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Biomedical subjects

L Merlo

Publications and source records attributed to L Merlo.

15 recordsLinked to original sources
PubMed1979

[Effects of dopamine, noradrenaline and isoproterenol on pulmonary circulation in anesthetized dogs].

Experiments were performed on 19 anaesthetized open-chest dog instrumented with polyethylene catheters inserted: into the aorta, in pulmonary artery and in left atrium and with an electromagnetic flow-transducer placed around the ascending aorta in order to record : systemic arterial and pulmonary pressures, mean left auricular pressure and phasic aortic flow. Heart rate, stroke volume, total systemic and pulmonary resistance, cardiac work were moreover calculated. Each dog was given intravenously by slow infusione : Dopamine (micrograms 5--10--20/kg/min/ 5 min), Isoproterenol (microgram 0.125--0.25--0.5/kg/min/5 min) and Norepinephrine (microgram 0.25--0.5--1 /kg/min/5 min). Results obtained on systemic hemodynamics agree with those reported by many other investigators. On pulmonary circulation : Isoproterenol, at the tested doses, elicited vasodilator effects, Norepinephrine increased total pulmonary resistance but not pulmonary vascular resistance, while Dopamine did not modify or slightly reduced vascular pulmonary tone.

Animals↗
PubMed1979

Acute clinical tolerance of creatinol O-phosphate.

Acute clinical tolerance to N-methyl-N-(beta-hydroxyethyl) guanidine O-phosphate (creatinol O-phosphate, COP) was investigated in volunteer human subjects without heart or renal disease and without other serious illness. COP was administered i.v. at three different dosages, 1020 mg (group A), 2040 mg (group B) and 3060 mg (group C), in comparison with a placebo (group D). Arterial pressure, heart rate, ECG pattern and a complete blood analysis showed no change at any COP dosage, with the exception of blood phosphate, which increased in groups B and C. Cumulative urinary excretion of phosphate and creatinine and diuresis increased, whereas other urine parameters did not change. The phosphate and creatinine increases derived from the COP molecule and the increase in diuresis from a simple osmotic process required to dilute the phosphate in the tubular fluid. All these alterations were statistically significant and dose-related with COP and had been expected. COP proved to be a very well tolerated drug without any evident side effect.

Adolescent↗
PubMed1979

The action of creatinol 0-phosphate on the inotropic effect of isoprenaline in isolated rat atria and in anesthetized dogs.

The action of N-methyl-N-(beta-hydroxyethyl) guanidine O-phosphate (creatinol O-phosphate) was studied on the contractility of the heart, in vitro on isolated rat atria and in vivo in anesthetized dogs. Creatinol O-phosphate was without action on the contractility of isolated rat atria stimulated by isoprenaline 10(-8) mol/l which produced the maximum inotropic effect. Creatinol O-phosphate increased the contractility evoked by isoprenaline 10(-5) mol/l and impaired the development of the negative inotropic effect evoked by prolonged treatment with this large dose. In dogs, creatinol O-phosphate pretreatment increased the positive inotropic effect of large but not low isoprenaline dosages. It is concluded that creatinol O-phosphate increased the contractile efficiency of the heart submitted to the action of an excess of catecholamines.

Animals↗
PubMed1978

Hemodynamic and metabolic changes induced by temporary clamping of the thoracic aorta.

Numerous authors reported a significant deterioration of heart function induced by aortic cross-clamping. Nevertheless, the aorta has been clamped during various surgical procedures without any complication. We studied the hemodynamic and metabolic variations induced by 20 min thoracic aorta cross-clamping in 6 open-chest dogs. During clamping the most striking modifications were an increase in coronary blood flow of over 65%, an increase in cardiac work of over 77% and an increase in total peripheral resistances of over 68% compared to base values. No significant variations were found in the heart rate and cardiac index. Metabolic parameters, such as O2 consumption and lactate consumption increased significantly during the clamping period. The increase in lactate consumption and the progressive and continuous improvement in oxygenation indexes (lactate/pyruvate, redox potential, excess of lactate) proved the absence of any myocardial anoxia during this period. Within 15--30 min after declamping all hemodynamic and metabolic parameters reverted to values close to basal values. These data strongly suggest that the mammalian heart can tolerate this procedure satisfactorily for a limited period of time. In clinical settings, one should consider the base conditions of the cardiovascular system before transposing these conclusions.

Animals↗
PubMed1978

Effects of creatinol-O-phosphate (COP) on haemodynamics and cardiac metabolism in conscious and anaesthetized dogs.

The effects of creatinol-O-phosphate (COP, Aplodan) have been studied on haemodynamics and cardiac metabolism of virtually normal heart (conscious dogs with electromagnetic probes chronically implanted) and progressively failing heart (open chest anaesthetized dogs). The results obtained show that COP in both series of experiments increased cardiac work and improved some myocardial metabolic parameters (delta redox potential across the heart, lactate/pyruvate ratio, excess lactate) probably by enhancing the myocardial O2 supply-consumption ratio, and consequently increasing the amount of O2 available for energetic reactions in the cardiac muscle and possibly in other tissues as well.

Animals↗
PubMed1976

Coronary blood flow and myocardial O2 consumption in hypertrophied cardiac muscle in dogs.

In dogs with experimental cardiac hypertrophy in resting conditions, coronary blood flow and myocardial O2 consumption increased proportionately to the cardiac mass; coronary flow and O2 consumption per gram of myocardium, therefore, ranged within normal values. The coronary reserve, neasured as the percentage increase in the coronary blood flow from rest till peak flow during reactive hyperaemia, was noticeably reduced, because it was partially utilized, even at rest, and consequently the possibility of an increase in flow after exercise or stress was diminished.

Animals↗
PubMedDate not supplied

Haemodynamics at rest and under effort in chronic arteriovenous fistulae (AVFs).

Latero-lateral femoro-femoral arteriovenous fistulae (AVFs) were surgically created in mongrel dogs. After 7-9 months during which the dogs were trained on a treadmill, devices suitable for recording arterial pressure and aortic and coronary flow were chronically implanted. Haemodynamic parameters of the dogs were controlled either at rest or after effort, keeping AVFs open or manually closed. The results, when statistically processed, showed that haemodynamic changes induced by occlusion of AVFs at rest and under effort are similar from a qualitative point of view, but considerably more marked after muscular exercise. Under effort the shunt index calculated rose to a higher extent than cardiac output. The decrease in heart rate after AVFs occlusion was significantly correlated with flow in the fistulae. However, the Nicoladoni-Branham phenomenon ought to be used for indirect evaluation of the shunt flow.

Animals↗