Termination Of Occlusion Research Articles

Effect of Water-Soluble Echinochrome Analog on Arrhythmia Severity in Experimental Model of Acute Myocardial Ischemia.

The effects of therapeutic or preventive-therapeutic administration of water-soluble echinochrome analog U-441 on arrhythmia severity assessed by a set of myocardial spatio-temporal depolarization and repolarization parameters were examined on the model of acute myocardial ischemia in cats. Coronary occlusion increased activation time and decreased repolarization time in the ischemic zone; in addition, it increased both global and borderline (local) dispersions of repolarization. The linear regression model showed that only activation time values measured at the initial state and at termination of occlusion were associated with total arrhythmia score during ischemia (regression coefficient β=0.338, 95%CI=0.074-0.602, p=0.015 and β=0.720, 95%CI=0.323-1.117, p=0.001, respectively). The study revealed no association between administration of echinochrome analog U-441 and arrhythmia severity.

Release of endogenous catecholamines in two different regions of the nucleus of the solitary tract as influenced by carotid occlusion

The effects of carotid occlusion on the release of catecholamines in the nucleus of the solitary tract (NTS) were investigated in anaesthetized cats. Two aspects of the nucleus (rostral or intermediate NTS) were superfused bilaterally through push-pull cannulae with artificial CSF and the release of the endogenous dopamine, noradrenaline and adrenaline was determined in the superfusate radioenzymatically. The superfusion rate was 150 microliters/min or 800 microliters/min. In some experiments, superfusion of the intermediate NTS was carried out after denervation of the aortic arch. In the rostral NTS superfused at a rate of 150 microliter/min, bilateral carotid occlusion led to a rise in blood pressure and decreased the release rate of dopamine. These changes continued after occlusion termination. The release rate of noradrenaline was transiently diminished during occlusion. The release of this amine was also decreased after occlusion termination. The release rate of adrenaline was not influenced during carotid occlusion, but it was found to be diminished after termination of the occlusion. Superfusion of the rostral NTS at a rate of 800 microliters/min also reduced the release rate of adrenaline after termination of carotid artery occlusion. In the intermediate NTS (superfusion rate 150 microliters/min) similar effects of the carotid occlusion on the release rates of dopamine and noradrenaline were observed. In this aspect of the NTS, denervation of the aortic arch abolished the decrease in the noradrenaline release during carotid occlusion, while the release rates of dopamine and adrenaline were decreased during and after termination of the carotid occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Breath hydrogen reflects canine intestinal ischemia.

The relationship between breath hydrogen excretion and intestinal ischemia was investigated in nine mechanically ventilated dogs under pentobarbital anesthesia. An ileal segment was isolated in situ, ligated at each end, and insufflated with hydrogen. Expired air was collected at intervals. Blood volume was reduced 30% by three successive equivalent hemorrhages 10 min apart. Local bowel ischemia was produced by clamping the blood supply to the isolated segment for 10 min. Graded hemorrhage produced step-wise reductions in breath hydrogen concentration, to 77 +/- 13, 66 +/- 15, and 35 +/- 8% (mean +/- S.E.) of baseline after the first, second, and third hemorrhages, respectively. These reductions correlated highly (r = 0.84; P less than 0.01) with declines in mean aortic blood pressure. Occlusion of blood supply caused a significant (P less than 0.025) decrease in breath hydrogen concentration and excretion to 39 +/- 14% of baseline. Termination of occlusion was followed within 2 min by a 7-fold increase in breath H2 concentration above the original baseline, probably reflecting reactive hyperemia. Breath hydrogen measurements appear to reflect functional (hemorrhagic shock-induced) and mechanical (vascular occlusion induced) enteric ischemia in dogs.

Hemodynamic and metabolic concomitants of brain swelling and cerebral edema due to experimental cerebral infarction.

✓ Severe cerebral ischemia was produced in 25 baboons by clamping the carotid and vertebral arteries bilaterally for 10 minutes. Cerebral hemodynamics and metabolism were monitored throughout. Cerebral anoxia was less severe in animals in which a marked pressor response occurred due to ischemia of the vasomotor center, and a reversible type of brain swelling was usual. In those with more severe ischemic anoxia, progressive cerebral edema was a pathological entity. Evidence is presented that cerebral edema was caused by loss of autoregulation of cerebral blood flow (CBF) concomitant with hyperemia and an increase of water and chloride content of brain tissue. Cerebral edema began when CBF was reduced during occlusion and progressed for several hours after termination of occlusion. Evidence is adduced that uncoupling of oxidative phosphorylation may be an important concomitant of cerebral edema.

Electroencephalographic changes associated with experimental temporary focal cerebral anemia

1. 1. The right middle cerebral artery was occluded in 19 monkeys, in 9 animals permanently and in 10 animals for periods varying from 10 to 50 min. During each procedure a continuous cortical electrogram was made, and scalp records were obtained at intervals post-operatively. 2. 2. A decrease in electrical potential occurred within 1 min. following occlusion, in all but four animals. This decrease was not proportional to the size of the infarct which subsequently developed. 3. 3. In 9 of the 10 animals with temporary occlusion, some restoration of potential occurred within 30 min. following the termination of occlusion. In 5 of these the potential returned to the pre-operative level in this period. 4. 4. In about two-thirds of the post-operative scalp records there was a persistent diminution of amplitude over the region of the infarct or over the entire right hemisphere. 5. 5. Slow waves, appearing in only two animals during operation, were consistently present post-operatively in about one-half of the animals. 6. 6. Abnormal rhythmic patterns appeared in two-thirds of the animals, but clinical seizures were observed in only three, whose middle cerebral arteries were occluded for 40 min., 40 min. and 30 min. respectively. In each instance these seizures involved the contralateral arm and face. 7. 7. Epileptiform activity appeared in the EEG from the contralateral as well as the ipsilateral side in 3 animals.