Tissue oxygen pressure was measured in the pig heart during repeated coronary artery occlusions. ptO2 was measured with an array-multiwire-electrode across the border zone, i.e. the transition zone between normal and ischaemic myocardium. The LAD was occluded three times, each lasting 5 min and with 55 min of reperfusion between the occlusions. Three groups of animals were studied: Group 1 served as controls; Group 2 were given metoprolol 0.3 mg/kg i.v. after the first LAD occlusion; Group 3 were given isoprenaline in a continuous infusion, started after the first LAD occlusion and continued throughout the rest of the experiment. Heart rate differed as expected between the two treated groups. The pattern of ptO2 values across the border zone repeated itself for each animal. No change in the pattern of ptO2 values was seen in either treatment group. In conclusion, there were no indications that it was possible to change the ptO2 of the border zone in the pig heart either with metoprolol or isoprenaline in the doses used.

Animals↗

PubMedDate not supplied

Exogenous adenosine induces flowmotion in skeletal muscle microcirculation of the anesthetized rat.

The aim of this study was to investigate the characteristics of the microcirculatory blood flow with laser-Doppler flowmetry (LDF) in skeletal muscle during both regional and systemic infusions of adenosine. A laser-Doppler flowmeter probe was placed on the left gastrocnemius muscle in anesthetized rats. Adenosine was given either systemically in the jugular vein (group A) or administered regionally in the iliac artery (group B). The infusion of adenosine was increased stepwise by 50 micrograms/kg/min, every 10 min, up to 400 micrograms/kg/min. In group A there was a dose-dependent decrease in mean arterial pressure as well as in LDF flow; flowmotion of the LDF signal with a frequency of 1.6 cycles/min was seen at a mean adenosine dose of 240 micrograms/kg/min at a blood pressure of 60 mm Hg. In group B there was a dose-dependent decrease of mean arterial blood pressure but not as marked compared to group A, meanwhile the LDF flow was unchanged; flowmotion was seen at a mean adenosine dose of 220 microgram/kg/min at a blood pressure of 72 mm Hg, with a frequency of 1.5 cycles/min. This study demonstrates that adenosine, given either regionally intraarterially with maintained blood flow, or intravenously with reduced blood flow, induces flowmotion in skeletal muscle microcirculation with a frequency of approximately 1.5 cycles/min.

Adenosine↗

PubMedDate not supplied

Influence of pentobarbital, propofol and ketamine on skeletal muscle capillary perfusion during hemorrhage: a comparative study in the rabbit.

Anesthetics affect tissue blood flow, which is of importance especially in situations of inadequate perfusion, as in hemorrhage. The present study compared the effect of three commonly used anesthetic agents on skeletal muscle capillary and regional blood flow during and after recovery from hemorrhage. Three groups of rabbits were anesthetized randomly with either pentobarbital, propofol or ketamine, chosen such that the anesthetic level, blood pressure and withdrawn blood volume were comparable in all groups. Capillary blood flow was measured using a local hydrogen clearance technique with a multi-wire microelectrode, placed on the left vastus medialis muscle surface, and the contralateral site served for regional microcirculatory blood flow measurements using laser-Doppler flowmetry. Hemorrhage was induced by withdrawal of blood to a mean arterial pressure of 40 mm Hg and monitoring was continued during the subsequent spontaneous recovery period of 120 min. Both capillary and regional blood flow decreased significantly during hemorrhage in all groups. The flow values in the pentobarbital group were given a mean value of 100% and the other two groups were compared with this. Local hydrogen clearance flow decreased from a relative baseline level of 100 to 64% during hemorrhage with pentobarbital, from 87 to 43% with propofol and from 146 to 70% with ketamine. Laser-Doppler flowmetry flow decreased from relative baseline levels of 100, 96 and 139%, to 71, 77 and 103%, respectively, during hemorrhage, whereas the percentage of zero capillary flow values increased from 4 to 34, 19 to 50 and 5 to 27% in the three groups, respectively. The results of the present study indicate that capillary perfusion is best maintained in the ketamine group followed by pentobarbital and propofol last. Furthermore, the flow distribution shapes for each anesthetic indicate a more pronounced deregulation of capillary blood flow in the propofol group than in the others, even at baseline.

Anesthetics↗

PubMedDate not supplied

Effect of buflomedil on cell metabolism in ischemic muscle.

The effect of Buflomedil on cell metabolism in ischemic muscle was studied in pigs. Six pigs received Buflomedil 6 mg per kg intravenously 30 minutes prior to induction of total leg ischemia, whereas 6 control animals were not premedicated. Arterial and venous blood samples and muscle specimens from the ischemic leg were collected prior to ischemia, after 5 hours of ischemia, and after 10 minutes and 30 minutes of reperfusion of the leg, and analysed for metabolic parameters. Similar decreases in local venous pH and PO2 indicated comparable and severe leg ischemia in both groups. Similar increases in venous and arterial concentrations of potassium and creatine kinase indicated a comparable degree of cell damage in the two groups. The ischemic muscle specimens in the Buflomedil group contained significantly higher phosphocreatine (PC) levels (p less than 0.01) and significantly lower lactate levels (p less than 0.01) than did the control group, whereas ATP levels were comparable in the two groups. We conclude that Buflomedil reduces PC-conversion, glucolytic activity and energy demands of the ischemic cell.

Adenosine Triphosphate↗

PubMedDate not supplied