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The study focused on the changes of microcirculation indices and components of the vascular tone of endothelial, neural, and myogenic nature in symmetrical skin sites of temples, forehead, auricles, scapulae, and groin during postnatal ontogeny. Initially, microcirculation indices in the symmetrical regions decreased to postnatal day 10, thereafter they surpassed the initial level at the age of 30 days. The endothelial, neural, and myogenic indices of vascular tone changed differently in the symmetrical left and right sites. On the right side, all indices increased by the postnatal day 21 ("redundancy" phase), and by postnatal day 30 surpassed the initial level by two times. On the left side, the redundancy phase manifested in the endothelial component on postnatal day 10, but to postnatal day 30 all three indices dropped below the initial level.

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Intravital microscopy and high-frequency ultrasonic system equipped with a microtransducer working at 38.5 MHz were employed to record blood velocity in arterioles and venules in the symmetrical fragments of the microvascular bed in frog tongue. The diameters of the vasculature ranged 75-200 µ. The record length was 2-5 min. The range of blood velocities was wider in the left arterioles than in the right ones, and inversely, it was greater in the right venules than in the left ones. The high-frequency and respiratory harmonics (0.2-1.5 Hz) dominated in the velocity spectrum of microvessels at each side, the greatest values being 64.6 and 72.3% for the left venules and the right arterioles, respectively. The low-frequency harmonics (0.009-0.02 Hz) were rare observed (7.6-15.4% examined vessels). They appeared in vessels with pronounced difference between the maximum and minimum velocities, in the cases with velocity variations looking like batches (bursts), etc. Correlation of velocities in arterioles and venules was positive at the left side (0.451) and negative at the right side (-0.574) of the tongue.

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Laser Doppler flowmetry showed that aspirin can induce blood flow reduction and transitory manifold increase or decrease in vascular tone in rat skin and kidneys. The dynamics is more illustrative when parameters of individual animals are evaluated and depends on the areas of blood flow recording. Deaths and reduction of narcotic sleep duration were noted in concomitant use of nembutal and aspirin.

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Laser Doppler flowmetry studies showed that blood flow in the microcirculation bed of paired buccal pouches in hamsters decreased under conditions of reduced systemic blood pressure and this decrease is more pronounced in the left pouch. The transition of the circulatory bed to the new state is step-wise in the left pouch and continuous in the right one.

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Using implanted camera we studied hamster buccal pouch microvessels under conditions of reduced blood pressure. The correlation (R=0.30-0.85) between the diameter and pressure was observed in 42% vessels. During progressive decrease in blood pressure, R for the majority of left venules was below zero, while left arterioles had equal probability of having R<0 and R>0. For right venules the positive and negative correlations were equally probable, while right arterioles were predominantly characterized by R>0. Heterogeneous reactions in microvessels of different diameter were revealed.

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Effects of exogenous nitrogen oxide (NO) on the time course of results of laser Doppler flowmetry (LDF) and biomicroscopy of the buccal sac capillaries were studied in a hamster pre-exposed to UV light. After NO treatment capillary vasodilatation was replaced by vasoconstriction in the focus of UV exposure. Parameters calculated by Dopplerograms indicate an increase of the vascular tone.

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Arteriolar and venular reactions and capillary blood flow in response to exogenous nitric oxide were studied on the hamster buccal sac capillaries. Heterogeneous reactions of capillaries were observed after exposure to NO; vasoconstriction and vasodilatation were observed equally often, the reactions of arterioles and venules being specific. The microcirculation index changed negligibly, the fluxmotion index increased due to increasing effects of active mechanisms, and the vascular tone decreased.

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Microvessels of rabbit left and right ear chamber and blood samples drawn from the internal ear vein in response to hemoconcentration were studied. The apparent viscosity of the outflowing blood in the left side was shown to be preserved with an increase of hemoconcentration. In the right one episode of increasing occurred. The invariance of the total area of perfused microvessels to increased hemoconcentration in the right side was fixed, whereas in left side it changed. The variation of regional resistance was analysed on the basis of our data according to Poiseuille's [correction of Puazeil] equation.

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Microvessels of rabbit ears chamber and blood samples drawn from the internal ear vein have been studied after blood substitution. It has been shown that the left microvessel bed responds to the hemodilution with 38% decrease of its length and 5.9% decrease of the mean diameter of its vessels, decrease apparent viscosity of outflowing blood, but RBC concentration per volume unity of blood (N) being preserved. The right one--with 7.8% increase of microvessel diameter, their length being preserved and 10% increase of the N.

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Microvessels of rabbit ears chamber and blood samples drawn from the internal ear vein after 30 min ischemia were studied. In the initial state the length of the left ear microvascular bed was 1.5 times higher, mean microvessel diameter 14.6% less, apparent viscosity of outflowing blood 16.8% less, RBC concentration per volume unity of blood 8% higher, RBC electrophoretic mobility 13.7% higher than those in the right one. It was shown that the left microvessel bed responds to the ischemia with the 13.2% increase of its length and 13.6% increase of the outflowing blood viscosity, the right one--with the 9.7% increase of microvessel diameter and 7.9% decrease of the viscosity.

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Microvessels of the rabbit ear chamber and blood samples drawn from the internal ear vein were studied after 30-min ischemia. Total microvascular bed area augmented by 16%, total microvascular bed length increased by 9% and mean microvascular diameter increased by 6.7%. One hour after the onset of ischemia it is only the diameter that remains augmented. In the control experimental series apparent viscosity of the blood flowing from the ischemic area did not correlate with the degree of vascularization, negative relation with vessel length (p = --0.461) and positive relation with the diameter (p = 0.799) being revealed. After ischemia only the viscosity-diameter relation remained significant (p = 0.466). The correlation matrix 10 X 10 which reflected the connection between other parameters characterizing specificity of blood supply regulation is given.

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