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Biomedical subjects

F Piccinini

Publications and source records attributed to F Piccinini.

At least 55 records · Page 3Linked to original sources
PubMed1991

Effect of flunarizine on the delayed cardiotoxicity of doxorubicin in rats.

The calcium antagonist flunarizine (FLN) was tested for its ability to prevent doxorubicin (DXR)-induced cardiotoxicity in the rat. A cumulative dose of 9.0 mg/kg of DXR was administered i.v. over a period of 1 week. FLN (10 mg/kg/day i.p., 6 days/week) was administered according to two different time schedules, covering respectively the first and last 4 weeks after the beginning of DXR treatment. The two schedules were adopted to assess whether early and/or delayed DXR-induced cardiotoxic effects were affected by FLN. The development of cardiac toxicity was monitored by ECG recordings. The animals were sacrificed 8 weeks after the beginning of DXR treatment. The contractile performance of isolated atria and the morphological pattern of left ventricular fragments were subsequently evaluated. The early administration schedule of FLN was shown to be ineffective in preventing DXR-induced cardiotoxicity and in some cases was actually found to potentiate the effects of DXR. In contrast, the histological evaluation of ventricular preparations from rats treated with DXR and FLN according to the delayed time schedule showed a significant improvement with respect to hearts from animals treated with DXR alone. An inhibition of the delayed calcium overload occurring after DXR administration has been proposed as a possible mechanism for this protective action.

Animals↗
PubMed1991

Protective effects of spin-trapping agents on adriamycin-induced cardiotoxicity in isolated rat atria.

Adriamycin (ADR) is known to exert a severe negative inotropic effect on isolated myocardial preparations; a role for free radical generation has been hypothesized. Spin-trapping of free radicals has been extensively exploited in ESR studies, both in cell-free systems and in intact tissues. The interaction between spin-traps and free radicals should in principle stop the reaction cascade leading to cellular damage. Based on this hypothesis, the possible cardioprotective action of three spin-trapping agents, 5,5-dimethyl-l-pyrroline-N-oxide (DMPO), N-tert-butyl-alpha-phenylnitrone (PBN) and alpha-(4-pyridyl 1-oxide) N-tert-butylnitrone (POBN), was tested on isolated rat atria incubated in the presence of ADR; maximal non-cardiotoxic concentrations were used (50, 10 and 50 mM respectively) in order to achieve a maximal spin-trapping effect. A varying degree of protection was observed with the three compounds, directly correlated to their hydrophobicity, as assessed by chloroform/water partition coefficients. It is proposed that ADR-induced free radical generation is responsible for the acute cardiotoxic effects of the drug; this seems to be a site-specific mechanism restricted to one or more hydrophobic cellular compartment/s, since only lipophilic spin-trapping agents are able to prevent the development of the negative inotropic effect of ADR.

Animals↗
PubMed1990

Effect of angiotensin II on the antitumor activity and cardiotoxicity of doxorubicin.

The effects of angiotensin II (AII) on the antitumor activity and cardiotoxicity of doxorubicin (DXR) were tested in rats bearing Walker 256/A carcinoma. The animals received 2, 4 or 6 mg/kg of DXR as a bolus i.v. injection, with or without a concurrent i.v. infusion of 2 micrograms/kg/min of AII, starting 1 h prior to DXR administration for a total of 6 h. Neither the antitumor activity, nor the myocardial toxicity of DXR, as assessed by ECG evaluation (Q alpha T duration), were affected by AII at the tested dose. 100% of the animals receiving 6 mg/kg of DXR with or without AII were cured from the tumor, but subsequently some of them developed toxic signs and eventually died within the 12th week after treatment. Rats receiving DXR + AII showed a higher long-term survival than those receiving DXR alone; therefore, a possible interference with other DXR-induced side effects, such as nephrotoxicity, is hypothesized.

Angiotensin II↗
PubMed1990

Cardiotoxicity and antitumor activity of a copper(II)-doxorubicin chelate.

The cardiotoxic and cytotoxic effects of the Cu(II)-doxorubicin (DXR) complex [Cu(DXR)]n are compared with those of the parent drug. It is shown that 10(-4) M [Cu(DXR)]n has no depressant effects on isolated rat atria, in contrast with an equimolar concentration of the parent drug. No differences were found between the cytotoxic activities of the Cu(II) complex and free DXR on B16 melanoma and HeLa cells. A reduced penetration of the polymeric [Cu(DXR)]n into the myocardial cells as compared with the free drug was invoked to account for the absence of cardiotoxicity of the DXR complex. On the other hand, the observation that copper-complexation does not affect the cytotoxicity of the drug suggests that extracellular as well as intracellular mechanisms may be involved in the development of its antitumor activity.

Animals↗
PubMed1990

A new approach to the direct detection of free radicals in the intact myocardium.

A new method for the direct ESR detection of free radicals in rat myocardial tissue is described. Isolated rat atria are continuously monitored for heart rate and contractile force; at the end of the experimental period the beating organs are inserted into quartz ESR tubes and immediately frozen in liquid nitrogen. Spectra obtained from these preparations show the presence of very weak radical signals. When ESR spectra are recorded on samples obtained from pools of rat atria pulverized under liquid nitrogen, the radical lines are markedly stronger than those observed for intact organs; contaminating metals are also frequently detected. These findings indicate that crushing or grinding procedures carried out under liquid nitrogen produce artifactual ESR active species. The new method described in the present paper does not involve mechanical interventions and therefore should yield reliable artifact-free results.

Animals↗
PubMed1990

Effect of glutathione and N-acetylcysteine on in vitro and in vivo cardiac toxicity of doxorubicin.

The effects of two sulfhydryl compounds, glutathione (GSH) and N-acetylcysteine (NAC), on the cardiotoxicity of doxorubicin (DXR) were tested on in vitro and in vivo models. DXR was administered to rats as 4 weekly i.v. doses of 3 mg/kg. GSH (1.5 mmoles/kg), given i.v. 10 min before and 1 hr after DXR, was found to prevent the development of the delayed cardiotoxic effects of DXR, as assessed by electrocardiographic and mechanical parameters, as well as by histological examination of left ventricular preparations. In contrast, equimolar oral doses of NAC (1 hr before and 2 hrs after DXR) were found to be ineffective. Both GSH and NAC prevented the negative inotropic effect produced by DXR on isolated rat atria. A good correlation exists between the cardioprotective effects of the two agents and their ability to enhance the non-protein sulfhydryl group content of the myocardium. Differences observed in vivo between GSH and NAC might be accounted for by pharmacokinetic factors.

Acetylcysteine↗
PubMed1989

Reduction of myofibrillar ATPase activity and isomyosin shift in delayed doxorubicin cardiotoxicity.

The aim of this study was to determine whether variations of isomyosin expression occurred during doxorubicin-induced cardiomyopathy. A suitable experimental model in which pure delayed cardiotoxic effects could be easily studied was adopted. Young adult female Sprague Dawley rats received 9 mg/kg of doxorubicin (DXR) i.v. divided into three subdoses of 3 mg/kg every third day. Control animals received equal volumes of saline. The animals were examined 9 weeks after treatment. At this time the animals treated with DXR showed ECG alterations, reduction of body weight and a marked decrease of both atrial and ventricular mass, but were still fully hemodynamically compensated. Loss of myofibrillar material could be documented by the reduced recovery of myofibril and myosin. The contractile response of papillary muscles isolated from the right ventricle of treated animals was markedly impaired. Ca-Mg-activated and Mg-activated myofibrillar ATPase activity and Ca-activated myosin ATPase activity were determined on ventricular myocardium of control and treated animals. Both myofibrillar and myosin ATPase activities were found to be significantly reduced. Pyrophosphate gel electrophoresis of purified myosin was carried out. The isomyosin pattern of DXR-treated animals showed a pronounced shift towards V3, the percent of alpha heavy chains being 54.6% in treated rats (80.5% in control rats). This isomyosin shift can explain the reduced myofibrillar and myosin ATPase activity found in treated animals.

Adenosine Triphosphatases↗
PubMed1988

Effect of calcium inhibitors and calcium mobilizers on doxorubicin accumulation in rat myocardial tissue.

The effect of four calcium-modulating agents on myocardial doxorubicin (DXR) accumulation was studied: the calcium-inhibitors verapamil (0.1 microM), trifluoperazine (5 microM) and flunarizine (0.05 microM) and the calcium-mobilizer taurine (50 mM). Myocardial cells of isolated Langendorff rat hearts receiving the drugs showed a significantly enhanced 14C-DXR uptake. These observations are in contrast with the hypothesis that DXR accumulation processes may be related to a decrease in calcium influx and suggest that a combined therapy with DXR and calcium-modulating agents might enhance the drug-induced cardiotoxicity.

Animals↗
PubMed1986

Relationship between doxorubicin-induced ECG changes and myocardial alterations in rats.

The aim of the present study was to evaluate the dose- and time-dependence of the effect displayed by doxorubicin (DXR) on the electrocardiogram (ECG) and to establish the relationship between structural alterations of the myocardium and ECG changes in rats administered DXR, at a dose of 1.5 or 3.0 mg/kg, every 3 days for a total of three administrations. The most interesting findings consisted of a dose-dependent, but reversible prolongation of the QRS complex, and in a dose-dependent and progressive irreversible increase in QaT and, in particular, in SaT duration. Furthermore, animals treated with the higher DXR dose showed a slight increase in serum K+ concentration and a significant decrease in serum Ca2+ levels. A good correlation was found between the morphologic score indicating the degree of observed tissue damage and SaT prolongation. These results therefore support the usefulness of measuring this ECG parameter for monitoring the development of DXR-induced cardiotoxicity in rats.

Animals↗
PubMed1986

Determination of doxorubicin and doxorubicin-3-ol in rat heart.

The discovery of a delayed form of DXR-induced cardiotoxicity raises the question whether the presence of the drug or of metabolites in myocardial cells is necessary for the development of cardiotoxicity. The present investigations deal with a new method for the determination of DXR and of its main metabolite, DXR-3-ol, in cardiac cells. Rat hearts "ex-vivo", isolated 24 h after i.v. administration of 6 mg/kg DXR and 20 micro C of DXR-14C, were perfused with ice-cold Tyrode solution, which releases anthracyclines from extracellular spaces. After homogenization DXR and DXR-3-ol were extracted from the cell at room temperature. The separation was carried out by HPLC; the recovery was about 95%, measured by the extracted radioactivity compared with that of the pellet residue.

Animals↗
PubMed1986

Myocardial contractility and heart pharmacokinetics of adriamycin following a single administration in rat.

A single administration of adriamycin (DXR) 6.0 mg/kg i.v. to rats brings about a biphasic impairment of the maximal myocardial contractile performance, measured as dF/dt of ex vivo isolated atria incubated in the presence of calcium concentrations varying up to 12 mM. The initial impairment of the contractile performance peaks 1 week after DXR administration and recovers within 3 weeks (acute phase of cardiotoxicity). After this time and up to the end of the observation period (8 weeks after treatment), delayed cardiotoxicity occurs, showing a progressive and irreversible impairment of the contractile performance of the atria. This behaviour parallels the previously shown ECG and morphological abnormalities. Tissue determinations of DXR showed that the drug is present in myocardium during the acute phase of cardiotoxicity, while the metabolite adriamycinol is not detectable 1 week after DXR administration. These data show that the presence of DXR and/or metabolites in heart muscle is not necessary for the delayed form of cardiotoxicity to become apparent and suggest that this form of cardiotoxicity is related to a mechanism different from that involved in acute cardiotoxicity.

Animals↗
PubMed1986

Effect of suloctidil on cerebral circulation patterns of conscious rabbits.

Suloctidil (SUL) produces calcium antagonistic and antispasmodic effects on peripheral and pial arteries. The present studies were performed with the aim of evaluating the action of SUL on cerebral blood flow (CBF), which was taken as an index for evaluating the cerebral circulation. The drug was administered by rapid intravenous injection to groups of unanaesthetized rabbits at doses of 100-200 micrograms/kg and by intravenous infusion at doses of 10-20 micrograms/kg/min. In other experiments, SUL was chronically administered p.o. to normal rabbits and to rabbits receiving Kritchevsky's atherogenic diet; the daily dose of the drug was about 16 mg/kg. Cerebral blood flow and its compartmental distribution were determined in unanaesthetized animals by the intracarotid 133Xe clearance method. The data demonstrate that the atherogenic diet brings about a significant impairment of CBF; SUL is inactive in normal rabbits, while in the atherosclerotic rabbits it induces a pronounced increase in cerebral blood flow in the grey matter and an enhancement of the corresponding circulatory compartment. These changes are less evident in the white matter.

Anesthesia↗
PubMed1985

Preliminary evaluation of myocardial toxicity of 4'-deoxydoxorubicin: experimental and clinical results.

4'-deoxydoxorubicin (4'-deoxy-DXR), a new doxorubicin (DXR) analogue with interesting antineoplastic activity, was tested for its cardiotoxicity in guinea pigs and humans. In experiments on isolated guinea pig heart, which is considered a highly predictive model of acute anthracycline cardiotoxicity in humans, 4'-deoxy-DXR was found to be significantly less cardiotoxic than DXR. This effect was correlated with a lower degree of inhibition of the fast-exchanging calcium compartment and of the low affinity sarcolemmal calcium-binding sites. The preliminary study on 4'-deoxy-DXR in humans was conducted on 117 patients affected by advanced malignancies resistant to conventional chemotherapy. The drug was administered by bolus i.v. injection in doses ranging from 10 to 40 mg/m2 in the phase I study and in doses of 35 mg/m2 in the phase II study, which is still ongoing. Cardiologic evaluation consisted of recording of EKG, left ventricular systolic time intervals (STI), echocardiography and radionuclide ejection fraction. Preliminary data indicated a lower percentage of EKG abnormalities in comparison not only with DXR but also with other anthracycline analogues. Analysis of STI recorded 1 h after different doses of 4'-deoxy-DXR failed to show the dose-dependent effect on left ventricular function which has been described for DXR, thus confirming the lower acute cardiotoxic effect. Functional parameters serially measured to evaluate chronic cardiotoxicity in 15 patients who received more than 200 mg/m2 were not significantly different from basal values.

Adult↗