摘要:

Several vasoconstrictor drugs and reserpine administered into a cerebral lateral ventricle inhibited the reflex pressor response to occlusion of the common carotid arteries in both anesthetized and unanesthetized dogs. This effect was opposed by central administration of the vasodilator drugs, nitroprusside and histamine. Serotonin, norepinephrine and their precursors, 5-hydroxytryptophan and 3,4-dihydroxyphenylalanine, and reserpine caused lowering of arterial pressure and slowing of heart rate as well as inhibition of the carotid occlusion response; angiotensin and vasopressin did not. The central inhibitory effect of norepinephrine was opposed by phentolamine; that of 5-hydroxytryptophan was not affected by lysergic acid diethylamide or its brom derivative.Cooling of cerebrospinal fluid, which presumably caused local vasoconstriction, also caused inhibition of the carotid occlusion response, hypotension and bradycardia, and these effects were counteracted by central injection of vasodilator drugs. Warming of cerebrospinal fluid, presumably associated with local vasodilation, opposed the central inhibitory effect of vasoconstrictor drugs and of reserpine.In view of the consistently opposite effects of vasoconstrictor and vasodilator drugs and procedures on central vasomotor sympathetic activity, it is tentatively concluded that these effects depend on change in local blood flow. The acute cardiovascular effects of reserpine of central origin are probably due to local decrease of tissue perfusion caused by serotonin, norepinephrine or other vasoconstrictor agent released from a bound to an active form.

ISSN:0009-7330    

出版商:OVID    

年代:1960

数据来源: OVID

摘要:

Pharmacodynamically induced changes in left ventricular work, using an intravenous infusion of Hypertensin, were studied in intact anesthetized dogs. Coronary and systemic hemodynamics and cardiac metabolism under a combined morphine- “Dial” -urethane-pentobarbital-sodium (MDUP) anesthesia were measured during the action of the drug. The significant hemodynamic changes induced were increased mean arterial pressure and increased left ventricular work. A greater cardiac lactate utilization during the Hypertensin infusion was the only change in cardiac metabolism. The oxygen tension in left ventricular venous blood was not reduced during the action of the drug.

ISSN:0009-7330    

出版商:OVID    

年代:1960

数据来源: OVID

摘要:

Hyperglycemia and hypoxia acidosis are known to occur during periods of shock. The plasma levels of catechol amines have been reported to be elevated during periods of shock. Injection of epinephrine or levarterenol can produce increments in blood glucose and have been shown to elicit a metabolic acidosis. In the present studies the effects of reducing circulating blood volume or infusion of lactic acid and of forced CO2inhalation on ventricular isometric systolic tension (VCF) and the cardiovascular response to test injections of levarterenol were studied. The experiments with a reduction in circulating blood volume and with lactic acid infusions resulted in a decrease in arterial pH. whole blood total CO2and whole blood CO2combining power. Concomitant with these changes there was a marked depression of VCF and the response to test injections of levarterenol. Correction of the acid-base changes with 2-amino-2-hydroxymethyl, 1, 3-propane diol resulted in an immediate improvement in VCF and in the response to levarterenol. This change occurred despite a greater increase in blood lactate levels. Anaerobic metabolism with lactate production leads to a decrease in total blood CO2and an increase in dissolved CO2. This decrease in the CO2-carrying capacity would lead to an increase in tissue CO2. Since the heart is markedly depressed by CO2, this increment could be largely responsible for the myocardial depression. The oxygen debt which the heart can incur is thought to be limited. Therefore, the build-up of CO2one of the end-products of aerobic metabolism, would depress oxidative metabolism according to the law of mass action. This hypothesis was further tested by forced CO2ventilation which resulted in a marked depression of VCF and the response to levarterenol. Correction of the respiratory acidosis by the administration of THAM which increased the CO2-carrying capacity of the blood resulted in an immediate improvement in VCF and the levarterenol response.

ISSN:0009-7330    

出版商:OVID    

年代:1960

数据来源: OVID

摘要:

The relationship between left ventricular end-diastolic pressure and circumference was studied in 27 open-chest dogs, utilizing a mercury-resistance gage to measure left ventricular end-diastolic circumference. In 6 experiments aortic pressure, cardiac output and heart rate were varied independently. Tachycardia above a rate critical for each heart elevated left ventricular eud-diastolic pressure for any given end-diastolic circumference. Hypothermia at a constant heart rate had a similar effect. The altered left ventricular end-diastolic pressure-end-diastolic circumference relationships resulting from tachycardia and hypothermia are believed to be related to the incomplete ventricular relaxation which occurs as the duration of diastole is encroached upon. Acute, spontaneous heart failure was accompanied by an augmented left ventricular end-diastolic circumference for any given end-diastolic pressure, an effect which may be considered to reflect an increase in myocardial extensibility. The relationship between left ventricular end-diastolic pressure and end-diastolic circumference was not modified either by changes of aortic pressure or of cardiac output. There was no constant relationship between the left ventricular end-diastolic circumference and the tension-time index. Indeed, it was possible to manipulate aortic pressure and cardiac output so that these 2 parameters moved in opposite directions. These observations are not consonant with the view that myocardial oxygen consumption is primarily dependent on end-diastolic fiber length.

ISSN:0009-7330    

出版商:OVID    

年代:1960

数据来源: OVID

摘要:

Extracellular tissue spaces are compared using inulin, sucrose, chloride and sodium in hearts perfused with Ringer-Locke solution by Langendorff's method. Also chloride and sodium spaces are given for unperfused, fresh hearts. From the inulin spaces the intracellular chloride, sodium, potassium and water concentrations in both perfused and unperfused heart chambers have been calculated. Data showing the specificity of the atrium and ventricles of the heart are presented.

ISSN:0009-7330    

出版商:OVID    

年代:1960

数据来源: OVID

摘要:

The histologic pulmonary vascular changes and the pulmonary arterial pressure changes which occur during the first 13 weeks of life have been studied in mongrel puppies. The histologic changes were based on measurements of the average lumen to wall ratios of arterial vessels 50 to 200 μ in diameter. The pulmonary arterial pressure changes were recorded by direct needle puncture of the main pulmonary artery in anesthetized thoracotomized animals. The average L/W ratios of all neonatal mongrel puppies from separate litters were less than 4.0, the boundary chosen to distinguish neonatal and adult pulmonary arterial vasculature. All puppies younger than 1 month had average L/W ratios below 4.0. Although average mean pulmonary arterial pressures were found to be near adult levels by age 1 week, the ratio of pulmonary to systemic arterial pressure, expressed as a percentage, did not consistently approach adult levels until 1 month of age. The dimensional evolution of small pulmonary arteries and the gradual decline in the ratio of pulmonary to systemic pressure toward near adult levels at 4 weeks suggested a cause-and-effect relationship between these 2 phenomena. Major operative procedures have been performed on puppies 3 to 5 weeks of age with survival. It is proposed that experimental pulmonary hypertension produced in 4-week-old mongrel puppies would closely approximate the situation of a high pressure congenital cardiac shunt in humans without excessive operative mortality.

ISSN:0009-7330    

出版商:OVID    

年代:1960

数据来源: OVID

摘要:

A decrease in the ATPase (heat stable) and 5-nucleotidase of atherosclerotic regions in human aortae has been demonstrated. An increase in the breakdown of TPN, as measured by phosphate release, of the atherosclerotic aorta as a whole has been shown. No change was observed in the breakdown of DPN, as measured by phosphate release, between the normal or atherosclerotic aorta. No reactivity for glucose-1 or glucose-6-phosphate or β-glycerophosphate was found in the intima or media. The possible implications in the development of atheroma are discussed.

ISSN:0009-7330    

出版商:OVID    

年代:1960

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1960

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1960

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1960

数据来源: OVID