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Biomedical subjects

V P Nikol'skiĭ

Publications and source records attributed to V P Nikol'skiĭ.

9 recordsLinked to original sources
PubMed1991

[The decisive role of the endothelium in stabilizing pressure losses during changes in the blood flow in small arteries].

Previously we established that the pressure drop along arteries remained nearly constant during the many-fold increase of blood flow rate. In anesthetized rats, functional damage of saphenous artery endothelium eliminates this local regulation of its resistance to flow. Hence, it is determined by the sensitivity of the endothelium to the shear stress. The sensitivity threshold has been estimated to be about 50-70 dyn/sm2. This is considerable more than the values characteristic of the cultured endotheliocytes. Possible reasons of this discrepancy under in vivo and in vitro conditions are discussed.

Animals↗
PubMed1991

[The effect of the stabilization of a drop in pressure in the arteries during changes in the rate of blood flow].

The saphenous artery was joined with the femoral vein in rats. The pressure drop was measured between the aortic arch and the distal end of the saphenous artery. The stabilization of the pressure losses during the increase of blood flow rate occurs and is determined by dilation mainly of the saphenous artery, the degree of this dilation being such that the pressure drop within the wide range of blood flow rate remain constant.

Animals↗
PubMed1990

[The diagnosis of renal artery stenosis by the data from ultrasonic study methods].

The purpose of the present investigation was to elaborate diagnostic criteria for stenosing of renal arteries according to ultrasonic dopplerography. The investigation included 35 patients suffering from vasorenal hypertension with stenoses of the renal arteries documented by angiography and 63 patients with stage II essential hypertension, who made up the control group. Ultrasonic scanning of the kidneys and dopplerography of the renal arteries were performed with the use of the Acuson-128 ultrasonic system fitted out with a sector transducer operating at a frequency of 3.5 MHz. The authors have devised a method of an ultrasonic study of the renal arteries by means of the posterolateral access. Established criteria for diagnosing stenosis of the renal artery. Among these are a decline of the pulsation index, the resistive index, and the systolic-diastolic velocity ratio as compared to the contralateral artery and nonstenosed renal arteries in the control group patients.

Adolescent↗
PubMed1987

[Stabilization of pressure drop in the feeder arteries of rats as affected by an increase in blood flow].

The dependence of the pressure drop (PD) along conducting vessels between the aorta and the distal end of a. saphena on the blood flow in the artery has been studied in rats. The PD was shown to react to rapid blood flow increase from 0.6 to 1.2 ml/min, with a drastic upstroke followed by a gradual decrease to the initial value within 20 s. When the blood flow was returned to the initial level the PD was recovered during 40 s. A rapid flow increase from 0.1 to 1.0 ml/min in 3 s was accompanied by proportional changes in PD. However, a slow blood flow increase from 0.1 to 1.5 ml/min in 600 s did not induce any marked changes in PD in the range of the blood flow from 0.5 to 1.5 ml/min. The observed stabilization of PD may be attributed to the property of conducting arteries to increase their internal diameter in response to blood flow increase.

Animals↗
PubMed1987

[Method of studying the reactions of single vessels in situ].

A new method of continuous measurement of vascular resistance has been proposed for studying the reactivity of single blood vessels. According to the method, blood flows through the artery, then through a rigid tube, serving as a reference resistance, and a flow control system and then returns back to the animal. The parameter of interest is pressure drop along the artery to reference resistance ratio. The method permits the study of practically intact vessels with diameters to 0.3 mm. Changes in blood viscosity have but a slight effect on the results of the measurement.

Animals↗