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Query: UNIPROT:P06889 (Mol)
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Ischemic contracture may be avoided by the provision of glucose under low flow conditions (Owen et al., 1990). However, accumulation of harmful metabolic end products may inhibit glycolytic flux and lessen the benefit of glucose. We assessed whether during increasingly severe flow restriction, provision of glucose might be harmful rather than beneficial, using the Langendorff perfused rat heart. Ischemic contracture (resting tension expressed as percent of preischemic developed pressure) was measured via a left ventricular balloon. Reductions in flow to 0, 0.015, 0.03, 0.06, 0.1, 0.2 or 0.4 ml/min/g wet wt over 60 min were tested. At zero flow, peak contracture was 61.4 +/- 3.5% (+/- S.E.) but fell to 15.6 +/- 6.3% with 0.4 ml/min/g wet wt (P < 0.05) in the presence of 11 mmol/l glucose. Time-to-onset of contracture was significantly delayed by the higher coronary flows. At coronary flows down to zero, the effect of glucose was inconstant or absent, but not harmful. With the residual flow at 0.2 ml/min/g wet wt, a dose response to glucose in ischemia was elicited, using concentrations of 0, 2.5, 5.5, 11 or 22 mmol/l. Maximum protection against ischemic contracture was found with 11 mmol/l glucose. However, once contracture occurred, functional recovery was severely impaired in all cases. Reducing glycogen prior to low flow ischemia (0.2 ml/min/g wet wt) with 11 mmol/l glucose increased peak contracture, and reduced the time-to-onset of contracture. Increased preischemic glycogen had little effect on contracture. Glycolytic flux fell in proportion to the coronary flow. However, there was an increased glucose extraction at lower flows of 0.1 and 0.2 ml/min/g wet wt, suggesting that it is the rate of delivery (i.e. coronary flow) which is the rate limiting step rather than enzyme inhibition by accumulated metabolites. If flow were further reduced, metabolite accumulation would become more important, such that with no flow, this would be the determinant of glycolytic flux rate. In our model, the two requirements for optimal protection from ischemia were (i) provision of glucose (11 mmol/l was optimal) and (ii) an adequate coronary flow to deliver the glucose and remove end product inhibition (greater than 0.06 ml/min/g wet wt).
J Mol Cell Cardiol 1995 Jan
PMID:Coronary flow and glucose delivery as determinants of contracture in the ischemic myocardium. 776 Mar 88

A potential detrimental role of endothelin-1 in myocardial ischemia/reperfusion injury was studied by use of the endothelin-1 antagonists BQ123 and BQ610. Isolated isovolumetric rat hearts were perfused at constant pressure. BQ123 (7 micrograms/min) and BQ610 (1.75 micrograms/min) did not alter mechanical function or coronary flow and shifted dose-response curves for endothelin-1 significantly to the right. In rats subjected to 30 min of no-flow ischemia, the increase of left ventricular resting pressure was significantly delayed by BQ123 and BQ610 compared to control (BQ123: 20 +/- 2* mmHg, BQ610: 19 +/- 2* mmHg, control: 44 +/- 4 mmHg at 15 min of ischemia, respectively, *P < 0.05 v control). With reperfusion after 30 min of ischemia, recovery of left ventricular developed pressure was not significantly affected but tended to be better with endothelin-1 antagonist pretreatment (BQ123: 20 +/- 3 mmHg; BQ610: 19 +/- 3 mmHg, control 12 +/- 3 mmHg). However, in hearts subjected to 15 min of ischemia followed by reperfusion, recovery of left ventricular developed pressure was improved by BQ610 pretreatment (BQ610: 52 +/- 8* mmHg, control: 24 +/- 6 mmHg). We conclude: BQ123 and BQ610 effectively antagonize the coronary constrictive effect of endothelin-1. BQ123 and BQ610 delay the development of contracture during ischemia and may improve functional recovery during reperfusion. Our findings suggest that endogenous endothelin-1 may contribute to ischemia/reperfusion injury.
J Mol Cell Cardiol 1995 Feb
PMID:Endothelin-1 contributes to ischemia/reperfusion injury in isolated rat heart-attenuation of ischemic injury by the endothelin-1 antagonists BQ123 and BQ610. 777 81

Heat shock has been shown to increase the cellular tolerances to ischemic injury. In this study, we examined the effects of heat shock induced by amphetamine on postischemic myocardial functional recovery in a setting of coronary revascularization for acute myocardial infarction. Intramuscular injection of amphetamine (3 mg/kg, i.m.) to pigs increased the body temperature to 42.5 degrees C within 1 h, and maintained this temperature for an additional 2 h. Fourty h after the amphetamine injection, the pigs were placed on by cardiopulmonary bypass and then isolated, in situ heart preparations were subjected to 1 h of global hypothermic cardioplegic arrest and 1 h of normothermic reperfusion. Postischemic myocardial performance was monitored by measuring left ventricular (LV) pressure, its dp/dt, myocardial segmental shortening (%SS), and coronary blood flow. Cellular injury was examined by measuring creatine kinase (CK) release. Biochemical measurements included quantification of plasma catecholamines and study of the induction of heat shock gene expression and antioxidative enzymes in the heart tissue. The results of this study indicated significantly greater recovery of LV contractile functions by amphetamine as demonstrated by improved recovery of LVDP (61% vs 52%), dp/dtmax (52% vs 44%), and segmental shortening (46.2% vs 10%). Myocardial CK release was significantly reduced in the amphetamine group. Furthermore, amphetamine pretreatment was associated with the induction of heat shock protein (HSP) 27 mRNA and stimulated Cu/Zn-superoxide dismutase and catalase levels, suggesting that amphetamine mediated improved postischemic ventricular recovery might be linked with its ability to induce heat shock and stimulate antioxidant enzymes.
Mol Cell Biochem 1994 Aug 17
PMID:Improved postischemic ventricular functional recovery by amphetamine is linked with its ability to induce heat shock. 784 74

Biodegradable controlled-release microsphere systems made with the biocompatible biodegradable polyester excipient poly(DL-lactide-co-glycolide) constitute an exciting new technology for drug delivery to the central nervous system (CNS). Implantable controlled-release microspheres containing dopamine (DA) or norepinephrine (NE) provide a novel means to compare DA- or NE -induced restitution of function in unilateral 6-hydroxydopamine lesioned rats. A suspension of 3 microL of DA- or NE-containing microspheres or empty microspheres was implanted in 2 sites of the DA denervated striatum of rats previously unilaterally lesioned with 6-hydroxydopamine. Contralateral-rotational behavior induced by apomorphine was used as an index of lesion success and, following implantation of the microspheres, also as an index of functional recovery. Interestingly, both DA- and NE-microsphere-implanted rats displayed a 30-50% reduction in the number of apomorphine-induced rotations up to 8 wk postimplantation. Rats implanted with empty microspheres did not demonstrate significant changes in contralateral rotational behavior. Behavioral studies following implantation of a mixture of DA and NE microspheres revealed an 80% decrease in the number of apomorphine induced rotations up to 4 wk. On conclusion of the studies, immunocytochemical examination revealed growth of DA and tyrosine hydroxylase immunoreactive fibers in the striatum of DA and NE microsphere-implanted rats. Functional behavior appeared to correlate with the degree of fiber growth. Preliminary electron microscopic studies showed signs of axonal sprouting in the vicinity of the implanted microspheres. No growth was noted in rats implanted with empty microspheres. This report reviews the abilities of both microencapsulated NE and DA to assure functional recovery and to promote DA fiber (re)growth in parkinsonian rats. This novel means to deliver these substances to the central nervous system could be of therapeutic usefulness in Parkinson's disease.
Mol Neurobiol
PMID:Catecholamine-containing biodegradable microsphere implants as a novel approach in the treatment of CNS neurodegenerative disease. A review of experimental studies in DA-lesioned rats. 788 96

Ischemic preconditioning in the rat significantly improves functional recovery following global ischemia by undefined mechanisms. It has been suggested that preconditioning protects by altering the tissue metabolic milieu during ischemia, either by increasing ischemic tissue accumulation of a beneficial substance (e.g. adenosine), or inhibiting tissue accumulation of a malefic component (e.g. protons). If this is the case, we hypothesized that no protection should be afforded by preconditioning against a prolonged period of hypoxia, since the continued coronary flow would prevent the accumulation of any metabolic products in the myocardium. To test this hypothesis, isolated buffer-perfused rat hearts were preconditioned by 5 min of ischemia + 5 min of reperfusion and then subjected to 30 min of ischemia, or 25 min of substrate-free hypoxia, or 60 or 90 min of hypoxia with substrate. Function was re-assessed after reperfusion/reoxygenation for a further 30 min and compared to non-preconditioned controls. Ischemic preconditioning improved functional recovery following 30 min of global ischemia (% recovery of developed pressure (LVDP) in control v preconditioned hearts was 31 +/- 4 v 66 +/- 6%; P < 0.05). Importantly, this protection was achieved almost entirely via a better preservation of diastolic function (end diastolic pressure = 78 +/- 3 mmHg in control and 40 +/- 5 mmHg in preconditioned hearts following 30 min of reperfusion; P < 0.05). However, no preconditioning-induced protection was observed following either substrate-free hypoxia or hypoxia with substrate (% recovery of LVDP in control v preconditioned hearts was 31 +/- 4 v 34 +/- 4% after 25 min of substrate-free hypoxia, 48 +/- 3 v 53 +/- 6% after 60 min of hypoxia + substrate and 25 +/- 5 v 30 +/- 6% after 90 min of hypoxia + substrate respectively). Furthermore, no protection by preconditioning against hypoxia-induced diastolic dysfunction was observed. We conclude that preconditioning protects against ischemic injury, but not hypoxic injury. Although hypoxia-induced injury may differ from that induced by ischemia, the results are consistent with the hypothesis that the continued presence of flow with hypoxia abolishes the protective effect of preconditioning. Furthermore, the results support the concept that preconditioning of the ischemic myocardium requires the accumulation of a factor in the ischemic myocardium, either to exert the preconditioning protective effect, or as a factor of injury against which preconditioning affords protection.
J Mol Cell Cardiol 1994 Nov
PMID:Can ischemic preconditioning protect against hypoxia-induced damage? Studies of contractile function in isolated perfused rat hearts. 789 71

Neurotrophic factors appear to be crucial for the survival and potential regeneration of injured neurons. Injury of the peripheral nervous system results in the induction of a number of neurotrophic molecules. Less is known about the response of central nervous tissue to injury. We have examined changes in levels of mRNA for three trophic factors, basic and acidic fibroblast growth factor (bFGF, aFGF), and nerve growth factor (NGF), after a standardized incomplete thoracic contusive spinal cord injury (SCI). RNase protection assays showed a rapid increase (3-fold) in the content of bFGF mRNA by 6 hours after SCI in tissue that included the injury site. No effect of injury was seen in segments of cervical or lumbar cord. bFGF mRNA at the injury site remained significantly increased at 1 and 7 days after SCI. Further, at 7 days, the increase was anatomically restricted to the rostral portion of the injury site suggesting the involvement of specific pathways in the maintenance of high levels of bFGF mRNA. No change in the levels of aFGF mRNA was seen after SCI. Similarly, no difference in the expression of the mRNA for NGF or its high affinity receptor (trkA), were observed at 6 h, 1 or 7 days following SCI. Our observation of a specific effect of SCI on bFGF mRNA expression supports a speculative hypothesis that bFGF may play a role in the partial recovery of function seen following incomplete contusive spinal cord injury.
Brain Res Mol Brain Res 1994 Mar
PMID:Increased basic fibroblast growth factor mRNA following contusive spinal cord injury. 801 71

The importance of the Na+/K+/Cl- co-transport system of the rat myocardial sarcolemma was studied under hypothermic ischemia by investigating the effect of the co-transport blockers furosemide and bumetanide on the sodium influx into the myocardium. The intracellular Na+ accumulation during hypothermic ischemia was followed by 23Na-NMR. For this purpose the shift reagent [Dy(TTHA)3-] (SR) was added to the Krebs-Henseleit (KH) perfusion solution. The same solution was also present during the hypothermic preservation. A significant reduction in the intracellular Na+ accumulation after 12 h was found when 100 microM furosemide was present during the perfusion and preservation periods. The intracellular Na+ levels returned to the pre-ischemic values after 1 h of reperfusion with KH in both the treated and control groups. Dose-response studies have indicated that 1-100 microM furosemide or 0.1 microM bumetanide added to the KH-SR solution reduced the Na+ influx significantly over 4 h of hypothermic ischemia. No statistically significant effect was found with furosemide concentration of 0.1 microM or with bumetanide concentrations higher or lower than 0.1 microM. 31P-NMR measurements showed no effect of the 100 microM furosemide on the intracellular ATP, the sum of inorganic phosphate and phosphomonoester, or pH levels over 4 h or after 12 h of hypothermic ischemia. Hearts treated with KH containing 100 microM furosemide showed, significantly higher functional recovery after 12 h of hypothermic ischemia than hearts treated only with KH. This study strongly indicates the existence of the Na+/K+/Cl- co-transport system in the intact rat heart sarcolemma, and its major role in sodium influx during hypothermic ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)
J Mol Cell Cardiol 1993 Dec
PMID:Inhibition of sodium influx and improved preservation of rat hearts during hypothermic ischemia by furosemide and bumetanide: a 23Na- and 31P-NMR study. 815 60

The cardioprotective effects of R56865 were studied in isolated rabbit hearts, blood-perfused with a support rabbit system. The effect on ischemic injury was evaluated by comparing myocardial contracture and contents of ATP catabolites and of lactate during 60 min of normothermic ischemia in untreated hearts (group I) and in hearts treated with 0.63 mg/kg of R56865 starting 20 min before ischemia (group II; n = 5 in each group). R56865 delayed the onset, and decreased the extent of ischemic contracture, but had no effect on the myocardial content of ATP, of its catabolites of lactate. The effect on reperfusion injury was studied by monitoring left ventricular function during 80-min reperfusion after the 60-min ischemia in three groups (n = 6 in each): an untreated group (group I) and two groups treated with R56865 given either before (group II) or after ischemia (group III). Ultrastructural changes and cellular calcium distribution after reperfusion were also studied. R56865 improved the recovery of function and prevented contracture during reperfusion. Left ventricular end-diastolic pressure was 13.2 +/- 2.8 mmHg in group II and 31.3 +/- 8.1 mmHg in group III vs 45.0 +/- 2.6 mmHg in group I (P < 0.0001 for II vs I; P > 0.05 for III vs I). Left ventricular developed pressure, maximum dP/dt and minimum dP/dt recovered to 71.0 +/- 5.4%, 98.9 +/- 6.1%, 85.3 +/- 4.8% of baseline values, respectively, in group II, to 64.5 +/- 3.0% (P > 0.05), 76.8 +/- 3.0%, 70.2 +/- 4.0% in group III, vs 52.0 +/- 6.5%, 58.9 +/- 6.9% and 53.6 +/- 5.8% in untreated hearts (P < 0.05 for II or III vs I). Coronary flow was 24.5 +/- 2.2 ml/min and 19.8 +/- 1.8 ml/min in groups II and III vs 14.8 +/- 0.7 ml/min (P < 0.05) in the untreated group. On histology the myocardium in hearts treated either before or after ischemia was well protected and calcium distribution was almost normal after reperfusion, while in untreated hearts, most of the myocardium displayed irreversible damage accompanied by massive intracellular calcium accumulation. We conclude that R56865 could attenuate Ca(2+)-overload, thereby reducing myocardial ischemia-reperfusion injury after an extended period of ischemia.
J Mol Cell Cardiol 1993 Dec
PMID:R56865, a Na(+)- and Ca(2+)-overload inhibitor, reduces myocardial ischemia-reperfusion injury in blood-perfused rabbit hearts. 815 64

Transforming growth factor alpha (TGF alpha) is a mitogenic polypeptide which acts at the epidermal growth factor receptor to produce its biologic effects. Recent studies have demonstrated that TGF alpha may act as a neurotrophic factor. Cerebral hemispherectomy (hemidecortication) is performed on some children with intractable epilepsy. Prior studies have demonstrated improved functional recovery in both children and animals when the surgery is performed at a very early age. In order to test whether TGF alpha may be involved in the functional recovery of the neostriatum following cerebral hemidecortication, we performed in situ hybridization for TGF alpha mRNA on brains of rats which underwent hemispherectomy at postnatal day (P) 6 or P12 or in adulthood, and sacrificed one, 7, or 30 days following surgery. Normal striatal expression in control animals was very high at P6 and then decreased throughout development. In animals undergoing lesion at earlier ages (P6 and P12), TGF alpha mRNA expression was first depressed in the ipsilateral neostriatum one day after surgery and then elevated to supranormal levels 7 and 30 days after surgery. Maximal decreases (40% below contralateral neostriatum) were seen in animals lesioned at P12 and sacrificed the next day. Maximal elevations (60% greater than opposite neostriatum) were seen in animals operated on at P6 and sacrificed 30 days post surgery. Expression in the adult animal was only mildly affected, with a 20% increase found in the ipsilateral caudate 7 days after the lesion, but no significant changes after one or 30 days survival.(ABSTRACT TRUNCATED AT 250 WORDS)
Brain Res Mol Brain Res 1994 Jan
PMID:Cerebral hemidecortication alters expression of transforming growth factor alpha mRNA in the neostriatum of developing rats. 816 11

It was recently reported that in rats exposure to heat shock leads to appearance of a myocardial heat shock protein (HSP 70) and to an increase in myocardial catalase activity. This correlated with an improvement in post-ischemic function either in Langendorff-perfused hearts after low-flow ischemia or in working hearts after short-term, no-flow ischemia. We investigated the effect of the same hyperthermic treatment on functional recovery from no-flow ischemia of various durations in isolated working rat hearts performing at high or low external workloads. Rats were heated to core temperature of 42 degrees C for 15 min. No significant protein oxidation (% oxidized methionine) was observed 2.5 hr after treatment. A protein with migration characteristics similar to HSP 70 was observed in hearts of heat shocked rats 24 hr after this treatment while their myocardial catalase activity was not increased. Hearts of similarly treated rats were excised 24 hr after hyperthermia and perfused in a working mode with Krebs-Henseleit buffer (1.25 mM Ca2+, 11 mM glucose). At 15 cm H2O preload and 100 cm H2O afterload after 30 min no-flow ischemia, control hearts recovered to 36.9%, 2%, 47.6%, and 21.5% of the preischemic values of heart rate-peak systolic pressure product (RPP), aortic output, coronary flow, and cardiac output, respectively. After only 25 min of ischemia the respective recovered values were 61.6%, 11.5%, 58.7%, and 33.5%. Throughout the recovery period these hemodynamic values were consistently higher in hearts of heat shocked animals than in those of control hearts but the differences were not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Biochem 1993 Dec 22
PMID:Role of catalase in myocardial protection against ischemia in heat shocked rats. 817 41


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