The behaviour by increasing the ventricular volume of several parameters and indices proposed for measuring the cardiac contractility has been determined in isolated guinea pig hearts beating under isometric conditions. Particularly, V max calculated on the total pressure has been compared with the Vmax calculated on the developed pressure. Whilst the later showed to be independent of preload changes, Vmax was calculated on the total pressure, decreased by changing the ventricular volume. Moreover, it showed itself to be independent of pre-load changes. An index proposed recently obtained from the plot (P, P'), as ratio between the positive portion of the area and the developed sistolic pressure wals also demonstrated.

Animals↗

PubMed1974

[Hemodynamic changes in the lower limbs induced with a nicotinic acid derivative (ES-902)].

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Adult↗

PubMed1974

[The computer assessment of cardiac contractility (author's transl)].

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Animals↗

PubMedDate not supplied

No-mimetic furoxans: arylsulphonylfuroxans and related compounds.

A new class of methylfuroxans and methylfurazans arylthio, arylsulphinyl and arylsulphonyl substituted, characterized by vasodilating and antiaggregatory properties, is described. Vasodilating activity, tested on rabbit aortic rings percontracted with 1 microM noradrenaline, is enhanced by N-oxidation of the furazan ring and is maximized by increase of the sulphur atom oxidation level. Compounds 4-methyl-3-(p-methoxyphenylsulphonyl) furoxan 6c, 3-phenyl-4-phenylsulphonylfuroxan 10, 4-phenyl-3-phenylsulphonylfuroxan 11 and 3,4-bis(phenyl-sulphonyl)furoxan 12 (EC50 values ranging between 0.055-1.07 microM), seem to be promising since they show the highest potency as well as maximal efficacy, causing complete reversal of noradrenaline induced contraction. The structure-activity relationship, observed in the platelet aggregation test, is substantially similar to that reported for the vasodilating activity, in line with the general profile of these drugs as putative NO-mimetic derivatives.

Animals↗

PubMedDate not supplied

Pharmacological activity of bamifylline on lung anaphylaxis: in vitro studies.

Bamifylline, a 7-8 disubstituted theophylline derivative, reduces in a dose dependent way (1 x 10(-5) M, 1 x 10(-4) M and 1 x 10(-3) M) the release of histamine, TXB2 (measured also as TXA2-like material) and SRS-A (as LTD4-like material) during the immunological challenge of actively sensitized guinea-pig lungs perfused in vitro. Theophylline was significantly less potent than bamifylline and particularly, at the higher concentrations used (1 x 10(-3) M), bamifylline was 2.7 times more potent than theophylline in reducing the immunological release of histamine and 1.6 and 1.5 times more potent in inhibiting the production of TXB2 and SRS-A, respectively. These data suggest that the ability of the two xanthine derivatives to control the immunological release of histamine represents an important point in understanding the mechanism of their anti-anaphylactic activity.

Anaphylaxis↗

PubMedDate not supplied

Cardiovascular effects induced by the injection of a new nonionic contrast medium (Iopamidol): experimental study in dogs.

The hemodynamic effects induced by the injection in the pulmonary artery of the new nonionic water soluble contrast medium Iopamidol were compared with those obtained by the injection of two other currently used contrast media (meglumine diatrizoate and sodium iothalamate). The experiments were carried out in nine mongrel dogs. Hemodynamic variables were continuously measured prior to, during, and for 8 minutes after injection of the contrast media. Injections of iopamidol produced significantly smaller decreases in aortic pressure (p less than 0.01), contractile indices (p less than 0.01), and peripheral resistances (p less than 0.01), and changes in heart rate and in cardiac output were less pronounced. At 3-4 minutes after injection, an increase in Vmaxd was observed with all three contrast media, but it was significantly lower after injecting Iopamidol. The role of hyperosmolality in causing cardiovascular changes is discussed. The less significant changes induced by Iopamidol appear to be the result of its lower osmolality, which is about a third that of meglumine diatrizoate or sodium iothalamate.

Animals↗

PubMedDate not supplied

Cardiovascular effects of nicardipine in anesthetized open-chest dogs in the absence and presence of beta-adrenergic receptor blockade: a comparison with nifedipine and verapamil.

Nicardipine, a new 1,4-dihydropyridine calcium-entry blocker, was assessed for cardiovascular effects against nifedipine and verapamil in anesthetized open-chest beagle dogs, in the absence and presence of beta-adrenoceptor blockade (propranolol 1 mg/kg i.v.). In control conditions, intravenous nicardipine and nifedipine (30 nmol/kg) produced decreases in blood pressure of similar magnitude without evidence of cardiodepression. An equihypotensive dose of verapamil (300 nmol/kg), by contrast, induced long-lasting negative chronotropic and inotropic effects, which, when combined with the effects of propranolol, were so marked as to cause the death of two of five dogs (atrioventricular block). Dihydropyridine derivatives at higher doses (100 nmol/kg) produced different responses: nifedipine depressed cardiac performance significantly more than nicardipine and, in the presence of beta-adrenergic blockade, caused the death of three of six dogs due to cardiovascular failure. In the nicardipine group, on the contrary, cardiac function was adequately preserved even in the presence of beta-blocker, and no animals died. The results of the present study confirm a previous in vitro observation: nicardipine is a calcium-entry blocker devoid of remarkable cardiodepressant effects and particularly selective for the vascular smooth muscle.

Adrenergic beta-Antagonists↗