Biomedical subjects
Publications and source records attributed to V K Khugaeva.
The lymphatic microvessels of the rat mesentery do not contract rhythmically. Adrenaline and naloxone modulate the lymph-activating effect of opioid peptides (leu-enkephalin and dalargin).
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The cortical blood flow of the rat brain was decreased at 44% by the bilateral occlusion of common carotid artery. The intraperitoneal injection of the leu-enkephalin before and after ischemia restored the blood flow and increased the volume of the lymph in ductus thoracicus. Cerebrovascular action of leu-enkephalin was connected with its lymphostimulating activity and vasodilation.
The casein inhibitor of gastric secretion, when applied to the mesentery of anesthetized rat at doses 0.01-10.0 micrograms in 0.1 ml activated the lymph flow due to enhanced contraction of lymphatic microvascular wall and valves. Moreover, casein inhibitor administrated intraintestinally at doses 5 mg in 0.5 ml on rat keep its lymphotropic activity.
The contractile activity of the wall and valve of lymphatic microvessels (LM) of the rat mesentery were studied biomicroscopically by optic photometry. Opioid peptides-Leu-enkephalin and dalargin-stimulated LM. Preliminary application of naloxone on the LM prevented the appearance of the LM contractions following the Leu-enkephalin-application. Naloxone did not inhibit contractions of LM previously activated by Leu-enkephalin. It is supposed that opioid mechanisms are involved in the regulation of the LM contractile activity.
The inclusion of amino acids (tyrosine, arginine) into the end part of the peptide chain permits to produce new analogues stimulating the lymph microvessels of the rat mesentery and increasing the blood microvessels permeability.
Dalargin (a synthetic analog of leu-enkephalin), when applied to the microvessel surface or administered intramuscularly at doses 0.004-40.0 micrograms/kg increased the permeability of the rat mesenteric microvascular wall and activated the lymph flow due to enhanced contraction of lymphatic microvascular wall and valves. Moreover, Dalargin evoked leukocyte migration from venules and activated the intestinal muscular contractions.
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The dynamics of the capillary hematocrit in 4-5-, 7- and 11-week rats involved its reduction with ageing from 0.17 l/l in 4-5-week rats to 0.10 l/l in 7- and 11-week ones in spite of considerable variability in each animal group. The reduction of the hematocrit seems to be due to the growth of capillary net in mesentery.
Intravital studies of microcirculation and packed-cell volume in microvessels of rat mesentery demonstrated changes in the direction of the flow and packed-cell volume in the course of 17 minutes' ischemia caused by the occlusion of the afferent arteriole. Deficient inflow to the ischemized region is at first compensated for by the inflow from other microvessels via major anastomoses and later by retrograde flow through the peripheral branches of the occluded arteriole. The development of generalized microcirculatory disorders is preceded by capillary retrograde flow containing venular blood.
The erythrocyte redistribution in the rat mesentery microvessels and the development of postischemic microcirculatory disturbances were influenced by the thrombosis in narrow parts of arterioles and the increase in leukocyte adhesion to venule walls obstructing the blood outflow. The presence of branches and anastomoses in microvascular bed had a pronounced effect on reperfusion disturbances.
Short-term ischemia on the microvascular level in the rat intestine mesentery was induced by occlusion of the a. mesenterica superior or regional supplying arteriole for 1 or 10 min. No substantial disturbances of blood flow velocity and hematocrit occurred in microvessels after 1 min occlusion, whereas the blood flow cessation for 10 min was followed by a decrease of flow velocity in microvessels under study and development of thrombosis at the site of arteriole occlusion.
Experiments were made on rabbit fed an atherogenic diet (0.5 g/kg cholesterol) singly for 15 and 24 h and repeatedly for 3, 9 and 30 days. At early stages of lipid metabolism distress the interrelationship was established between blood rheological disorders and microcirculatory abnormalities. The dependence of the initial reaction of some rheological characteristics on their initial level was marked.
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The hematocrit index in the microvessels of the rat mesentery was studied in vivo before and after intravenous injection of polyglucin. It was maximal in arterio-venular anastomoses (44%) and minimal (11%) in the capillaries. Polyglucin reduced the hematocrit value in all the microvessels and to a greater degree in the arterio-venular anastomoses and capillaries.
It has been found that neuropeptide leienkephalin and tyrosine occupying an N-end position in the peptide chain of leienkephalin are activators of the contractile activity of lymphatic microvessels of the mesentery. It is being attempted to obtain an even more active leienkephalin analogue by increasing the tyrosine content in its peptide chain.
The effect of bradykinin on microcirculation was studied in vivo on the rat mesentery. Bradykinin (0.01--10 micrograms) caused three types of reactions of arterioles and venules (constriction, dilatation, no changes in the diameter) in relation to the dose used. Preliminary application of noradrenaline changed the sensitivity of microvessels to bradykinin towards the increased frequency of dilatation. The increased permeability by red cells in postcapillaries and in venules arose in the areas of the greatest stretch (sites of confluences and ridges of vessels wavy in outline) and was accompanied by deformation and shortening of venules. It was disclosed that bradykinin exerted a pronounced pain effect that promoted awakening of the animals from anesthesia.
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