Clonidine and vasomotion physiology.

It is known that clonidine exerts a hyperpolarizing action and alpha 2-adrenergic activity. The experimental work investigates the conditions under which each action of clonidine is developed on vascular smooth muscle. Two parameters were studied in vitro on bovine aortic media, Ca2+ uptake and vascular tone.

Evaluation of cardiac subacute toxicity of epirubicin, chlorambucil, cisplatin, methotrexate and a homo-aza-steroid ester with antitumor activity in rats using serum biochemical parameters.

Cardiac subacute toxicity induced by the antineoplastic drugs epirubicin (CAS 56390-09-1), chlorambucil (CAS 305-03-3), cisplatin (CAS 15663-27-1) and methotrexate (CAS 59-05-2) and the steroid alkylating agent 3 beta-hydroxy-13 alpha-amino-13,17-seco-5 alpha-androstan-17-oic-13, 17-lactam ¿p-[bis(2-chloroethyl)amino] phenyl¿ acetate was investigated in rats using serum biochemical parameters. Toxicology evaluation was performed in serum samples following the administration of dose regimens of the agents that were previously shown to be effective in suppressing malignant tumor growth or to prolong survival in tumor-bearing animals. Cardiac subacute toxicity was evaluated by measuring serum enzyme activity of creatine kinase, creatine kinase isoenzyme-MB, lactate dehydrogenase and aspartate aminotransferase.

Ultrastructural changes of the myocardial and striated muscle following a challenge of normobaric hyperoxia: the protective effects of alpha-tocopherol.

Normobaric hyperoxia has known deleterious effects on survival, presumably due to the generation of superoxide anion and hydrogen peroxide. To investigate the anatomical substrate of the effect of normobaric hyperoxia on the myocardial and striated muscles and the protective effect, if any, of alpha-tocopherol (vitamin E) on these tissues, we administered 95-99% O2 to adult male Wistar rats for 24, 48, 60 and 72 h. The animals were divided into four groups: 1) control I: six rats which breathed room air were used as controls for the ultrastructural studies; 2) control II: 10 rats which breathed 95-99% of O2 for up to 72 h were used as controls for arterial pressure, blood gases/pH, PvO2 and Hb measurements; 3) group A: hyperoxia: 24 rats divided into four subgroups according to the time of exposure to hyperoxia, A24, A48, A60, A72; and 4) group B: alpha-tocopherol/hyperoxia: 24 rats treated with alpha-tocopherol, 15 mg/kg/day, for 14 days before the beginning and throughout the period of hyperoxia, were divided into four subgroups (B24, B48, B60, B72) according to the time of exposure to hyperoxia.

Comparative study of SCE induction and cytostatic effects by homo-azasteroidal esters of N,N-bis(2-chloroethyl)aminobenzoic acid in human lymphocytes.

The effect of homo-azasteroidal esters of benzoic acid mustard isomers and the 4-methyl derivatives, which have steroidal lactams as a biological basis, on cytogenetic damage was studied. Twenty compounds were comparatively studied, on a molar basis, as regards their ability to induce sister-chromatid exchanges (SCEs) and cell division delays. A correlation between potency for SCE induction, effectiveness in cell division delay and previously established antitumor activity of these compounds was observed.

Felodipine and vasomotion physiology.

This study concerns the investigation of felodipine's influence on some parameters of vasomotion physiology. Felodipine is a new generation 1,4 dihydropyridine (1,4 DHP) Ca(2+)-entrance blocker with marked vascular selectivity. It was found that felodipine 1-10 microM presents a Ca2+ entrance-blocking activity when the bovine aortic smooth muscle is normal or stimulated by K+ 65.

Interactions between digitoxin and some antiarrhythmic drugs.

In the present study the pharmacokinetic interactions between digitoxin and the antiarrhythmic drugs amiodarone, mexiletine and propafenone have been examined. Experiments were performed on rabbits in which serum digitoxin concentration was used as indicator to detect drug interactions. The radioimmunoassay "Coat-A-Count" procedure of DPC was used for the quantitative measurement of digitoxin.

The influence of methionine-5-enkephalin on calcium uptake by the bovine aortic media.

The influence of methionine-5-enkephalin (M-5-E), an endogenous opioid receptor agonist, on calcium uptake by bovine aortic media was investigated in vitro. 45Ca was used and radioactivity was counted in a beta scintillation counter. M-5-E increases Ca2+ uptake by the preparation.

The influence of amikacin on digoxin uptake by certain rabbit tissues in vitro.

The influence of amikacin on digoxin uptake by various rabbit tissues was investigated in vitro. 125J-digoxin was used and radioactivity was counted in a gamma scintillation counter. Amikacin decreases digoxin uptake by the renal tissue and this action is probably due to a displacing effect.

The influence of piracetam on digoxin up-take by different rabbit tissues in vitro.

The action of increasing piracetam concentration on the digoxin up-take by various rabbit tissues was investigated in vitro. 125J-digoxin was used and radioactivity was counted in a gamma scintillation counter. Piracetam 100 micrograms/ml has a small increasing action on digoxin up-take by parenchymatous rabbit tissues.

Interaction of aminoglycoside antibiotics and calcium channel blockers at the neuromuscular junctions.

Aminoglycoside antibiotics (mmol.l-1) gentamicin (0.74), streptomycin (1.