Proinflammatory cytokines depress cardiac efficiency by a nitric oxide-dependent mechanism

Proinflammatory cytokines (interleukin-1beta, tumor necrosis factor-alpha, and interferon-gamma; Cytomix) depress myocardial contractile work partially by stimulating expression of inducible nitric oxide (NO) synthase (iNOS). Because NO and peroxynitrite inhibit myocardial O2 consumption (MVO2), we examined whether this mechanism contributes to reduced cardiac work. In control isolated working rat hearts, cardiac work was stable for 60 min, followed by a decline from 60 to 120 min, without change in MVO2. Cardiac efficiency (work/MVO2) was therefore reduced from 60 to 120 min. Cytomix shortened the onset (within 20-40 min) and enhanced the depression in cardiac work and efficiency and inhibited MVO2 after 80 min. Mercaptoethylguanidine (MEG), an iNOS inhibitor and peroxynitrite scavenger, or the glucocorticoid dexamethasone (Dex) abolished the effects of Cytomix. iNOS expression was increased 10-fold by Cytomix and abolished by Dex but not MEG. That cytokine-induced depression in cardiac work precedes the reduction in MVO2 suggests, at least in the early response, that NO and/or peroxynitrite may not impair heart function by inhibiting mitochondrial respiration but reduce the heart's ability to utilize ATP for contractile work.

Functional outcome assessment of adults with right hemisphere brain damage

This article addresses functional outcome assessment of adults with cognitive-communicative disorders due to relatively focal right hemisphere brain damage (RBD). Our discussion observes the World Health Organization's orientation on the multidimensional consequences of health conditions. The WHO framework distinguishes specific deficits (impairments) from their functional consequences: disabilities, or restrictions in daily life activities and handicaps, or broader changes in life role participation. Although there is little evidence about the functional aftermath of RBD, especially in relation to cognitive-communicative disorders, we summarize the data and observations that are available and hypothesize about relationships among outcomes at different levels. We also describe some tools and procedures that may be useful for measuring functional outcomes after RBD, along with relevant caveats, and end with a discussion of research needs and future directions, emphasizing gaps that span the range from basic investigation to treatment research to instrument and procedure development.

Inorganic phosphate content and free energy change of ATP hydrolysis in regional short-term hibernating myocardium

OBJECTIVE

Short-term myocardial hibernation is characterized by an adaptation of contractile function to the reduced blood flow, the recovery of creatine phosphate content and lactate balance back towards normal, whereas ATP content remains reduced at a constant level. We examined the hypothesis that, despite the absence of ATP recovery, the short-term hibernating myocardium regains an energetic balance.

METHODS

An enzymatic method was modified for the measurement of inorganic phosphate (Pi) in transmural myocardial drill biopsies (about 5 mg). In 12 anaesthetized swine, moderate ischemia was induced by reduction of coronary inflow into the cannulated left anterior descending coronary artery to decrease regional myocardial function (sonomicrometry) by 50%.

RESULTS

The development of short-term hibernation was verified by the recovery of creatine phosphate content, the persistence of inotropic reserve in response to dobutamine and the absence of necrosis (triphenyl tetrazolium chloride). At 5-min ischemia, Pi was increased from 3.6 +/- 0.3 (SD) to 8.1 +/- 1.1 mumol/gwet wt (p < 0.05). The free energy of ATP hydrolysis (delta GATP) was decreased from -57.8 +/- 0.8 to -52.2 +/- 1.4 kJ/mol (p < 0.05). The relationships between function and Pi (r = -0.81) and delta GATP (r = -0.83), respectively, during control and at 5-min ischemia became invalid at 90-min ischemia, as myocardial blood flow and function remained reduced at a constant level, but Pi decreased back to 4.9 +/- 0.9 mumol/g (p < 0.05 vs. control and 5-min ischemia), and delta GATP fully recovered back to -57.2 +/- 1.3 kJ/mol (p < 0.05 vs. 5-min ischemia).

CONCLUSIONS

In short-term hibernating myocardium, myocardial inorganic phosphate content recovers partially and the free energy change of ATP hydrolysis returns to control values. Contractile function remains reduced by mechanisms other than an energetic deficit.

D alpha3, a new functional alpha subunit of nicotinic acetylcholine receptors from Drosophila

Nicotinic acetylcholine (ACh) receptors (nAChRs) are important excitatory neurotransmitter receptors in the insect CNS. We have isolated and characterized the gene and the cDNA of a new nAChR subunit from Drosophila. The predicted mature nAChR protein consists of 773 amino acid residues and has the structural features of an ACh-binding alpha subunit. It was therefore named D alpha3, for Drosophila alpha-subunit 3. The d alpha3 gene maps to the X chromosome at position 7E. The properties of the D alpha3 protein were assessed by expression in Xenopus oocytes. D alpha3 did not form functional receptors on its own or in combination with any Drosophila beta-type nAChR subunit. Nondesensitizing ACh-evoked inward currents were observed when D alpha3 was coexpressed with the chick beta2 subunit. Half-maximal responses were at approximately 0.15 microM ACh with a Hill coefficient of approximately 1.5. The snake venom component alpha-bungarotoxin (100 nM) efficiently but reversibly blocked D alpha3/beta2 receptors, suggesting that D alpha3 may be a component of one of the previously described two classes of toxin binding sites in the Drosophila CNS.

Adenylyl cyclase supersensitivity in opioid-withdrawn NG108-15 hybrid cells requires Gs but is not mediated by the Gsalpha subunit

On the cellular level, opioid dependence is characterized by a significant elevation of adenylyl cyclase (AC) activity after drug withdrawal, a regulatory phenomenon termed "AC supersensitivity" or "cAMP overshoot." The present study examines the role of the stimulatory G protein (Gs) in the expression of naloxone precipitated opioid withdrawal in chronically morphine (10 microM; 3 days) treated neuroblastoma X glioma (NG108-15) hybrid cells. Determination of high-affinity [3H]forskolin binding to intact cells, which provides a direct parameter for the binding of the activated alpha-subunit of Gs (Gsalpha) to AC, revealed that the enhancement of AC activity after opioid withdrawal is not caused by an increased stimulation of effector activity by Gsalpha. Although not a direct function of Gs, the expression of AC supersensitivity required Gsalpha-mediated stimulation of AC, because 1) the enhancement of AC activity after opioid withdrawal was observed only in the presence of low, but not of high concentrations of forskolin, and 2) chemical inactivation of Gsalpha by low pH pretreatment abolished the induction of AC supersensitivity. Moreover, the regulatory mechanism underlying AC supersensitivity not only required the presence of activated Gsalpha per se, but functional intact stimulatory signal transduction pathways. Indeed, blockade of prostaglandin E1 receptor/Gs interaction in situ with a site-specific anti-Gsalpha antibody, as well as uncoupling of prostaglandin E1 receptor signaling by cholera toxin-catalyzed ADP-ribosylation of Gsalpha, prevented the expression of AC supersensitivity in membranes from opioid-withdrawn cells. These results suggest that the enhancement of AC activity in opioid-dependent cells, triggered by drug withdrawal, is not a direct Gsalpha effect, but involves a secondary regulatory event that requires costimulation of AC by acutely receptor-activated Gsalpha.

Beta-blocker therapy of severe congestive heart failure in infants with left to right shunts

We report on the clinical and neurohumoral effects of adding low-dose propranolol to conventional therapy with digoxin and diuretics in 6 infants with severe congestive heart failure due to large left-to-right shunts. A significant decrease in heart failure scores and a decrease of the highly activated renin-angiotensin-1 aldosterone system by approximately 70% strongly suggests a beneficial effect of this new therapeutic approach.

A qualitative field method for monitoring pesticides in the edge-of-field runoff

A field method is described, which allows the qualitative estimation of pesticide contamination in the edge-of-field runoff. The method employs cheap and easy-to-use runoff sampling bottles, which were installed in an agricultural stream catchment over a period of three growing seasons. During this time 18 runoff events were detected, in nine of which insecticide contamination was measured (maximum concentrations: lindane 0.7 microgram l-1 and 12.7 micrograms kg-1, parathion 20 micrograms l-1 and 728 micrograms kg-1, fenvalerate 18.4 micrograms l-1 and 924 micrograms kg-1). These insecticides were detected mainly as particle-bound chemicals. On about 80% of the occasions the presence or absence of runoff measured in the field was in agreement with a simulation of runoff presence or absence using the runoff model KINEROS.

K(ATP)-channel activation: effects on myocardial recovery from ischaemia and role in the cardioprotective response to adenosine A1-receptor stimulation

1. Optimization of myocardial energy substrate metabolism improves the recovery of mechanical function of the post-ischaemic heart. This study investigated the role of K(ATP)-channels in the regulation of the metabolic and mechanical function of the aerobic and post-ischaemic heart by measuring the effects of the selective K(ATP)-channel activator, cromakalim, and the effects of the K(ATP)-channel antagonist, glibenclamide, in rat fatty acid perfused, working hearts in vitro. The role of K(ATP) channels in the cardioprotective actions of the adenosine A1-receptor agonist, N6-cyclohexyladenosine (CHA) was also investigated. 2. Myocardial glucose metabolism, mechanical function and efficiency were measured simultaneously in hearts perfused with modified Krebs-Henseleit solution containing 2.5 mM Ca2+, 11 mM glucose, 1.2 mM palmitate and 100 mu l(-1) insulin, and paced at 300 beats min(-1). Rates of glycolysis and glucose oxidation were measured from the quantitative production of 3H20 and 14CO2, respectively, from [5-3H/ U-14C]-glucose. 3. In hearts perfused under aerobic conditions, cromakalim (10 microM), CHA (0.5 microM) or glibenclamide (30 microM) had no effect on mechanical function. Cromakalim did not affect glycolysis or glucose oxidation, whereas glibenclamide significantly increased rates of glycolysis and proton production. CHA significantly reduced rates of glycolysis and proton production but had no effect on glucose oxidation. Glibenclamide did not alter CHA-induced inhibition of glycolysis and proton production. 4. In hearts reperfused for 30 min following 30 min of ischaemia, left ventricular minute work (LV work) recovered to 24% of aerobic baseline values. Cromakalim (10 microM), administered 5 min before ischaemia, had no significant effect on mechanical recovery or glucose metabolism. CHA (0.5 microM) significantly increased the recovery of LV work to 67% of aerobic baseline values and also significantly inhibited rates of glycolysis and proton production. Glibenclamide (30 microM) significantly depressed the recovery of mechanical function to < 1% of aerobic baseline values and stimulated glycolysis and proton production. 5. Despite the deleterious actions of glibenclamide per se in post-ischaemic hearts, the beneficial effects of CHA (0.5 microM) on the recovery of mechanical function and proton production were not affected by glibenclamide. 6. The data indicate that the cardioprotective mechanism of adenosine A1-receptor stimulation does not involve the activation of K(ATP)-channels. Furthermore, in rat fatty acid perfused, working hearts, stimulation of K(ATP)-channels is not cardioprotective and has no significant effects on myocardial glucose metabolism.

Research on physiological and physical concomitants of caregiving: where do we go from here?

This article discusses the current state of research on the physiological and physical concomitants of caregiving. We offer recommendations about theoretical, empirical, and treatment issues that researchers should consider in future investigations. Important theoretical issues include specifying acute and chronic stress in caregiving research. Empirical issues include sample selection, home versus clinic assessments, the use of experimental probes, moderating and mediating variables, and measurement issues (problems with self-report of health, medical records, physical exams, and lab assessments). Finally, we note that investigators should use this newfound knowledge to target interventions to specific subsets of vulnerable caregivers. In this way, basic research into caregiving, as a model of chronic human stress, can provide more focused approaches to benefit both caregivers and patients.

Health effects of caregiving: the caregiver health effects study: an ancillary study of the Cardiovascular Health Study

We propose that two related sources of variability in studies of caregiving health effects contribute to an inconsistent pattern of findings: the sampling strategy used and the definition of what constitutes caregiving. Samples are often recruited through self-referral and are typically comprised of caregivers experiencing considerable distress. In this study, we examine the health effects of caregiving in large population-based samples of spousal caregivers and controls using a wide array of objective and self-report physical and mental health outcome measures. By applying different definitions of caregiving, we show that the magnitude of health effects attributable to caregiving can vary substantially, with the largest negative health effects observed among caregivers who characterize themselves as being strained. From an epidemiological perspective, our data show that approximately 80% of persons living with a spouse with a disability provide care to their spouse, but only half of care providers report mental or physical strain associated with caregiving.

Activity restriction and prior relationship history as contributors to mental health outcomes among middle-aged and older spousal caregivers

In a sample of cancer patients (n = 75) and spousal caregivers (24 men and 51 women), restriction in caregiver routine activities mediated associations between caregiving stress (patient symptom severity) and caregiver depressed affect and resentment. Moreover, the antecedents and affective consequences of caregiver activity restriction were consistent with the theory of communal relationships (e.g., M. S. Clark & J. Mills, 1979, 1993). If a relationship had been communal in the past (i.e., characterized by mutual concern for and responsiveness to one another's needs), activity restriction was predicted by intimacy and affectional loss (rather than by the severity of patient symptoms) and in turn predicted caregiver depressed affect. Among caregivers in less communal relationships, activity restriction was predicted by severity of patient symptoms (rather than by intimacy and affectional loss) and in turn predicted resentment of care recipients and the caregiving role.

Caregiving from the recipient's perspective: negative reactions to being helped

This study investigated predictors of negative reactions to assistance provided to a physically disabled spouse (n = 276, M age: 76.6 years) and the consequences that negative reactions may have for the mental health of the care recipient. Nearly 40% of recipients reported some emotional distress in response to help they received. Fatalistic attitudes, perceived control, and lower self-esteem predicted greater helping distress, whereas lower self-esteem, fatalistic beliefs, and marital conflict were especially likely to lead to helping distress for those who received higher levels of assistance. Helping distress was also found to predict depression as much as 1 year later, suggesting that there may be long-term consequences of negative reactions to assistance. These findings have important implications for the study of caregiving and the relationship between physical impairment and depression.

Intrinsic ANG II type 1 receptor stimulation contributes to recovery of postischemic mechanical function

To determine whether intrinsic angiotensin II (ANG II) type 1 receptor (AT1-R) stimulation modulates recovery of postischemic mechanical function, we studied the effects of selective AT1-R blockade with losartan on proton production from glucose metabolism and recovery of function in isolated working rat hearts perfused with Krebs-Henseleit buffer containing palmitate, glucose, and insulin. Aerobic perfusion (50 min) was followed by global, no-flow ischemia (30 min) and reperfusion (30 min) in the presence (n = 10) or absence (n = 14) of losartan (1 mumol/l) or the cardioprotective adenosine A1 receptor agonist N6-cyclohexyladenosine (CHA, 0.5 mumol/l, n = 11). During reperfusion in untreated hearts (controls), left ventricular (LV) minute work partially recovered to 38% of aerobic baseline, whereas proton production increased to 155%. Compared with controls, CHA improved recovery of LV work to 79% and reduced proton production to 44%. Losartan depressed recovery of LV work to 0% without altering proton production. However, exogenous ANG II (1-100 nmol/l) in combination with losartan restored recovery of LV work during reperfusion in a concentration-dependent manner, suggesting that postischemic recovery of function depends on intrinsic AT1-R stimulation.

The role of neuroticism and mastery in spouse caregivers' assessment of and response to a contextual stressor

Data from more than 300 spousal caregivers and their care recipients were analyzed to demonstrate the effects of caregivers' personality attributes--neuroticism and mastery--on their assessment of a contextual stressor (the care recipient's behavioral and functional impairment) and on their experience of distress associated with that stressor. Caregivers who were high in neuroticism and/or low in mastery reported higher levels of behavioral and functional impairment in their disabled spouse and experienced more strain and depressive symptoms associated with caregiving relative to caregivers with lower neuroticism or higher mastery scores. We further showed that the widely reported association between caregiver-assessed impairment of the care recipient and caregiver outcomes can in part be explained by caregivers' personality attributes, such as neuroticism and mastery. Our findings that caregivers' personality variables are related to their assessment of a given objective stressor and their response to a given level of stress have implications for interventions targeting caregivers and for the use of caregivers as proxy informants.

Translocation of phosducin in living neuroblastoma x glioma hybrid cells (NG 108-15) monitored by red-shifted green fluorescent protein

Activation of G protein-coupled receptors triggers translocation of certain proteins from cytoplasm to cell membrane located targets. One of these cytosolic proteins is phosducin (Phd) which has been described to compete with G protein-coupled receptor kinases for Gbetagamma dimers attached to the cell membrane, thereby attenuating desensitization of activated receptors. These features of protein redistribution prompted us to examine whether stimulation of membrane associated E-prostaglandin receptors coupled to Gs causes Phd to migrate towards the plasma membrane. We made use of enhanced green fluorescence protein (EGFP), a reporter protein, to follow redistribution of Phd both by means of confocal microscopy and biochemical techniques in living neuronal NG 108-15 hybrid cells challenged with prostaglandin E1 (PGE1). The cells were transiently transfected to express Phd fused to the C-terminus of EGFP, or to express EGFP only. Overexpression of the proteins is implied by FACS analysis as well as by western blot technique, and the functional integrity of EGFP-tagged Phd was confirmed by its ability to elevate cAMP accumulation. Time-lapse imaging of single living cells by means of confocal microscopy revealed that exposure to prostaglandin causes EGFP/Phd, which is evenly spread throughout the cell, to relocate towards the membrane within few minutes. Fluorescence associated with the cell nucleus displayed little rearrangement. The principle finding that prostaglandin triggers translocation of Phd from cytosol to the cell periphery was verified with membranes prepared from EGFP/Phd expressing cells. We found maximal concentrations of membrane associated fluorescent material 5 to 7 min upon prostaglandin exposure. The present study reports for living NG 108-15 hybrid cells that PGE1 stimulation causes cytosolic Phd to translocate towards the membrane, where it is believed to bind to G protein subunits such as Gbetagamma and Galphas.

Correlates and prevalence of benzodiazepine use in community-dwelling elderly

OBJECTIVE

To describe the prevalence of benzodiazepine use, sociodemographic and physical health factors associated with use, dosages taken, and directions for use among individuals aged 65 years and older.

DESIGN

Cross-sectional analysis of baseline data from the community-based, prospective observational Cardiovascular Health Study.

PATIENTS/PARTICIPANTS

Medicare eligibility lists from four U.S. communities were used to recruit a representative sample of 5,201 community-dwelling elderly, of which 5,181 participants met all study criteria.

MEASUREMENTS AND MAIN RESULTS

Among participants, 511 (9.9%) were taking at least one benzodiazepine, primarily anxiolytics (73%). Benzodiazepines were often prescribed to be taken pro re nata (PRN "as needed"), and 36.5% of prescriptions with instructions to be taken regularly were taken at a dose lower than prescribed. Reported over-the-counter (OTC) sleep aid medication use was 39.2% in benzodiazepine users and 3.3% in nonusers. In a multivariate logistic model, the significant independent correlates of benzodiazepine use were being white (odds ratio [OR] 1.9; 95% confidence interval [CI] 1.0, 3.4), female (OR 1.7; CI 1.4, 2.2), and living in Forsyth County, North Carolina, or Washington County, Maryland, compared with living in Sacramento County, California, or Allegheny County, Pennsylvania (OR 2.3; CI 1.4, 2.2); having coronary heart disease (OR 1.6; CI 1.2, 2.1), health status reported as poor or fair (OR 1.8; CI 1.4, 2.3), self-reported diagnosis of nervous or emotional disorder (OR 6.7; CI 5.1, 8.7), and reporting use of an OTC sleep aid medication (OR 18.7; CI 14.1, 24.7).

CONCLUSIONS

One in 10 participants reported taking a benzodiazepine, most frequently an anxiolytic, often at a lower dose than prescribed and usually PRN. The high prevalence of OTC sleep aid medication and benzodiazepine use may place the patient at increased risk of psychomotor impairment. Physicians should assess OTC sleep aid medication use when prescribing benzodiazepines.

Positron emission tomography analysis of [1-(11)C] acetate kinetics in short-term hibernating myocardium

BACKGROUND

Modeling of the time-[1-(11)C]acetate activity curve assumes a constant concentration of labeled tricarboxylic acid cycle intermediates and associated metabolites, such as glutamate and aspartate, which may, however, decrease in short-term hibernating myocardium.

METHODS AND RESULTS

In 12 anesthetized pigs, [1-(11)C]acetate was injected as a bolus into the cannulated left anterior descending coronary artery during normoperfusion, inotropic stimulation, and early (5 to 45 minutes) and prolonged ischemia (60 to 90 minutes). Regional myocardial oxygen consumption (MVO2, microliters per minute per gram) was measured, and the absence of necrosis was verified by triphenyl tetrazolium chloride staining. Inotropic stimulation increased MVO2 from 52.5+/-7.4 to 195.4+/-36.2 (mean+/-SD) and the rate constant (kmono, minutes[-1]) of [1-(11)C]acetate clearance from 0.094+/-0.018 to 0.322+/-0.076. During early ischemia, MVO2 and kmono were decreased to 24.3+/-8.5 and 0.061+/-0.011, respectively. Kmono closely correlated to MVO2 during normoperfusion, inotropic stimulation, and early ischemia. In short-term hibernating myocardium, however, at an unchanged MVO2, kmono increased toward control values (0.080+/-0.014). Myocardial glutamate and aspartate concentrations (biopsies) decreased to 47+/-26% and 77+/-18%; the peak count rate decreased to 66+/-22% of its respective control value. After correction for the decreases in glutamate and aspartate or in peak count rate, kmono was again decreased (0.050+/-0.016 or 0.052+/-0.014, respectively), and a close relationship to MVO2 was restored.

CONCLUSIONS

Kmono correlates to MVO2 in short-term hibernating myocardium when the decreases in aspartate and glutamate or in peak count rate are considered.

Phosducin expression in NG 108-15 hybrid cells enhances prostaglandin E1 stimulated adenylate cyclase activity

Phosducin (Phd), a cytosolic protein, has been proposed to compete with certain receptor kinases for Gbetagamma of heterotrimeric G proteins, and may inhibit GTPase activity of G alpha s. These suggestions together with the enhancing effect of Phd on odorant-induced cAMP accumulation let us assume a stimulatory action of the protein on intracellular signaling. Therefore, this investigation was designed to examine the excitatory effect of PGE1 on signal transmission in neuroblastoma x glioma hybrid cells (NG 108-15) overexpressing Phd. The neuronal cells stably expressing Phd were found to display a 3 to 4-fold increased sensitivity to PGE1 as compared to wild type cells, using cAMP accumulation as measure. Examination of membranes prepared from Phd-overexpressing cells revealed an elevated GTPase activity as indicated by the formation of 32Pi upon PGE1 challenge. This activity was inhibited by exogenous Phd. In addition, receptor independent stimulation of adenylate cyclase by forskolin reveals an increased formation of cAMP in Phd expressing cells, which is accompanied by an increased binding of [3H]forskolin. The findings let us propose that Phd elevates intracellular levels of functional G alpha s which accounts for the increased response to PGE1.

Activity restriction and prior relationship history as contributors to mental health outcomes among middle-aged and older spousal caregivers

In a sample of cancer patients (n = 75) and spousal caregivers (24 men and 51 women), restriction in caregiver routine activities mediated associations between caregiving stress (patient symptom severity) and caregiver depressed affect and resentment. Moreover, the antecedents and affective consequences of caregiver activity restriction were consistent with the theory of communal relationships (e.g., M. S. Clark & J. Mills, 1979, 1993). If a relationship had been communal in the past (i.e., characterized by mutual concern for and responsiveness to one another's needs), activity restriction was predicted by intimacy and affectional loss (rather than by the severity of patient symptoms) and in turn predicted caregiver depressed affect. Among caregivers in less communal relationships, activity restriction was predicted by severity of patient symptoms (rather than by intimacy and affectional loss) and in turn predicted resentment of care recipients and the caregiving role.

Caregiving from the recipient's perspective: negative reactions to being helped

This study investigated predictors of negative reactions to assistance provided to a physically disabled spouse (n = 276, M age: 76.6 years) and the consequences that negative reactions may have for the mental health of the care recipient. Nearly 40% of recipients reported some emotional distress in response to help they received. Fatalistic attitudes, perceived control, and lower self-esteem predicted greater helping distress, whereas lower self-esteem, fatalistic beliefs, and marital conflict were especially likely to lead to helping distress for those who received higher levels of assistance. Helping distress was also found to predict depression as much as 1 year later, suggesting that there may be long-term consequences of negative reactions to assistance. These findings have important implications for the study of caregiving and the relationship between physical impairment and depression.

Expression of calcium regulatory proteins in short-term hibernation and stunning in the in situ porcine heart

BACKGROUND

Myocardial hibernation and stunning are characterised by a reversible contractile dysfunction during and after ischaemia, respectively. Calcium homeostasis might be disturbed in hibernation and stunning due to altered expression of cardiac proteins involved in calcium handling.

METHODS

In enflurane-anaesthetised swine the coronary blood flow through the left anterior descending coronary artery was decreased to reduce regional contractile function (microsonometry) by approximately 50%. In transmural biopsies obtained during ischaemia and reperfusion creatine phosphate as well as the expression of sarcoplasmic reticulum calcium ATPase (SERCA), phospholamban (PLB), calsequestrin (CSQ), and troponin inhibitor (TnI) were determined.

RESULTS

During ischaemia creatine phosphate, after an initial reduction, recovered back to control values, and necrosis was absent (hibernation). After 90 min of ischaemia the myocardium was reperfused for 120 min but regional contractile function continued to be depressed (stunning). PLB, SERCA, CSQ, and TnI proteins were unchanged during ischaemia as well as reperfusion. Likewise, levels of PLB and SERCA mRNAs were unchanged.

CONCLUSION

It is concluded that other mechanisms than altered expression of these regulating proteins underlie the contractile dysfunction observed during acute ischaemia, short-term hibernation and stunning.