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Min Occlusion (min + occlusion)

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Medical Sciences	100%

Selected Abstracts

Effect of dantrolene in an in vivo and in vitro model of myocardial reperfusion injury

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 2 2000
B. Preckel
Background: In skeletal muscle, dantrolene reduces free cytosolic calcium by inhibiting calcium release from the sarcoplasmic reticulum. A similar effect in ischemic-reperfused heart cells would protect myocardial tissue against reperfusion injury. We tested the hypothesis that dantrolene infusion during reperfusion protects the heart against reperfusion injury. Methods: Isovolumetric beating rat hearts were subjected to 30 min of ischemia followed by 60 min of reperfusion. Left ventricular (LV) developed pressure (LVDP) and creatine kinase release (CKR) were determined as indices of myocardial performance and cellular injury, respectively. In the treatment groups, dantrolene (25 (DAN25) or 100 (DAN100) ,mol l,1) was infused during the first 15 min of reperfusion; control hearts received the respective concentration of the vehicle (mannitol (CON25, CON100), each group n=7). To investigate the effects of dantrolene on reperfusion injury in vivo, 18 chloralose-anesthetized rabbits were subjected to 30 min occlusion and 180 min reperfusion of a major coronary artery. LV pressure (LVP), cardiac output (CO), and infarct size were determined. During the last 5 min of ischemia, nine rabbits received 10 mg kg,1 dantrolene intravenously (DAN). Another nine rabbits received the vehicle (dimethylsulfoxide) and served as controls (CON). Results: In isolated rat hearts, there was no recovery of LVDP in any group. Total CKR during 1 h of reperfusion was 845±76 (CON100) and 550±81 U g,1 dry mass (DAN100, P<0.05). In rabbits in vivo, hemodynamic baseline values were similar between groups (CON vs. DAN: LVP, 99±6 (mean±SEM) vs. 91±6mm Hg, P=0.29; CO, 252±26 vs. 275±23 ml min,1, P=0.53). During coronary artery occlusion, LVP and CO were reduced in both groups (CON: LVP, 89±3%; CO, 90±5% of baseline values) and LVP did not recover to baseline values during reperfusion (51±5% (CON) vs. 67±7% (DAN) of baseline, P=0.10). Infarct size was 41±4% of the area at risk in controls and 37±6% in dantrolene treated hearts (P=0.59). Conclusions: Dantrolene reduced CKR, indicating an attenuation of lethal cellular reperfusion injury in isolated rat hearts. However, in the rabbit in vivo, there was no effect on the extent of reperfusion injury after regional myocardial ischemia. [source]

Siberian ginseng reduces infarct volume in transient focal cerebral ischaemia in Sprague-Dawley rats

PHYTOTHERAPY RESEARCH, Issue 2 2005
Yungmin Bu
Abstract Siberian ginseng, the root and stem bark of Acanthopanax senticosus Harms, has been used as a tonic and adaptogen to strengthen qi in traditional Korean medicine. The neuroprotective effects of water extracts of A. senticosus (ASW) were investigated in transient middle cerebral artery occlusion (MCAo, 90 min occlusion, 24 h reperfusion) of Sprague-Dawley rats. The infarct volume was significantly reduced by 36.6% after the peritoneal injection of ASW (100 mg[sol ]kg) compared with the control. In the immunohistochemical study, ASW markedly inhibited both cyclooxygenase-2 and OX-42 expressions in the penumbral region at 24 h after MCAo. These results suggest that A. senticosus has a neuroprotective effect by inhibiting inflammation and microglial activation in brain ischaemia. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Sildenafil (Viagra) reduces arrhythmia severity during ischaemia 24 h after oral administration in dogs

BRITISH JOURNAL OF PHARMACOLOGY, Issue 4 2004
Orsolya Nagy
Sildenafil (Viagra) prolongs repolarisation in cardiac muscle, an effect that could lead to ventricular fibrillation (VF). Sildenafil (2 mg kg,1) was given by mouth to 12 mongrel dogs and, 24 h later, these dogs were anaesthetised, thoracotomised and subjected to a 25 min occlusion of the anterior descending coronary artery. Haemodynamic parameters were similar in this and the control group, but there were fewer and less serious ventricular arrhythmias during occlusion in the sildenafil group (VF 17 vs 60%; ventricular premature beats 140±52 vs 437±127% and episodes of ventricular tachycardia 4.0±3.2 vs 19.3±7.7%, all P<0.05). However, reperfusion VF and indices of ischaemia severity (epicardial ST-segment mapping, inhomogeneity) were not modified by the drug. Sildenafil increased the QT interval, especially during ischaemia. Our conclusion is that ischaemia-induced ventricular arrhythmias are reduced by sildenafil, but this protection is less pronounced than that following cardiac pacing or exercise. British Journal of Pharmacology (2004) 141, 549,551. doi:10.1038/sj.bjp.0705658 [source]

Hypervolaemia improves global and local function and efficiency in postischaemic myocardium

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 8 2001
FY Du
SUMMARY 1. In the present study, we investigated the effects of blood volume on postischaemic function and efficiency. In 14 anaesthetized dogs, following recovery from a period of 15 min occlusion of the left anterior descending coronary artery, the effects of hypervolaemia (HYPER; 15% increased volume produced by fast infusion of Hespan; B Braun Medical, Irvine, CA, USA), normovolaemia (NORMO) and hypovolaemia (HYPO) were studied. 2. Although myocardial O2 consumption was not significantly increased by volume (6.37±0.94 vs 6.89±1.1 mL/min per 100 g for HYPO and HYPER, respectively), local work of the stunned myocardium was markedly elevated (8.8±1.7 vs 22.5±3.5 g·mm/ beat, for HYPO and HYPER, respectively; P < 0.05). External work of the heart was also significantly improved (71.8±12.7 vs 139.5±16.2 mmHg·L/min for HYPO and HYPER, respectively). These data indicate markedly improved efficiency produced by volume, because work was increased with no change in myocardial O2 consumption. 3. Local dysfunction was characterized by several parameters, including systolic bulge, end-diastolic length, delay to onset of shortening, end shortening time delay (EST) and tail work ratio. Hypervolaemia reduced EST compared with hypovolaemia (98.6±18.3 vs 110.7±14.9 msec, respectively; P < 0.05) and improved tail work ratio (28.0±7.0 vs 36.0±7.0%, respectively; P < 0.05), with no effects on systolic bulge, end-diastolic length and delay to onset of shortening. 4. Thus, even in the postischaemic myocardium, increasing work by volume is energetically efficient and is accompanied by partial improvement of local dysfunction. [source]