PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “CORONARY VESSELS”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 685 records · Page 38Linked to original sources
PubMed1976

Unmasking of sympathetic vasoconstruction of the coronary vessels after acute administration of reserpine to dogs.

Acute intravenous administration of reserpine or pretreatment of dogs with Segontin selectively abolished coronary vasodilation and unmasked a constrictor response to stimulation of the cardiac sympathetics. In view of earlier findings of separate coronary vasomotor and cardiostimulatory sympathetic innervation, the results are interpreted to indicate the existence of reserpine-resistant short (vasomotor) and reserpine-sensitive long (cardiostimulatory) sympathetic postganglionic neurons.

Animals↗
PubMed1986

Adrenergic coronary tone during submaximal exercise in the dog is produced by circulating catecholamines. Evidence for adrenergic denervation supersensitivity in the myocardium but not in coronary vessels.

The goal of this study was to test the hypothesis that circulating catecholamines are primarily responsible for alpha-adrenergic coronary vasoconstriction during submaximal exercise. The experimental series consisted of chronic studies in which a regional left ventricular sympathectomy was performed with phenol. Myocardial perfusion to the innervated and sympathectomized left ventricular regions was measured in these animals during (1) a control period, (2) treadmill exercise, (3) exercise during beta-adrenergic blockade, and (4) exercise during combined alpha- + beta-adrenergic blockade. We found no differences in myocardial perfusion between the innervated and sympathectomized regions or the transmural distribution of perfusion during any of these interventions. Thus, there is no evidence for neurogenic alpha-adrenergic coronary vasoconstriction. However, during exercise in the presence of alpha- and beta-blockade, coronary resistance (mmHg X min X 100 g/ml) was significantly less in both the innervated (0.65 +/- 0.07) and sympathectomized (0.68 +/- 0.07) regions than during beta-blockade, 0.90 +/- 0.17 and 0.89 +/- 0.16, respectively. This suggests that coronary alpha-adrenergic constriction was produced by circulating catecholamines. This concept of humorally mediated, alpha-adrenergic coronary vasoconstriction was strengthened by in vivo and in vitro studies that demonstrated that alpha-adrenergic supersensitivity of the coronary vasculature was not present. Myocardial beta-adrenergic supersensitivity was observed in the phenol regional sympathectomy model; however, this effect was blocked by propranolol (1 mg/kg). This indicates that alpha-adrenergic vasoconstriction in both myocardial regions during submaximal exercise is produced by circulating catecholamines. The major conclusion of this study is that, during submaximal exercise in the canine, alpha-adrenergic coronary vasoconstrictor tone is predominantly due to circulating catecholamines rather than direct neural effects.

Animals↗
PubMedDate not supplied

[Prevention of stress-induced changes in coronary autoregulation of vasodilative reserve of the coronary vessels and contractile function of the isolated heart with small doses of thyroid hormones].

The possibility to restrict stress disturbances of coronary blood flow and contractile myocardium function with small doses of thyroid hormones has been studied on 46 hearts of female rats isolated by the Langendorff method. It is found that small doses of thyroidin increase the force of systoles and adequately increase relative coronary blood flow, coronary reserve vasodilatation, significantly prevent stress disturbances of coronary autoregulation, the force and rate of the myocardium contraction and relaxation, that restricts disproportion between contractive function and coronary blood flow.

Animals↗
PubMed1990

[Study of the role of the endothelium in the development of coronary vessel reactions of different etiologies].

Experiments were made in dogs under the conditions of blood autoperfusion of one of the left coronary artery branches. Chemical removal of the endothelium with saponin was shown to lead to abnormal coronary reactivity, eliminate dilatory and give rise to constrictive responses to ATP, acetylcholine, histamine. After an initial coronary dilatation, hypoxic hypoxia resulted in a pronounced increase in coronary resistance and a reduction in coronary flow in intact animals. Preliminary deendothelization of the coronary artery caused disappearance of a dilatatory phase of the reaction, acceleration and enhancement of coronary constriction in response to hypoxia.

Animals↗
PubMed1982

[Contractility of ischemic and intact regions of the myocardium during experimental occlusion of the coronary vessels].

In acute experiments on 32 dogs the authors studied the time course of the contractile function of the myocardium after coronary occlusion in the area of ischaemia and in segments of the left ventricle far removed from the ischaemic zone. Local contractility was studied with the aid of M-echographic method through changes in the thickness of the ventricular wall during the contraction. As a result of experimental investigation the authors distinguish 3 types of myocardial asynergy: hypokinesia, hypokinesia with elements of dyskinesia in the initial part of the ejection period and dyskinesia. A quantitative assessment of the degree of asynergy is offered on the strength of the amplitude of movement of the ischemized wall, percentage of its maximum systolic thickening and the local phase structure of the myocardial contraction. The most sensitive index of the state of general contractility of the left ventricle after limited ischaemia of the myocardium proved to be the end diastolic pressure and the ratio between the stroke work of the left ventricle and the end diastolic pressure.

Animals↗
PubMed1993

[Noninvasive identification of left main and triple vessel coronary artery disease using dipyridamole thallium scintigraphy].

The diagnostic value of dipyridamole thallium scintigraphy for the noninvasive identification of left main (LM) and triple vessel (TV) coronary artery disease (CAD) was evaluated in 615 consecutive patients with known or suspected CAD. One hundred thirty-nine patients had LM or TVCAD; the remaining 476 patients had limited CAD (double vessel CAD in 112, single vessel CAD in 235, insignificant lesions in 129). Patients with LM or TVCAD, compared to those with limited CAD, had a higher incidence of diffuse slow washout (58 vs 20%, p < 0.0001), extensive fixed defects (21 vs 6%, p < 0.0001) and extensive reversible defects (32 vs 8%, p < 0.0001). During dipyridamole loading, the incidence of chest pain was higher (65 vs 41%, p < 0.0001), and the magnitude of ST depression was greater (0.16 +/- 0.14 vs 0.04 +/- 0.07 mV, p < 0.001) in patients with LM or TVCAD than in those with limited CAD. Stepwise discriminant analysis using scintigraphic imaging achieved a sensitivity of 69%, a specificity of 79%, and an accuracy of 77% for diagnosing patients with LM or TVCAD. After including clinical markers of ischemia during dipyridamole loading, multivariate analysis revealed an improved diagnosis with a sensitivity of 71%, a specificity of 85%, and an accuracy of 82%. These results clearly show the usefulness of scintigraphic imaging as well as the significance of careful assessment of clinical markers of ischemia during dipyridamole loading for the noninvasive identification of LM and TVCAD.

Adult↗