Cardiovascular research
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Cardiovascular research · Jun 1993
Oxygen radical scavenging agents as adjuvant therapy with tissue plasminogen activator in a canine model of coronary thrombolysis.
Early thrombolysis can reduce infarct size and enhance the long term recovery of contractile function after acute myocardial infarction. These benefits of early reperfusion may be confounded, however, by platelet mediated reocclusion after initial lysis, and "reperfusion injury" mediated by oxygen derived free radicals. Superoxide dismutase (SOD)--as well as its action as a potent free radical scavenging agent--inhibits platelet aggregation in vitro. Thus our primary objectives were to determine whether SOD+catalase, given as adjuvant therapy with recombinant human tissue plasminogen activator, could inhibit platelet aggregation and thereby reduce the time to lysis and maintain arterial patency. Whether SOD+catalase enhanced myocardial salvage or improved acute recovery of contractile function in the setting of thrombosis/thrombolysis was also assessed. ⋯ Although SOD+catalase acutely attenuated platelet aggregation and slightly accelerated lysis, these agents failed to limit platelet mediated rethrombosis. Furthermore, SOD+catalase did not enhance myocardial salvage and did not improve acute recovery of contractile function after thrombosis/thrombolysis. Thus SOD+catalase given as adjuvant therapy with tissue plasminogen activator did not have a substantial beneficial effect on either the efficacy of thrombolysis or on "reperfusion injury" in this canine model.
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Cardiovascular research · May 1993
Comparative StudyLeukotrienes D4 and E4 produced in myocardium impair coronary flow and ventricular function after two hours of global ischaemia in rat heart.
Leukotrienes D4 and E4 are potent coronary vasoconstrictors and myocardial depressants. The aim was to investigate the contribution of myocardial leukotrienes to impairment of coronary flow and recovery of contractile function in rat hearts subjected to 2 h of global ischaemia. ⋯ Leukotrienes are endogenously produced by the heart, and this production is significantly increased after global ischaemia and reperfusion. Reversal of significantly increased coronary vascular resistance coupled with improved functional recovery in hearts treated with LY171883 demonstrates an important contribution of endogenously produced leukotrienes to coronary vascular impairment and functional stunning of the globally ischaemic, reperfused heart.
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Cardiovascular research · May 1993
Estimation of left ventricular elastance without altering preload or afterload in the conscious dog.
The aim was to determine the slope (EES) of the left ventricular end systolic pressure-volume line (ESPVL) without altering preload or afterload in conscious dogs. ⋯ EES calculated from one beat is similar to EES determined from variably loaded left ventricular loops and responds appropriately to inotropic stimulation. This technique provides a reasonable method to calculate EES from left ventricular pressure and stroke volume without altering preload or afterload.
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Cardiovascular research · Mar 1993
Hypoxia induced disruption of the cardiac endothelial glycocalyx: implications for capillary permeability.
The aim was to determine the effect of hypoxia on the ultrastructure of the endothelial glycocalyx of cardiac capillaries. ⋯ The endothelial cell glycocalyx of continuous capillaries is sensitive to changes in PO2. The disruption of this surface coat may explain the reported increase in capillary permeability in hypoxia.
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Cardiovascular research · May 1992
ReviewEffects of drugs on body venous tone, as reflected by mean circulatory filling pressure.
The venous system is supremely important in the control of cardiac output. Drugs which affect the venous system have profound effects on haemodynamics. This review comments on the methods available for the determination of venous compliance, resistance, and unstressed volume and describes the mean circulatory filling pressure (MCFP) technique, its usefulness and limitations. ⋯ Mathematically, MCFP is inversely proportional to vascular compliance while experimentally, it is a primary determinant of venous return. The MCFP technique provides a reproducible and relatively non-traumatic means for the estimation of body venous tone in conscious and anaesthetised animals. Drugs examined by this technique include alpha and beta adrenoceptor agonists and antagonists, ganglionic blockers, vasoactive peptides (endothelin, vasopressin, angiotensin, neuropeptide Y), and vasodilators (hydralazine, nitroprusside, glyceryl trinitrate, calcium antagonists, and MCI-154).