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Biomedical subjects

A Popova

Publications and source records attributed to A Popova.

27 records · Page 2Linked to original sources
PubMed1976

On the neurogenic vasoconstriction of the resistive vessels in cutaneous vascular bed--rabbit ear.

A study was made of the effect of increased sympathetic activity during bilateral carotid occlusion (BCO), during haemorrhage and during i.v. injection of Tetramethylammonium jodatum (TMAI) on the resistive vessels in rabbit ears. The animal was under slight urethane anaesthesia, with spontaneous respiration after tracheotomy and vagotomy. The ear was perfused by roller pump with constant flow with tempered oxygenized Tyrode solution or with blood from a donor-animal. The increase in sympathetic activity during BCO, haemorrhage and injection of 100 mg/kg TMAI did not change the perfusion pressure in the perfused rabbit ear. The initial perfusion of the ear with blood increased the resistance of the ear, while perfusion with blood from donor-animal which had suffered considerable haemorrhage caused additional increase in the resistance by about 150 per cent. The effect of sympathetic constrictory influence of the resistive vessels is studied in view of the anatomic-functional specificities of the nerve supply of the ear and of the cutaneous vessels, in view of the passive dilatation of the resistive vessels, and of the thermoregulatory function of the ear. It is indicated that considerable hormonal vasoconstriction probably occurs in the rabbit ear during haemorrhage.

Animals↗
PubMed1976

Vascular effects upon experimental increase in the interstitial osmolarity.

Experimental increase in the interstitial osmolarity in the limb of a cat is caused by intraarterial infusion of hypertonic solutions. The limb was autoperfused with blood at a constant flow using a roller pump. Hypertonic Tyrode solutions with increased content of NaCl, glucose, l-ascorbic acid, with normal or increased KCl content, were infused together with the blood. The perfusion and arterial pressures were measured and the constrictory response upon local intraarterial injection of 0.2 mug 1-noradrenaline was determined. The intraarterial hypertonic infusion evoked a vasodilatatory response which was maintained irrespective of the reduced or preserved vascular contractility. The magnitude of the vasodilatation was determined by the hypertonicity of the solution and by the KCl content. Hyperosmolaric reduction of the vascular contractility was lacking in the case of solutions with increased KCl content or addition of l-ascorbic acid. The vasodilatation observed also when the contractility was not reduced is discussed in view of the participation of a passive vasodilatation caused by the dehydration of the vascular wall. The effect of the changes in the transmembrane Na+ and Ka+ concentrations on the reduction of the vascular contractility is also discussed.

Animals↗
PubMedDate not supplied

Effect of membrane fluidity on photoinhibition of isolated thylakoids membranes at room and low temperature.

The relationship between thylakoid membrane fluidity and the process of photoinhibition at room and low (4 degrees C) temperature was investigated. Two different membrane perturbing agents--cholesterol and benzylalcohol were applied to manipulate the fluidity of isolated pea thylakoids. The photochemical activity of photosystem I (PSI) and photosystem II (PSII), polarographically determined, were measured at high light intensity for different time of illumination at both temperatures. The exposure of cholesterol- and benzylalcohol-treated thylakoid membranes to high light intensities resulted in inhibition of both studied photochemical activities, being more pronounced for PSII compared to PSI. Time dependencies of inhibition of PSI and PSII electron transport rates for untreated and membranes with altered fluidity were determined at 20 degrees C and 4 degrees C. The effect is more pronounced for PSII activity during low-temperature photoinhibition. The data are discussed in terms of the determining role of physico-chemical properties of thylakoid membranes for the response of photosynthetic apparatus to light stress.

Benzyl Alcohol↗