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Recent discoveries in nonlinear optical properties of nanoparticle colloids make actual the challenge to lower the energy threshold of phase conjugation and move it into the domain of shorter pulse widths. A novel effect of the stimulated Rayleigh-Mie scattering (SRMS) in two-photon absorbing nanocolloids is considered as a promising answer to this challenge. We report the results of experimental and theoretical study of the two-photon-assisted SRMS in Ag and ZnO nanocolloids in the nanosecond-to-picosecond pulse width domain. For 12 ns 0.527 μm laser pulses, the four-wave mixing SRMS scheme provides lasing and amplification of backscattered anti-Stokes signal in Ag nanocolloids in toluene at the threshold 0.2 mJ and the spectral shifts up to 150 MHz. For 100 ps 0.532 μm pulses, we observed for the first time efficient (over 50% in signal-to-pump ratio of pulse energies) SRMS backscattering of the anti-Stokes signal in Ag nanocolloids in toluene and predominantly Stokes signal in ZnO nanocolloids in water, with the spectral shifts up to 0.25 cm -1 . We develop the first order-in-perturbation model of the four-wave mixing two-photon absorption-assisted SRMS process which shows that at nanosecond pulses, amplification is predominantly due to the thermal-induced coherent oscillations of polarization while the slow temperature wave acts also as a dynamic spatial grating which provides a self-induced optical cavity inside the interaction region. At a picosecond pulse width, according to our model, the spectral overlap between pump and signal pulses results in formation of only the dynamic spatial temperature grating, and we succeeded at recovering the linear growth of the spectral shift with the pump power near the threshold.

For a laboratory discharge initiated in a long air gap by a microsecond megavolt pulse, we simultaneously register wideband high-frequency microwave and hard-x-ray emissions and thoroughly analyze the temporal relationship of the emissions depending on the discharge evolution. The temporal structure of microwave radiation is found to consist of numerous short intense bursts with high-frequency components. We directly show that x-ray and microwave emissions can appear almost synchronously in the discharge but only when a complex net of countless plasma channels forms and spans the entire discharge gap. The channel formation is closely related to the intense development of multiple streamers.

The adrenergic contractile responses of smooth muscles in the vascular wall of guinea pig pulmonary arteries were studied during ovalbumin sensitization. Sensitization was followed by inhibition of contractile responses to an alpha-adrenoceptor agonist mesatone, prevented endothelium-derived relaxation, and potentiated the contractile response to isoproterenol. Administration of a beta-adrenoceptor agonist isoproterenol potentiated the increase in mechanical strain of smooth muscles in the pulmonary artery precontracted with high-potassium Krebs solution. Removal of the endothelium had no effect on the contractile response of smooth muscle segments from the pulmonary artery of intact and sensitized guinea pigs to b-adrenergic influences. The contractile responses of smooth muscles of the pulmonary artery are associated with activity of the cAMP-dependent signal system and play a role in the pathogenesis of ventilation-perfusion disturbances during atopic inflammation.

Experiments on isolated rat liver perfused with Ringer-Krebs bicarbonate buffer showed that stimulation of delta-opiate receptors in this organ increases bile flow rate and taurocholate secretion. Stimulation of micro-opiate receptors decelerated bile production and inhibited taurocholate secretion. Acceleration of bile production and stimulation of taurocholate secretion under the influence of dalargin is probably related to its interaction with delta-opiate receptors in the liver.

Exposure to X-rays causes pronounced morphofunctional changes in basal cells and modulates linear cellularity in the epidermal basal layer in guinea pigs. Radiosensitivity of skin basal cells of different location is different: the most pronounced morphofunctional changes were observed in the skin of the head (cheek) and abdomen.

The effect of Na(+),K(+),2Cl(-) cotransport inhibitor bumetanide on action potentials and contractions of smooth muscle cells in the ureter of guinea pigs evoked by electrical stimulation was studied by the method of double sucrose bridge. Bumetanide (10-100 microM) dose-dependently suppressed action potential and contractions of smooth muscle cells induced by 1-10 microM histamine, 10 microM mesatone, 5 mM tetraethylammonium, and 100 microM sodium nitroprusside. Our findings suggest that test substances modulate Na(+),K(+),2Cl(-) cotransport in smooth muscle cells.

The effect of nibentan (2.5 and 25 muM) on extrasystolic and post-extrasystolic contraction of isolated and perfused papillary muscle was studied. The muscle contracted in an isometric regimen at a rate of external electrical stimulation of 0.5 Hz in a temperature-stabilized chamber (36.0+0.5 degrees C). The extrasystolic contraction was induced with an extra electrical pulse applied 0.25 sec after the regular stimulus. Nibentan decreased the amplitude of extrasystolic contraction in a dose-dependent manner. At the same time, the effect of nibentan on extrasystolic contraction practically did not depend on its concentration. It is concluded that nibentan produces a dose-dependent effect on excitability of rat ventricular myocardium, and in parallel improves calcium-accumulating capacity of the sarcoplasmic reticulum in cardiomyocytes.

Muscle tension recording was used to study adrenergic contractile reactions of pulmonary artery smooth muscles in rabbits. Stimulation of alpha-adrenoceptors induced contraction of pulmonary artery smooth muscle cells. Endothelium partially inhibited the contractile effect of alpha-adrenoceptor agonists. Activation of smooth muscle beta-adrenoceptors in pulmonary arteries produced a dual dose-dependent effect (relaxation at agonist concentrations of 10 nM-1 muM and contraction at concentrations above 10 muM). The contractile effect of beta-adrenoceptor activation in smooth muscle cells is a specific feature of pulmonary arteries probably related to peculiarities of cAMP-signaling in these cells.

Function of sarcoplasmic reticulum was studied in rat papillary muscles treated with amiodarone. An extra stimulus (0.5 Hz) was delivered to the muscle 0.225 sec after application of a regular stimulus. Postextrasystolic potentiation was evaluated in control myocardial samples and samples treated with amiodarone. The preparation significantly increased all the parameters of postextrasystolic contraction. It was concluded that amiodarone potentiates the ability of sarcoplasmic reticulum to accumulate Ca2+ ions.

Double sucrose gap experiments were carried out to study the effect of phosphodiesterase inhibitors and penetrating analogs of cyclic nucleotides on action potential and contraction of guinea pig ureteral smooth muscle cells. 3-Isobutyl-1-methylxanthine (10 microM) and dibutyryl-cAMP (20 microM) shortened the plateau of action potential and inhibited contraction of smooth muscle cells by increasing potassium permeability of their membrane. Vinpocetine (1 microM) and dibutyryl-cAMP (100 microM) strengthened contraction of smooth muscle cells and shortened action potentials by decreasing sodium permeability of their membrane.

Histaminergic contractile reactions of smooth muscles in rabbit lobar pulmonary arteries were studied using in vitro mechanographic technique. Histamine via activation of H-receptors induced a dose-dependent constriction of smooth muscle segments, while endothelium inhibited histamine-induced contractile reactions. Histamine increased sensitivity of smooth muscle cells in pulmonary artery to sodium nitroprusside.

Presentation of visual and acoustic stimuli at a rate of 2-30 Hz modulated variability of the heart rhythm in volunteers. Potentation of vagal influences and a decrease in the contribution of ergotropic systems to the regulation of the heart rate were noted after 10 sessions of audiovisual stimulation. These changes were accompanied by a pronounced decrease of individual and reactive anxiety.

Cholinergic contractile reactions of smooth muscles in rabbit pulmonary arteries were studied by mechanography. The muscarinic receptor agonist pilocarpine induced biphasic relaxation of mesatone- or potassium-precontracted segments from lobar pulmonary arteries with intact endothelium. The low-threshold endothelium-dependent component of pilocarpine-induced relaxation was suppressed by denudation or nitric oxide synthase blocker L-NAME.

Double sucrose gap experiments revealed differences in the effect of nitroglycerin and sodium nitroprusside on action potential and contraction of ureteral smooth muscle cells. Unlike sodium nitroprusside, nitroglycerin inhibited voltage-dependent Ca(2+) membrane permeability. It was concluded that cGMP-independent mechanisms of the effects of nitro derivative reflect the peculiarities of excitation-contraction coupling in smooth muscles.