroma, respectively. Considering all of the changes accompanied by subcutaneous oedema, 50, 25 and 18.75% of the pathological karyotypes was X-monosomy, trisomy 18 and trisomy 21, respectively. DISCUSSION: It was important to distinguish nuchal oedema and cystic hygroma, and in the case of non-immune hydrops, it was also important to discuss cases with or without cystic hygroma separately. During the investigations, cases of non-immune hydrops with or without cystic hygroma were evaluated as separate categories. CONCLUSIONS: The authors emphasize the differentiation of the various types of subcutaneous oedema and the importance of precise information about the risks, provided during genetic counselling.

Whole blood chemiluminescence response in broiler chickens on different experimental diets and challenged with Clostridium perfringens.

UNLABELLED: 1. OBJECTIVES: To validate the whole blood chemiluminescence (WBCL) assay in chickens, a simple and rapid method of measuring production of reactive oxygen species by circulating polymorphonuclear (PMN) leukocytes. To determine the physiological response and innate immune response associated with oral challenge with Clostridium perfringens in broiler chickens under different nutritional conditions. 2. In Experiment 1, birds were orally challenged with C. perfringens 1. type A or sham-challenged saline on days 14-21 post-hatch and fed protein-balanced diets containing 160 or 180 g crude protein/kg and 0.98 or 1.75% glycine in a 2 x 2 x 2 factorial arrangement of treatments. 2. Challenged birds had higher WBCL responses and more severe intestinal lesions than unchallenged birds. Birds fed diets containing 1.75% glycine had more intestinal lesions than those fed 0.98% glycine. 3. In Experiment 2 birds were fed protein-balanced diets containing 0.76, 2.10, 3.43 or 4.77% glycine. The birds fed 0.76% glycine diet had lower WBCL responses compared to birds fed the other three diets. Intestinal lesions were worse in the birds fed the highest, 4.77% glycine diet than in those fed the 0.76 or 2.10% glycine diets. 4. We conclude that the WBCL assay is a practical and sensitive means of assessing innate immune function in birds. The results suggest that both bacterial challenge and glycine content of chickens' diet influence their lesion scores and innate immune function.

Lean birds in the city: body size and condition of house sparrows along the urbanization gradient.

1. Urbanized habitats differ from natural ones in several ecological features, including climate, food availability, strength of predation and competition. Although the effects of urbanization on avian community composition are well known, there is much less information about how individual birds are affected by these human-generated habitat differences. 2. In this study we investigated the relationships between the morphological characteristics and the degree of habitat urbanization in house sparrows, Passer domesticus (Linne 1758) . We collected data for more than 1000 non-breeding adult birds in Hungary between 1997 and 2006, from seven sites including farmlands, suburban areas and city centres. 3. We found that the body mass, tarsus length and body condition of free-living sparrows differed among the sites: birds in more urbanized habitats were consistently smaller and in worse condition than birds in more rural habitats. A composite measure of habitat urbanization (based on building density, road density and vegetation cover) explained over 75% of variance between sites in the studied traits, after we controlled for the effects of sex, year, season and time of capture. 4. The difference in body mass between rural and urban sparrows was significant when birds were kept in aviaries under identical conditions, with constant ad libitum food availability. It is therefore unlikely that the reduced body size and condition of urban sparrows are a consequence of reduced access to food for adults (e.g. due to strong competition), or their short-term responses to high food predictability (e.g. by strategic mass regulation). 5. We suggest that habitat differences in nestling development or adaptive divergence of sparrow populations due to distinct environmental conditions (such as differing predation pressure) may account for the differences along the urbanization gradient.

Prenatal diagnosis of abnormal course of umbilical vein and absent ductus venosus--report of three cases.

An abnormal course of the umbilical vein is a rare anomaly. Its association with the congenital absence of the ductus venosus is common. We found 3 cases of an abnormal course of the umbilical vein and an absent ductus venosus. In 2 of these cases, the umbilical vein turned down and continued in the internal iliac vein, and no ductus venosus was found. One of these pregnancies was terminated. From the continued pregnancy a growth-retarded baby was born. At follow-up examinations, mild microcephaly, mildly elevated levels of ammonia, delayed speech and mild muscular hypotonia were found. In the third case, the umbilical vein turned up from the level of umbilical ring and the anterior of the liver above the diaphragma and connected directly into the right atrium. Associated complex congenital heart malformations - transposition of the great arteries, and ventricular septal defect - were diagnosed prenatally. In the umbilical vein from the placenta to the umbilical ring, the flow was low velocity continuous; from the umbilical ring to the right atrium, the flow was biphasic high velocity (90 cm/s). Such an elevated blood flow could be a sign of increased cardiac preload. The long-term neurological follow-up of babies with prenatally diagnosed venous malformations is necessary.

Variation of indoor radon progeny concentration and its role in dose assessment.

Instantaneous measurements of equilibrium equivalent concentration of radon (EEC(Rn)) were taken over a period of 1 year in 2004 in a typical house at Amritsar city, located in the northwest part of India. A method based on absolute beta counting subsequent to grab aerosol sampling was used. During that year, EEC(Rn) varied between 1.56B qm(-3) and 22.77B qm(-3) with average value of 8.76Bb qm(-3). EEC(Rn) decreased with the transition from winter to summer and vice versa, having a negative correlation with outdoor temperature. The use of mechanical ventilation, under normal living conditions during summer, caused an extra decrease in the concentrations. The variations with temperature and mechanical ventilation are discussed. Some major issues related to the uncertainties in dose calculations caused by the lack of knowledge of equilibrium factor and ignoring the effect of life style on the radon and its progeny concentrations are discussed.

Analysis of perioperative morbidity according to whether the uterine cavity is opened or remains closed during abdominal myomectomy--results of 423 abdominal myomectomy cases.

UNLABELLED: For women who desire pregnancy or who wish to retain their uterus, myomectomy is the standard approach for the treatment of fibroids. Abdominal myomectomy seems to be the best choice when there are large subserosal or intramural fibroids (> 5-7 cm), or submucosal fibroids > 3 cm or when multiple fibroids (> 3) are to be removed. When submucosal myomas are present or multiple fibroids are to be removed, opening the uterine cavity during the surgical procedure is more likely to happen. There is lack of published evidence about whether there is any difference in perioperative morbidity and management of those cases where the uterine cavity is opened during the surgical procedure compared with those where the uterine cavity remains closed. METHODS: We undertook a retrospective review of 423 abdominal myomectomies via either an opened or closed uterine cavity. As a primary outcome we assessed the overall perioperative morbidity rate and as a secondary outcome we compared the necessity of pre and postoperative transfusions, intraoperative bleeding, febrile morbidity, unintended surgical interventions, life-threatening events, need for relaparotomies and duration of hospital stay between the opened and non opened uterine cavity groups. RESULTS: The overall perioperative morbidity rate was significantly higher in those cases where the uterine cavity was opened during surgery; however the difference was caused only by the increased risk of intraoperative bleeding. All the other variables, such as febrile morbidity, number of relaparotomies, unintended surgical procedures and life-threatening events did not differ between the two groups. CONCLUSION: Although there is an increased risk of intraoperative bleeding it seems that entering the uterine cavity during abdominal myomectomy can be considered as safe a procedure as in those cases where the uterine cavity remains closed.

High frequency of methylenetetrahydrofolate reductase 677TT genotype in Hungarian HELLP syndrome patients determined by quantitative real-time PCR.

Our aim was to determine the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism in hypertensive disorders during pregnancy. We conducted our experiments on isolated DNA samples of 73 healthy pregnant, 101 severe pre-eclamptic and 63 HELLP syndrome women in this study. The MTHFR C677T polymorphism was determined by quantitative real-time PCR method. A significantly higher number of the TT genotype (25.4%) was found in the HELLP syndrome group compared to the healthy (8.2%) and severe pre-eclamptics group (8.9%) (P=0.03). The frequency of the mutant T allele was found to be 45.2% of HELLP syndrome, whereas it was 32.2% of the healthy pregnant (P=0.03) and 30.2% (P=0.008) of the severe pre-eclamptic patients. In the HELLP group a high frequency of eclampsia was observed (12.6%) and among them 75% had the MTHFR C677T mutation.

Novel mutation in OTC gene causes neonatal death in twin brothers.

Ornithine transcarbamylase (OTC) deficiency is the most common inborn error of the urea cycle. OTC locus is located in the short arm of X-chromosome. Authors report a case of a woman who gave birth to monozygotic male twins who later died because of severe neonatal-onset hyperammonaemic encephalopathy caused by a novel mutation of OTC gene. Post-mortem liver biopsy was taken from the second twin; afterwards, blood was drawn from the mother for examination. DNA sequence data showed that the mother was a carrier of the same novel mutation that was previously detected in the case of her son. In OTC deficiency, detection of female carriers is important for genetic counselling and eventual prenatal diagnosis.

Spinal anesthesia for cesarean section in a woman with Kartagener's syndrome and a twin pregnancy.

Kartagener's syndrome is an inherited disease characterized by a triad of symptoms: bronchiectasis, situs inversus and sinusitis resulting from defective cilial motility. There are few reports in the literature regarding the optimum anesthetic technique in patients with Kartagener's syndrome. The main anesthetic considerations are related to the respiratory system and increased risk of infection. We report the case of a woman with Kartagener's syndrome and a twin pregnancy conceived by in-vitro fertilization-embryo transfer, who underwent cesarean section under spinal anesthesia. Despite recurrent pulmonary problems, the twin pregnancy resulted in a successful outcome. This was facilitated by a close working relationship between the obstetrician, anesthesiologist and patient.

Natural origins of off-flavours in fish related to feeding habits.

The objective of our study was to survey the accumulated 2-methylisoborneol (MIB) and geosmin (GSM) in fillets of five important farmed fish species in Hungarian aquaculture in relation to MIB and GSM concentrations in water and sediment in the aquatic systems where they were raised: (the planktivorous silver carp (Hypophthalmichthys molitrix), the herbivorous grass carp (Ctenopharyngodon idella), the bottom-feeding omnivorous common carp (Cyprinus carpio), the omnivorous tilapia (Oreochromis niloticus) and the carnivorous African catfish (Clarias gariepinus)). Water, sediment and fish samples were collected from different experimental aquatic systems which included a combined aquaculture-algae (CAA) system, effluent-fed fishponds, a pond recycling system and a traditional fishpond. MIB and GSM contents were extracted with distillation-headspace solid-phase-microextraction (SPME) and extracts analysed by GC-MS. Results showed that off-flavour contents in fish fillets were related to the feeding habits of the studied fish species. Higher GSM concentrations were found in the fillet of bottom-feeding common carp than in the silver carp or African catfish in all studied aquatic systems. Usually, low GSM concentrations were detected in the water of fishponds but sometimes the levels of this odour compound in carp fillet were well above the limits of human detection. This suggests that the off-flavour tainting of common carp may originate from the sediment or benthic algallactinomycete sources. Negligible MIB levels were found in all samples in all of the studied aquatic systems.

Chronic obstructive pulmonary disease and oxidative stress.

The respiratory tract as the main entrance for various inhalative substances has great potential to generate reactive species directly or indirectly in excess. Thus, heavy smokers are at high risk for development, impairment and failed response to treatment of chronic obstructive pulmonary disease (COPD). The article is an update regarding the influence of reactive oxygen (ROS) and nitrogen (RNS) species on COPD; however, we do not intend to describe ROS and RNS actions on the entire lung tissue. Here, we focus on the airways, because in human most of the described effects of ROS and RNS species are measured on respiratory epithelial cells obtained by bronchoscopy. ROS and RNS species are physiological compounds in cells and risk factors for several respiratory diseases. In general, both kinds of species are thermodynamically stabile, but their reaction behaviors in cellular environments are very different. For example, the life times of the superoxide anion radical range from micro/milliseconds up to minutes and even hours in in-vitro model systems. Oxidative stress by cigarette smoke was investigated in detail by the authors of this article. In addition, original studies by the authors on the amount of fine particulate matter and trace elements in lung biopsies after defined inhalation indicate a distortion of the equilibrium between oxidants and antioxidants. We also try to present some modern views with respect to genomic medicine for future therapeutic perspectives, although this is an upcoming sector of COPD therapy.

Hypogastric artery ligation for intractable pelvic hemorrhage.

OBJECTIVE: To assess the outcomes of bilateral hypogastric (internal iliac) ligation performed to control intractable pelvic hemorrhage and avoid hysterectomy. METHODS: A review of indications and outcomes for 117 cases of bilateral hypogastric artery ligation over 15 years (1990-2004). RESULTS: Apart from a slight lesion to the hypogastric vein, no complications were observed. Hemorrhage was effectively controlled in all 37 obstetric cases. In 13 of these cases, the uterus was preserved even when there was cervical pregnancy, placenta previa, placental abruption, uterine atony, and uterine rupture, and 4 women were delivered of mature infants. Hemorrhage was effectively controlled in 41 of 80 gynecologic cases. Prophylactic reduction of pelvic blood flow was the indication for the procedure in 39 cases, 5 of whom involving Jehovah's Witnesses adverse to blood transfusion. The uterus was preserved in only a few of the 41 controlled cases, but one woman (so far) was delivered of a mature infant. CONCLUSION: Hypogastric artery ligation was found to be indicated if (1) life-threatening pelvic hemorrhage could not be controlled by conservative methods; (2) prophylactic reduction of pelvic blood flow was needed to prevent anticipated hemorrhage; and (3) preservation of reproductive function was desired. The procedure was found to be safe and usually effective and should be taught during obstetric and gynecologic training.

Nerve-sparing radical hysterectomy for stage IA2-IIB cervical cancer: 5-year survival of 501 consecutive cases.

OBJECTIVE: The purpose of this study was to assess the 5-year survival and morbidity in cases with radical hysterectomy and pelvic lymphadenectomy with pre- and postoperative irradiation performed to treat Stage IA2-IIB cervical cancer. METHODS: During a 10(1/2)-year period between July 1990 and December 2000, 501 consecutive radical hysterectomies with bilateral pelvic lymphadenectomy were performed by the same gynecological surgeon in Stage IA2, IB, IIA and IIB cervical cancer. The patients were treated by pre- and postoperative irradiation as well. RESULTS: Apart from recurrence, perioperative complications were minimal with no long-term morbidity. The absolute 5-year survival rates for the patients in Stage IA2, IB1, IB2, IIA and IIB were 94.4%, 90.7%, 84.1%, 71.1%, and 55.4%, respectively. The respective 5-year survival rates for patients without or with lymph node metastasis were 94.5% and 33.3% in Stage IB2, 81.7% and 48.7% in Stage IIA and 70.2% and 36.5% in Stage IIB, respectively. CONCLUSIONS: Nerve-sparing radical hysterectomy with pelvic lymph node dissection and pre- and postoperative irradiation remains the treatment of choice for most patients with early-stage and even Stage IIB cervical cancer. The radicalism and extent of lymph node dissection and parametrial resection should be individualized and tailored to tumor- and patient-related risk factors.

Correlation between first polar body morphology and further embryo development.

First polar body (PB) morphology of human oocytes can indicate further embryo development and viability. However, controversial data have been published in this topic. Our retrospective study analyses the fertilization and further development of oocytes in relation to different morphological features of the first PB. The morphology of 3387 MII oocytes from 522 in vitro fertilization (IVF) treatments were assessed before intracytoplasmic sperm injection (ICSI). Oocytes were classified according to their first PB morphology. Assessment of fertilization and embryonic development (cell number, embryo grade, amount of anuclear fragmentation and presence of multinucleated blastomeres) was performed 16-20 and 42-48 hours after ICSI. Our results show that fertilization rate and embryo quality is influenced by PB morphology, while speed of development is not affected by the morphology of the first PB. Contrary to previous findings, our results suggest that oocytes with a fragmented PB had a higher developmental ability than those with an intact PB. However, we observed a lower viability of oocytes with a large PB. Since there are contradictions in this and previous observations, an extensive study is needed with standard hormonal stimulation protocol and oocyte evaluation criteria.

Calcium sensitizers: What have we learned over the last 25 years?

The use of inotropes for correcting hemodynamic dysfunction in patients with congestive heart failure has been described over many decades. Drugs such as cardiac glycosides, cathecolamines, phosphodiestherase inhibitors, and calcium sensitizers have been in turn proposed. However, the number of new chemical entities in this therapeutic field has been surprisingly low, and the current selection of drugs is limited. One of the paradigm shifts in the discovery for new inotropes was to focus on 'calcium sensitizers' instead of 'calcium mobilizers'. This was designed to lead to the development of safer inotropes, devoid of the complications that arise due to increased intracellular calcium levels. However, only three such calcium sensitizers have been fully developed over the latest 30 years. Moreover, two of these, levosimendan and pimobendan, have multiple molecular targets and other pharmacologic effects in addition to inotropy, such as peripheral vasodilation. More recently, omecamtiv mecarbil was described, which is believed to have a pure inotropy action that is devoid of pleiotropic effects. When the clinical data of these three calcium sensitizers are compared, it appears that the less pure inotropes have the cutting edge over the purer inotrope, due to additional effects during the treatment of a complex syndrome such as acute congested heart failure. This review aims to answer the question whether calcium sensitization per se is a sufficient strategy for bringing required clinical benefits to patients with heart failure. This review is dedicated to the memory of Heimo Haikala, a true and passionate innovator in this challenging field.

Dose-dependent electrophysiological effects of the myosin activator omecamtiv mecarbil in canine ventricular cardiomyocytes.

Omecamtiv mecarbil (OM) is a myosin activator agent recently developed for treatment of heart failure. Although its action on extending systolic ejection time and increasing left ventricular ejection fraction is well documented, no data is available regarding its possible side-effects on cardiac ion channels. Therefore, the present study was designed to investigate the effects of OM on action potential morphology and the underlying ion currents in isolated canine ventricular myocytes using sharp microelectrodes, conventional patch clamp, and action potential voltage clamp techniques. OM displayed a concentration-dependent action on action potential configuration: 1 µM OM had no effect, while action potential duration and phase-1 repolarization were reduced and the plateau potential was depressed progressively at higher concentrations (10 - 100 µM; P < 0.05 compared to control). Accordingly, OM (10 µM) decreased the density of the transient outward K+ current (Ito), the L-type Ca2+ current (ICa) and the rapid delayed rectifier K+ current (IKr), but failed to modify the inward rectifier K+ current (IK1). It is concluded, that although the therapeutic concentrations of OM are not likely to influence cardiac ion currents significantly, alterations of the major cardiac ion currents can be anticipated at concentrations above those clinically tolerated.

Kinetic properties of intramembrane charge movement under depolarized conditions in frog skeletal muscle fibers.

Intramembrane charge movement was measured on skeletal muscle fibers of the frog in a single Vaseline-gap voltage clamp. Charge movements determined both under polarized conditions (holding potential, VH = -100 mV; Qmax = 30.4 +/- 4.7 nC/micro(F), V = -44.4 mV, k = 14.1 mV; charge 1) and in depolarized states (VH = 0 mV; Qmax = 50.0 +/- 6.7 nC/micro(F), V = -109.1 mV, k = 26.6 mV; charge 2) had properties as reported earlier. Linear capacitance (LC) of the polarized fibers was increased by 8.8 +/- 4.0% compared with that of the depolarized fibers. Using control pulses measured under depolarized conditions to calculate charge 1, a minor change in the voltage dependence (to V = -44.6 mV and k = 14.5 mV) and a small increase in the maximal charge (to Qmax = 31.4 +/- 5.5 nC/micro(F] were observed. While in most cases charge 1 transients seemed to decay with a single exponential time course, charge 2 currents showed a characteristic biexponential behavior at membrane potentials between -90 and -180 mV. The voltage dependence of the rate constant of the slower component was fitted with a simple constant field diffusion model (alpha m = 28.7 s-1, V = -124.0 mV, and k = 15.6 mV). The midpoint voltage (V) was similar to that obtained from the Q-V fit of charge 2, while the steepness factor (k) resembled that of charge 1. This slow component could also be isolated using a stepped OFF protocol; that is, by hyperpolarizing the membrane to -190 mV for 200 ms and then coming back to 0 mV in two steps. The faster component was identified as an ionic current insensitive to 20 mM Co2+ but blocked by large hyperpolarizing pulses. These findings are consistent with the model implying that charge 1 and the slower component of charge 2 interconvert when the holding potential is changed. They also explain the difference previously found when comparing the steepness factors of the voltage dependence of charge 1 and charge 2.

Extremely high maternal alkaline phosphatase serum concentration with syncytiotrophoblastic origin.

An extremely high alkaline phosphatase (AP) concentration (3609 IU/litre) was found in a 20 year old primigravida at 37 week's gestation, prompting an examination of its histological and cellular origin. Immunohistochemistry and western blots using antibodies against AP, Ki-67, phospho-protein kinase B (Akt), phospho-p44/42 mitogen activated protein kinase/extracellular signal regulated kinase 1/2 (MAPK/Erk1/2), phospho-glycogen synthase kinase-3beta (GSK-3beta), phospho-stress activated protein kinase/c-Jun N-terminal kinase, total-Akt, total-GSK-3beta, and phospho-p38-MAPK were carried out on index and control placental samples of the same gestational age. Compared with controls, staining of the index placenta showed minimal AP labelling of the brush border and remarkable positivity of the intervillous space. Cytotrophoblastic proliferation was 8-10% in the index placenta compared with 1-2% in controls. The index placenta also had raised concentrations of protein kinases with important roles in cell differentiation. The proliferation and differentiation rates of the cytotrophoblasts were found to be five times higher in index samples than in controls. It is hypothesised that loss of syncytial membranes in immature villi led to increased AP concentrations in the maternal circulation and decreased AP staining of the placenta. Loss of the syncytium might also stimulate increased proliferation of villous cytotrophoblasts, which would then fuse and maintain the syncytium.

Calpain-I induced alterations in the cytoskeletal structure and impaired mechanical properties of single myocytes of rat heart.

OBJECTIVE: The involvement of Calpain-I mediated proteolysis has been implicated in myofibrillar dysfunction of reperfused myocardium following ischemia (stunning). This study addresses the question whether ultrastructural alterations might be responsible for the depressed contractility. METHODS: Mechanical properties and protein composition of isolated myocytes after Calpain-I exposure (1.25 U/ml; 10 min; 15 degrees C; pCa 5.0) and of ischemic rat hearts following reperfusion were characterized. RESULTS: Maximal isometric force (44 +/- 5 kN/m2) at pCa 4.5 (pCa = -log[Ca2+]) decreased by 42.5% in Triton permeabilized myocytes (n = 11) after Calpain-I treatment. Force (and consequent myofilament disarrangement) during Calpain-I treatment was prevented by 40 mM BDM. The contractile force of Calpain-I exposed myocytes was significantly higher at submaximal levels of activation (pCa 5.5, 5.4 and 5.3) before maximal force development (pCa 4.5) than after maximal force development. The pCa50 value (5.40 +/- 0.02) determined from these initial test contractures did not differ significantly from that of untreated controls (5.44 +/- 0.03). However, after full activation Ca(2+)-sensitivity of force production in Calpain-I treated myocytes was significantly reduced (pCa50 5.34 +/- 0.02). This change in pCa50 was positively correlated with the reduction in maximal isometric force and was accompanied by sarcomere disorder. These findings imply that at least part of the Calpain-I induced mechanical alterations are dependent on force history. Measurements of the rate of force redevelopment after unloaded shortening suggested that Calpain-I did not affect cross-bridge kinetics. SDS gel electrophoresis and Western immunoblotting of Calpain-I treated myocytes revealed desmin degradation. The desmin content of postischemic myocardium was also reduced. CONCLUSION: Our results indicate that ultrastructural alterations may play an important role in the Calpain-I mediated cardiac dysfunction.