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Biomedical subjects

D T Zborowska-Sluis

Publications and source records attributed to D T Zborowska-Sluis.

14 recordsLinked to original sources
PubMed1980

Effect of acute sympathectomy by epidural anesthesia on the canine coronary circulation.

The effects of reversible sympathetic neural blockade of the canine myocardium under control conditions and in the presence of decreased coronary blood flow and after myocardial infarction were investigated in 17 dogs. A multiple-microsphere technique was used to measure distribution of blood flow in the myocardium. Epidural blockade was associated with the following changes in the ratio of endocardial to epicardial blood flow: under control conditions, no change; after 50 per cent decrease in coronary flow, 18 per cent increase in endocardial/epicardial ratio; after myocardial infarction at unrestricted coronary flow, 43 per cent ratio increase; after myocardial infarction and 50 per cent decrease in coronary flow, 76 per cent increase of endocardial/epicardial ratio. These effects appear to be independent of systemic factors, and may result from alterations in tone of transmural resistance vessels. In addition, cervicothoracic epidural blockade resulted in a decrease in systemic pressure and an increase in coronary vascular resistance as myocardial oxygen demand decreased. When systemic pressure was restored these effects were abolished. In the presence of myocardial infarction, epidural blockade had less effect on systemic pressure and left ventricular filling pressure was decreased. With decreased coronary flow, sympathetic blockade redistributed coronary blood flow, favoring sympathetic blockade redistributed coronary blood flow, favoring the endocardium in both the normal and the infarcted heart.

Anesthesia, Epidural↗
PubMed1980

Effects of oral perhexiline on canine myocardial flow distribution.

Perhexiline maleate at a dose of 400 mg three times daily for 2 days administered to normal dogs altered the relative regional transmural resistance so that during reduced coronary flow the endocardium:epicardium (endo:epi) ratio is increased. In the presence of acute myocardial infarction heart rate was significantly lower and the endo:epi ratio of perfused areas was increased when coronary flow was normal. A linear relationship was observed between the endo:epi ratio and the concentration of perhexiline in plasma, and its monohydroxyl metabolite in plasma. The results suggest that the mechanism of action of the drug is due to redistribution of a limited coronary flow.

Animals↗
PubMed1979

The effect of myocardial force on coronary transmural flow distribution.

The role of myocardial force as a determinant of transmural coronary flow distribution was examined in the presence and absence of autoregulation by infusing calcium chloride into a segment of the left coronary system. The concentration of calcium used was adequate to increase force but did not alter coronary pressure or endoventricular pressure. No alterations in transmural gradients of flow were observed following increased regional force. These results suggest that increases in regional force are not of importance as a determinant of transmural blood flow.

Adenosine↗
PubMed1977

The role of coronary flow and pressure as determinants of myocardial oxygen consumption in the presence or absence of vasomotor tone.

When coronary flow was kept constant and coronary pressure increased by angiotensin or decreased by dipyridamole, myocardial oxygen consumption (MVO2) remained unchanged. When vasomotor tone was abolished by dipyridamole or was intact, changing coronary flow resulted in a change in MVO2 in the same direction as flow; this change in MVO2 was in part the result of a significant alteration in coronary oxygen extraction. These results suggest that coronary flow, but not coronary pressure is an important determinant of MVO2 both in the presence or absence of vasomotor tone.

Angiotensin II↗
PubMed1976

Myocardial tissue recruitment in the dog as determined by double tracer dilution method.

The amount of tissue perfused, as determined from the difference in volume of distribution between a diffusible indicator (125I-antipyrine) and an intravascular indicator (131 I-albumin) was measured at different values of coronary flow, perfusion pressure, and vasomotor tone in the working left ventricle of an open-chest dog. Coronary pressure and flow were regulated independently from the systemic circulation and coronary vasomotor tone was reduced by dipyridamole. At each flow vasomotor tone was assessed by using as a reference the maximal vasodilation induced by arrest of flow. Measured tissue space was considered to be related to the capillary surface area available for tracer diffusion and therefore to the number of perfused capillaries per volume of muscle. A relationship between coronary blood flow and tissue volume was observed. It was found to be independent of vasomotor tone. Vasodilation was found to increase available exchanging capillary surface at a constant perfusion pressure.

Animals↗
PubMed1975

The effect of acetazolamide on myocardial carbon dioxide space.

Carbon dioxide, water and vascular space were measured in the heart muscle of the dog before and after the administration of acetazolamide. In contrast to the skeletal muscle whose CO2 space was markedly reduced by acetazolamide, cardiac muscle CO2 space was only minimally reduced. This suggests that cardiac muscle does not have extravascular carbonic anhydrase. Its presence in skeletal muscle and absence in cardiac muscle probably relates to the differences in cell size between the two types of muscle and their differing degree of vascularity.

Acetazolamide↗