Biomedical subjects

O Petkov

Publications and source records attributed to O Petkov.

21 records · Page 2Linked to original sources

PubMedDate not supplied

Changes in ECG, plasma and myocardial lipids in experimental myocardial hypertrophy in rats.

ECG, systolic blood pressure (BP), the ratio (R) of grams of myocardial mass/100 g of body mass, total lipids, cholesterol, triglycerides and phospholipids in blood plasma and the left ventricular myocardium, as well as the plasma free fatty acids, were investigated in 58 male Wistar rats 3, 30 and 180 days after operation, in a model of myocardial hypertrophy (MH) induced by experimental coarctation hypertension, after the method of Selye. An attempt was made to correlate some functional and metabolic indices which characterize the development of this type of MH. On a background of progressively rising BP and parallel increasing R, ECG changes were recorded. They were typical of the respective stage of arterial hypertension and MH and expressed mostly in a shifting of the electrical axis of the heart to the left and in essential repolarization disturbances. The most significant changes in the studied lipid fractions were found 30 days after the induction of hypertension. The pathological changes manifested on the 180th day are discussed in relation to age, the stage of hypertension and especially in relation to the developing hypoxic and ischaemic myocardial damage.

Animals↗

PubMedDate not supplied

Effects of 4-(4-bromophenyl)-2-methyl-1,2,3,4-tetrahydroisoquinoline hydrochloride on acute gastric lesions, acid secretion in rats and on some hemodynamic parameters in cats.

The effectiveness of 4-(4-bromophenyl)-2-methyl-1,2,3,4-tetrahydroisoquinoline hydrochloride (AN12) on acute ulcer models and gastric acid secretion in rats was compared with the action of the histamine H2-receptor antagonist roxatidine (R). AN12 or R given orally, produced significant, dose-dependent decreases in stress- and indomethacin-induced ulcers. The ED50 value of AN12 and R were 0.40 (0.27-0.60) and 13.27 (9.13-19.29) mg/kg, respectively, for stress ulcers and 0.68 (0.17-2.61) and 25 mg/kg, respectively, for indomethacin ulcers. The length and number of ethanol-provoked gastric damages were significantly reduced by R (50 and 100 mg/kg p.o.) but not by AN12 (0.5-2 mg/kg p.o.). In pylorus-ligated rats, AN12 (2 mg/kg p.o.) and R (50 and 100 mg/kg p.o.) significantly inhibited basal gastric acid secretion, increased pH and decreased acidity. The influence of AN12 (2 mg/kg) on the volume of stomach juice was close to that of R (100 mg/kg), AN12 (0.1-1.0 mg/kg i.v.) did not significantly affect the hemodynamics of anesthesized cats. It is suggested that the influence of some CNS amine neurotransmitters may be included in part, in the effects of AN12.

Acute Disease↗

PubMedDate not supplied

Involvement of Ca2+ and alpha 1-adrenoceptors in endothelin-1 effects on the tone and electrically evoked contractions of rabbit ear central artery.

Endothelin-1 (ET-1) is a neuropeptide strongly involved in the functions of the cardiovascular system. The aim of the present study was to reveal the role of alpha1-adrenoceptors and of Ca2+ in the effects of ET-1 on blood vessels. Preparations isolated from the proximal part of ear central arteries (REA) of male Chinchilla rabbits were used. A 30-40 mm long segment, cannulated at both ends, was fixed in an organ bath with Krebs-Henseleit solutions aerated with 95% O2 and 5% CO2. The preparations were perfused at a rate of 3.0 ml/min maintaining the arterial pressure in the range of 40-60 HPa and were allowed a 120-min adaptation at 37.5 degree C. Contractions were induced by low-frequency electrical stimulation (ES) and the effects of ET-1 (applied intralumenally or extralumenally) on the arterial tone and on the Es-evoked contractions were studied. Extralumenal ET-1 (1 x 10(-12)M-1 x 10(-9)M) did not change the tone and ES evoked contractions of REA. In concentrations of 1 x 10(-8)M-1 x 10(-7)M ET-1 slightly increased arterial tone and moderately potentiated ES contractions. ET-1, in concentrations higher than 1 x 10(-7)M, sharply, strongly and long-lastingly increased the smooth muscle tone and slightly enhanced the ES contractions. A 100 microM bolus injection with ET-1 (1 x 10(-9)M-1 x 10(-8)M) resulted in potentiation of the ES contractions and the arterial tone was not markedly affected. 100 microM of 1 x 10(-7)M ET-1 increased more than 2-fold the tone of the segments and moderately reduced the ES-evoked contractions. A 30-min perfusion with ET-1 (1 x 10(-12)M-1 x 10(-9)M) strongly increased the arterial tone and completely abolished the ES contractions. Perfusion with 1 x 10(-8)M ET-1 resulted in a 3-fold increase of the tone of the isolated segments. A 30-min perfusion with 1 x 10(-6)M prazosin (PRZ) did not affect the arterial tone and prevented the ES-evoked contractions. PRZ markedly reduced the contractile effects of 1 x 10(-12)M-1 x 10(-9)M ET-1 and the effect of 1 x 10(-8)M ET-1 on REA tone was even enhanced by PRZ. Under the same conditions 1 x 10(-6)M flunarizine (FLU) inhibited the ES-induced contractions of the isolated preparations and decreased their tone. FLU reduced the contractile effects of ET-1 (1 x 10(-12)M-1 x 10(-8)M). Applied extralumentally 1 x 10(-6)M FLU also decreased EG-1 effects on REA. The results obtained strongly support the assumption that alpha1-receptors and Ca2+ are involved in ET-1 contractile effects on blood vessels smooth muscles.

Adrenergic alpha-Antagonists↗