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Biomedical subjects

M A Barletta

Publications and source records attributed to M A Barletta.

10 recordsLinked to original sources
PubMed1991

Magnesium protection against anthracycline toxicity in vitro.

The clinical usefulness of the antitumour agents daunomycin (DAU) and adriamycin (ADR) is limited by their secondary cardiotoxicity. The anthracycline compounds have a number of detrimental effects on the biochemical and morphological integrity of the cardiac cell which may be related to the accumulation of cellular calcium. Using a model of spontaneously beating, cultured neonatal rat cardiomyocytes, we examined the cardioprotective role of magnesium during 2 hours of exposure to 10, 25 or 50 micrograms/ml DAU. A significant preservation of myocyte membrane integrity and cellular morphology was observed with the addition of equimolar magnesium. Magnesium opposes the actions of calcium in a number of tissues and it may be this calcium antagonist action that makes magnesium effective in DAU toxicity.

Animals↗
PubMed1978

Modified technique using perfused isolated guinea pig lung to determine effect of an aerosol constituent on pulmonary dynamics.

Polyethylene glycol 400, a commonly used plasticizer in many cosmetic aerosol hair sprays, was tested to determine its effect on perfusion pressure, perfusion vascular flow rate, and tidal volume in the perfused isolated guinea pig lung. Negative pressure was maintained within the chamber housing the intact lungs, and initial perfusion of the pulmonary vasculature was accomplished via the right side of the heart in situ after guinea pigs were sacrificed by decapitation. Polyethylene glycol 400 was injected into the pulmonary arterial system in doses of 0.01-30 microgram/ml after pretreatment with isoproterenol (1 microgram/ml). Isoproterenol was then readministered, followed by nebulized doses of the cosmetic chemical into the trachea at 0.3, 3, and 30% concentrations. Nebulized polyethylene glycol 400 was also administered in 50, 70, and 90% concentrations. Polyethylene glycol 400 significantly increased perfusion pressure and flow rate after injection into the pulmonary arterial system of the isolated lung. In addition, nebulized administration in concentrations of 0.3-30% significantly increased the perfusion flow rate; following the 50-90% nebulized doses, a significant increase in both perfusion pressure and flow rate was observed. Tidal volume decreased, regardless of the route of administration, as increasing doses of the cosmetic constituent were delivered to the isolated lung.

Aerosols↗
PubMed1978

Hemodynamic alterations in isoproterenol-induced cardiac arrhythmias in corticoid-treated rats.

Hemodynamic alterations were studied to determine their role in isoproterenol-induced cardiac arrhythmias in the desoxycorticosterone acetate--saline-treat rat. Since epinephrine, a catecholamine possessing an alpha-adrenergic receptor agonist component, was considerably less potent as an arrhythmogenic agent, an elevation in blood pressure was thought to be protective against arrhythmias. Both albuterol, a beta2-adrenergic agonist, alone and epinephrine administered following tolazoline, an alpha-adrenergic blocking agent, decreased blood pressure to that of isoproterenol but failed to elicit significant arrhythmias. Phenylephrine administered prior to isoproterenol resulted in significant arrhythmias despite the maintenance of mean blood pressure at normal levels. The study shows that blood pressure alterations are not important in the etiology of isoproterenol-induced arrhythmias in the corticoid-pretreated rat.

Adrenal Cortex Hormones↗
PubMed1978

Effects of pharmacological intervention on infarct size following induced myocardial infarction in rats.

Several therapeutic agents that alter infarct size were administered to rats with myocardial infarcts induced by electrocauterization. The myocardial tissue damage and infarct size correlated well with the creatine phosphokinase myocardial band activity, and these markers were utilized to assess the action of the therapeutic agents on myocardial tissue damage. Hyaluronidase, insulin, potassium chloride, and isoproterenol increased myocardial tissue damage whereas heparin and prednisolone administration resulted in decreased myocardial tissue damage after induced myocardial infarction in rats.

Animals↗
PubMedDate not supplied

Protective role of magnesium in catecholamine-induced arrhythmia and toxicity in vitro.

The present study examined the arrhythmogenic and toxic liability of isoprenaline, noradrenaline and adrenaline using a model of spontaneously beating, cultured rat cardiomyocytes. The cardioprotective role of magnesium (Mg) was also evaluated. Following two hours of exposure to 0.1-2.7 mM doses of isoprenaline, noradrenaline or adrenaline, there were dose-dependent increases in the incidence of arrhythmia and decreases in beating activity. Myocyte LDH release increased 64-189% while total myocyte K+ and Mg2+ decreased 13-60% at high catecholamine doses. Levels of the secondary messengers IP3 and cAMP were also increased. Equimolar Mg (0.9 mM) significantly reduced the incidence of catecholamine arrhythmia while preserving beating activity, membrane integrity and electrolyte levels. Mg proved to be in vitro a potent antiarrhythmic and cardioprotective agent which is likely to exert its beneficial effects via antagonism of calcium.

Animals↗