Morphometric characterization of left ventricular myocardial cells of male rats during postnatal development.
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Biomedical subjects
Publications and source records attributed to H Guski.
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The authors describe device and functioning of a new efficacious membrane thin-layer oxygenator, specially developed for experiments on the isolated hearts of small animals. Compared with customary oxygenators with direct oxygenation, advantages arise from the separation of gas and perfusion solution, and its small volume for filling (7,5 ml). The diffusion capacity of the oxygenator (exchange surface 980 cm2) was tried by means of a hemoglobin-free modified Krebs-Henseleit solution with various flow values at 37 degrees C, depending on the gage of the layer. At the optimal gage of 0,15 mm and a flow value of 15 ml/minute a perfusion solution can be oxygenated from 0 to 570 torr, and an airequilibrated solution up to 646 torr. Measurements of oxygen consumption in the isolated perfused rat heart proved that the diffusion capacity of the membrane thin-layer oxygenator will suffice the oxygenation of the coronary minute volume of the arrested heart according to Langendorff as well as of the working heart according to Morgan. Primarily this oxygenator is useful for experimental organ perfusion in metabolic and functional tests, and organ preservation. Its functioning principles, however, also permit its use as thins-layer dialysator.
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A method is described for producing a localized coronary artery stenosis by tieing two threads around the Ramus descendens of the left coronary artery, which produces progressive cell proliferation of the vascular wall. Studies on 102 male Wistar rats (70 experimental and 32 sham-operated control animals) have shown coronary artery stenosis narrowing the lumen by more than 50% (up to and exceeding 90%) to develop after 7 days in 30% of the animals, after 14 days in 75%, and after 21 days (postoperatively) in 100%. In about one-third of the cases subtotal infarction in the supply area of the left coronary artery occured as a result of post-operative damage to the coronary artery with obturating thrombosis. The induction of effective coronary stenosis limiting the coronary reserve offers possibilities for further experimental studies on the role of relative coronary insufficiency in the pathogenesis of myocardial infarction.
A stenosing proliferation of the vascular wall was produced by exposing the Ramus descendens of the rat's left coronary artery to continued mechanical stimulation. Two weeks after the operation the hearts were perfused according to a modified Langendorff method, and the flow rate was measured under aerobic conditions and following short-time anoxia. Under either experimental conditions, the flow rate proved to be significantly decreased.