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Biomedical subjects

H Fukuzaki

Publications and source records attributed to H Fukuzaki.

At least 289 records · Page 16Linked to original sources
PubMed1980

The effects of large doses of dexamethasone on myocardial contractility and calcium metabolism in experimental myocardial infarction.

Metabolic effects of dexamethasone (DX) on the noninfarcted functioning myocardium were studied in rabbits with experimental coronary artery ligation to evaluate the usefulness of glucocorticoids in acute myocardial infarction. Maximum active tension of noninfarcted area of the isolated perfused hearts was markedly reduced 6 hr, 2 days, and 5 days after ligation, associated with significant decreases in norepinephrine (NE) and cAMP contents, but with no changes in adenylate cyclase (AC) and cAMP phosphodiesterase (PDE) activities. Calcium content of mitochondrial fraction was considerably increased in the peri- and noninfarcted area without any changes in microsomal CA2+ or myocardial total Ca2+. Ca2+ uptake rate and Ca2+-dependent ATPase activity of the sarcoplasmic reticulum fraction from the operated hearts were markedly reduced. Intramuscular administration of DX (3 mg/kg body wt/day) for 2 days after operation significantly improved these reductions in myocardial function and metabolism. In normal hearts from animals without infarction, DX caused 48% elevation in basal cAMP level, marked reductions in mitochondria and microsomal Ca2+, and 26% decrease in PDE activity, although no changes in myocardial total Ca2+ AC activity and myocardial contractility were observed. NE-induced inotropic effects were markedly enhanced in both control and operated groups with DX treatment. These results indicated that large doses of DX would improve the reduced myocardial function and metabolism in acute myocardial infarction by increasing basal cAMP level and by its influence on intracellular Ca2+ available for cellular activity.

Animals↗
PubMed1979

Coronary collateral circulation as an important factor to modify the ischemic injury of the myocardium in coronary ligated dogs.

Effect of coronary ligation on epicardial and intramyocardial ST-segment voltage was investigated in 121 dogs. After ligation of the anterior descending coronary artery, marked ST-elevation, more than 2 mV, was detected in 102 dogs (Group-I) in epicardial lead of the area which was nourished by the ligated coronary artery. In 7 dogs (Group-II), coronary ligation produced negligible changes in ST-segment voltage in epicardial lead, while significant ST-elevation was observed in the leads of middle and inner layers of the myocardium. Systemic hemo-dynamic parameters showed no statistically significant difference between the 2 groups. Coronary collateral indices, however, revealed the significant difference between them. Systolic peripheral coronary pressure was 29.3 +/- 3.1 mmHg in Group-I and 59.2 +/- 10.6 mmHg in Group-II (P less than 0.05). Retrograde flow was also greater in Group-II (14.8 +/- 4.4 ml/min) than in Group-I (1.3 +/- 0.5 ml/min) (p less than 0.01). Diversion of retrograde flow produced a marked ST-elevation in Group-II. Restoration of retrograde flow to the myocardium immediately decreased the ST-segment voltage. These results suggest that spontaneously developed collaterals have an important function for the prevention of the occurrence of ischemic injury after coronary ligation in dogs.

Animals↗
PubMed1978

An experimental study on the role of coronary collateral development in preservation and improvement of contractile force in the ischemic myocardium.

Attempts have been made to demonstrate that the presence of coronary collateral development can preserve and improve the regional contractile force in the ischemic myocardium. Studies were carried out in dogs with developed collaterals and in control dogs. Contractile force was measured with strain-gauge sutured onto the ischemic and the border areas of the myocardium. After ligation of the anterior descending coronary artery, an augmentation of coronary collateral flow via the left circumflex artery was carried out by means of infusion pump up to two and a half fold level. In dogs with developed collaterals, contractile force decreased by 57.6 +/- 11.1% (p less than 0.01) in the ischemic area and 27.2 +/- 5.4% (p less than 0.01) in the border area after coronary ligation. The marked recovery of contractile force up to 63.5 +/- 20.4% (p less than 0.05) of control level in the ischemic area and 70.4 +/- 20.4% (p less than 0.01) in the border area was observed by the augmentation. In control dogs, however, contractile force decreased by 93.2 +/- 17.2% (p less than 0.01) in the ischemic area and 24.6 +/- 5.5% (p less than 0.01) in the border area after the ligation. The augmentation of coronary flow did not recover the depressed contractile force in both areas. These results indicated that the beneficial effect was observed only when the ischemic area was supplied by developed collaterals and closely correlated with the extent of coronary collateral development.

Animals↗
PubMed1978

Effects of graded coronary constriction on regional oxygen and carbon dioxide tensions in outer and inner layers of the canine myocardium.

This study was undertaken to investigate the effects of graded coronary constriction on regional gas tensions of the myocardium. In 12 open chest dogs, tissue carbon dioxide (PtCO2) and oxygen (PtO2) tensions were measured simultaneously in outer and inner layers of the myocardium using a mass spectrometer. In normal condition, higher PtO2 and lower PtCO2 were observed in outer layer than in inner layer. With application of coronary constriction, increase in PtCO2 and decrease in PtO2 were observed in both layers of the myocardium, but the response to the ischemic stimuli by applying coronary constriction in inner layer was different from that in outer layer. Severe coronary constriction, more than 90% in its diameter, was necessary to produce significant changes in both gas tensions in both layers of the myocardium. Decrease in PtO2 was found in the condition of less severe coronary constriction and to be greater in inner layer than in outer layer of the myocardium. In terms of the changes in PtCO2, inner layer was also more susceptible to the ischemic stimuli than outer layer. The greater and earlier elevation of PtCO2 in inner layer than in outer layer is regarded as one of the possible mechanisms of the reduction of myocardial contraction in the early stage of myocardial ischemia.

Animals↗
PubMed1975

Studies on pathophysiological effects of postalimentary lipemia in patients with ischemic heart disease.

The present studies were undertaken to elucidate the pathophysiological effects of postalimentary lipemia(PAL) induced by the intake of much animal fat in patients with ischemic heart disease(IHD) and the preventive measures against them. Results obtained were as follows: 1) Occurrence of augmentation of ischemic changes in ECG was demonstrated after fat intake. 2) After fat intake, lowering of arterial oxygen tension and heparin-induced increase in arterio-venous difference of oxygen tension in the forearm were observed. 3) PAL resulted in an acceleration of platelet adhesiveness as well as a shortening of plasms recalcification time and that of plasma prothrombin time. 4) It was revealed that red blood cells adsorbed fat on their membrane and then readily agglutinate together. 5) Removal of chylomicrons from the blood stream was accelerated by the intravenous injection of glucose. These results lead to the following conclusions: 1)PAL exerts a deleterious effect on the oxygen supply to the myocardium in patients with IHD and it is probably due to the disturbance of pulmonary function and that of oxygen diffusion and blood flow in the myocardium. 2) As one of preventive measures against the concurrent intake of carbohydrate in an appropriate quantity appears to be of use.

Agglutination↗
PubMedDate not supplied

Relationship between epicardial and intramyocardial ST-segment voltage and myocardial blood flow during graded coronary constriction in the dog.

This study was undertaken to examine the relationship between electrographic ST-elevation and regional myocardial blood flow during graded coronary constriction. Electrograms from the epicardial surface, outer and inner layers of the myocardium were recorded. Regional blood flow to the outer and inner layers of the myocardium was measured by means of a heat-clearance method. With the application of a coronary constriction, myocardial blood flow to the inner layer began to decrease with a 75% coronary constriction, while flow to the outer layer was maintained at near normal up to least an 80% coronary constriction. Non-linear squares curve of between ST-elevation and the decrease in myocardial flow resulted in y = 18.80 exp-0.06x - 0.02 in the outer layer and y = 9.22 exp-0.02x - 1.54 in the inner layer. Also the non-linear squares curve of between epicardial ST-elevation and the decrease in myocardial flow resulted in y = 50.91 exp-0.11 x + 0.04 in the inner layer and y = 10.29 exp-0.07 x + 0.03 in the outer layer. The standard deviations of the coefficients of the latter two equations were higher than those of the former two equations. The higher values indicated larger variations of the parameter coefficients and data points. These results clearly demonstrated that a regional intramyocardial electrogram more closely reflects local ischemia than does an epicardial electrogram.

Animals↗
PubMedDate not supplied

Fentanyl for sedation during upper gastrointestinal endoscopy.

The effects of sedation by intravenous fentanyl on the rate-pressure product (pulse rate x systolic blood pressure/100), arterial oxygen saturation, electrocardiographic change, and serum cortisol concentration were studied during gastroduodenoscopy in 84 patients randomized to receive fentanyl or no intravenous sedative (controls). Fentanyl administration increased the tolerance of patients and attenuated the endoscopy-induced rise in rate-pressure product and serum cortisol concentration. Desaturation of arterial oxygen was minimal and there was no difference in arterial oxygen saturation between the fentanyl group and the control group. Therefore, fentanyl appears to be a favorable sedative for upper gastrointestinal endoscopy, since its administration increased the tolerance of patients and decreased cardiac oxygen consumption.

Adult↗
PubMedDate not supplied

Incidence of fundic gland polyps in patients without familial adenomatous polyposis.

The incidence of fundic gland polyps was evaluated using a high-resolution videoendoscope. In 1388 upper gastrointestinal endoscopic studies, 26 cases of fundic gland polyps (1.9% of the studied cases) were found. None of these patients had evidence of familial adenomatous polyposis. Fifteen of these patients (58%) had a solitary polyp in the gastric body, most of which were small sessile polyps of less than 2 mm in diameter. The results of this study indicated that a small solitary fundic gland polyp is not a rare gastric lesion and that little relationship exists between these solitary fundic gland polyps and familial adenomatous polyposis.

Adenomatous Polyposis Coli↗
PubMedDate not supplied

Dilatation of coronary stenosis as the salutary effect of nitroglycerin in relief of myocardial ischemia in the dog.

To clarify the role of coronary responses to nitroglycerin (NTG) in relieving myocardial ischemia, we examined the effects of NTG in canine models of dynamic and fixed coronary stenoses. Application of coronary stenosis in the proximal left circumflex artery decreased resting coronary blood flow by approximately 40% and caused a significant depression of left ventricular (LV) dP/dt. During fixed coronary stenosis created with an externally applied constrictor device, intravenous NTG, 5 micrograms/kg, reduced mean aortic pressure by 12 +/- 1.1 mm Hg (mean +/- SEM, p less than 0.01) and coronary blood flow by 9 +/- 1.0% (p less than 0.01) but did not affect stenosis resistance and LV dP/dt. During dynamic coronary stenosis produced with an intraluminal microballoon occluder, intravenous NTG caused a marked increase in coronary blood flow by 40 +/- 8.3% (p less than 0.01) and a decrease in stenosis resistance by 62 +/- 9.3% (p less than 0.01), as compared with postocclusion values, concomitant with a significant improvement in LV dP/dt. Intracoronary infusion of NTG, 1.0 microgram/kg/min, had few systemic and coronary hemodynamic effects during fixed coronary stenosis, whereas intracoronary NTG increased coronary blood flow and reduced stenosis resistance, depending on its dose, during dynamic coronary stenosis. These results indicate that NTG is capable of increasing coronary blood flow and alleviating myocardial ischemia due to direct stenosis-dilating effects related to the vasomobility of the coronary stenosis.

Administration, Oral↗